2
Monograph
Groundwater Depletion and its Socio-economic and Ecological Consequences in Sabarmati River Basin
M. Dinesh Kumar, Om Prakash Singh and Katar Singh
Supported By Sir Ratan Tata Trust
India Natural Economics and Management Foundation
i
Monograph 2
Groundwater Depletion and its Socio-economic and Ecological Consequences in Sabarmati River Basin
M. Dinesh Kumar, Om Prakash Singh and Katar Singh
Supported by Sir Ratan Tata Trust, Mumbai
India Natural Resource Economics and Management Foundation, Anand Tower – B Ground Floor, Param Krishna Complex Anand, Gujarat, India Phone: 91-2692-62074, Email:
[email protected]
ii
CONTENT LIST OF TABLES ........................................................................................................................................................ IV LIST OF FIGURES ...................................................................................................................................................... IV ABBREVIATIONS .........................................................................................................................................................V ACKNOWLEDGEMENT ........................................................................................................................................... VI PREFACE ................................................................................................................................................................... VII ABSTRACT .................................................................................................................................................................... 1 1.0
INTRODUCTION AND BACKGROUND.......................................................................................................... 2
2.0
A CRITICAL REVIEW OF THE EXISTING METHODOLOGY TO ASSESS GROUNDWATER DEVELOPMENT .................................................................................................................................................. 3
3.0
ASSESSMENT OF GROUNDWATER OVER-EXPLOITATION .................................................................. 4
3.1 3.2
CONCEPTUAL ISSUES IN DEFINING OVER-EXPLOITATION ................................................................ 5 DEFINITION AND ASSESSMENT OF GROUNDWATER OVER-EXPLOITATION ............................... 6
4.0
GROUNDWATER OVER-DEVELOPMENT IN SABARMATI BASIN ........................................................ 8
4.1 CHARACTERISTICS OF AQUIFERS IN SABARMATI BASIN ................................................................... 8 4.2 DIMENSIONS OF GROUNDWATER OVER-DEVELOPMENT IN SABARMATI BASIN ..................... 10 4.2.1 HYDROLOGICAL ASPECTS ........................................................................................................................... 10 4.2.2 Hydro-dynamics ............................................................................................................................................................ 12
Trends in Piezometric Levels in Sabarmati Basin Area ............................................................................. 13 Water Level Trends in Open Wells in Sabarmati Basin Area .................................................................... 14 4.2.3 Economics of Groundwater Over-exploitation ........................................................................................................... 16 4.2.4 Social Aspects ................................................................................................................................................................ 19 4.2.5 Ethics of Water Use....................................................................................................................................................... 19 4.2.6 Ecological Consequences .............................................................................................................................................. 21 [a] Land degradation .............................................................................................................................................................. 21
Waterlogging and Salinity ........................................................................................................................... 21 Breaking of Soil Structure, Soil Retention Capacity and Loss of Organic Matter and Nutrients ............ 23 Increase in Soil Salinity Resulting from Irrigation with high TDS Water ................................................ 23 [b] Changes in Feasibility of Growing Agricultural Crops ................................................................................................. 25
4.3 4.4
HOW AND WHY GROUNDWATER IN SABARMATI BASIN GETS OVER-EXPLOITED? ................ 25 THE LOGIC OF OVEREXPLOITATION OF GROUNDWATER .............................................................. 27
5.0
SOCIO-ECONOMIC AND ECOLOGICAL CONSEQUENCES OF GROUNDWATER OVEREXPLOITATION ................................................................................................................................................ 28
5.1
DECLINING WATER LEVELS AND EMERGENCE OF WATER MARKETS AND OTHER SOCIOECONOMIC INSTITUTIONS ........................................................................................................................... 28
5.2
IMPACTS OF GROUNDWATER DEGRADATION ON ACCESS EQUITY AND EFFICIENCY IN GROUNDWATER USE ...................................................................................................................................... 30 5.2.1 Impact on Equity ........................................................................................................................................................... 30 5.2.2 Impact on Efficiency of Water Use .............................................................................................................................. 32
5.3 5.4
INCREASED DEPENDENCE ON IRRIGATION AND FERTILISERS ...................................................... 33 HEALTH IMPACTS OF GROUNDWATER QUALITY DETERIORATION ............................................ 34
6.0
CONCLUSIONS AND POLICY IMPLICATIONS ......................................................................................... 36
REFERENCES ............................................................................................................................................................. 36
iii
LIST OF TABLES Table No.
Tittle
1
Taluka-wise Recharge and Abstraction and Stage of Groundwater Development in Sabarmati Basin………………………………………………………………. Economics of Tube-well Irrigation in the Alluvial Area of Sabarmati Basin……. TDS and Electrical Conductivity Values of Water Samples from Selected Observation Wells in Sabarmati Basin Area ………………………………….…..
2 3
Page No.
11 18 24
LIST OF FIGURES Figure No.
Tittle
Page No.
1 2 3 4 5 6 7 8 9 10
Geological Map of Sabarmati River Basin Showing Two Aquifer Systems…….. Water Level Fluctuations in the Observation Well in Bavela, Danta and Ingoli… Water Level Trends in Open Wells in Sabarkantha……………………………… Water Level Fluctuations in Open Wells in Ghatlodia, Ahmedabad ……………. Water Level Fluctuations in Open Wells in Kheda, 1995-2000 ……………….... Historical Changes in Time Spent on Irrigation ………………………………… Water Level Fluctuations in Sample Wells in Mahi Command ………………… Historical Changes in Fertiliser Application, Daskroi, Ahmedabad …………….. Growth in the Number of Wells in Sabarmati Basin Area ………………………. Competitive (open access) Equilibrium Level and Socially Optimal Level of Exploitation of Groundwater ……………………………………………………. Groundwater Price Vs Implicit Cost of Extraction in Ode and Jetpur Villages of Ahmedabad District……………………………………………………………… Historical Changes in Irrigation Rates, Daskroi, Ahmedabad …………………... Historical Changes in Irrigation for Different Crops, Kadi, Mehsana …………...
9 14 14 15 15 17 21 23 26
11 12 13
iv
27 31 33 34
ABBREVIATIONS AMC CGWB CSSRI DNA GOG GUIDE GW GWSSB HP M2 M3 MCM ORG ppm RNA TDS UNDP
Ahmedabad Municipal Corporation Central Ground Water Board Central Soil Salinity Research Institute Di-ribonucleic acid Government of Gujarat Gujarat Institute of Desert Ecology Ground Water Gujarat Water Supply and Sewerage Board Horse Power Square metre Cubic metre Million Cubic Metre Operation Research Group Parts per million Ribonucleic acid Total dissolved solids United Nations Development Programme
v
Acknowledgement First of all, we would like to place on record our sincere thanks to Sir Ratan Tata Trust, Mumbai for financially supporting this study. But for their generous grant, it would not have been possible for us to undertake this study. The authors are extremely thankful to the Central Ground Water Authority, West-Central Region, Ahmedabad for having provided to us the data on groundwater levels, which formed the basis for most of the analysis presented in the paper. The authors have also extensively used the data published in official documents of several agencies and are thankful to all those who have contributed to those reports. In this context, the report titled, Integrated Water Resource Development in Sabarmati Basin’ deserves a special mention. Analysis of water use, which formed the corner stone of the study, was mostly based on the primary data collected from the field. The authors express their sincere thanks and gratitude to the hundreds of farmers and other water users in Sabarmati basin, who were extremely cooperative and patient in responding to our long queries related to water use parameters at a time when the region was reeling under severe drought for the second consecutive year. The authors are highly thankful to Dr. Tushaar Shah, Principal Scientist, International Water Management Institute, and our collaborating partner in this research, for his valuable comments on an earlier draft of this paper. Last, but not the least, the authors are highly thankful to Mr. Jose Scaria, who made all logistic arrangements for the fieldwork and also did part of the typing of the report.
Authors
vi
PREFACE In recent years, there have been several research endeavours focused on groundwater overexploitation in Gujarat. They have all contributed to the existing body of knowledge about the magnitude of water problems. A major limitation of many of those studies was their failure to take into account social, economic, ecological and ethical considerations and the complex nature of the physical or hydrological system in analysing over-exploitation problems. Also, there was very little analysis of the ecological consequences of groundwater degradation attempted in those studies. The ecological and environmental costs associated with groundwater degradation can often be too high to be over-looked, especially if we have to justify the potentially large investments required for management interventions to address the problems. In Sabarmati basin, nearly 63 per cent of the water required to the meet the needs of various users comes from groundwater; almost 75 per cent of the gross irrigated area in the basin is accounted for by groundwater; and nearly 80 per cent of the total water used for irrigation is extracted from wells. Groundwater is also the main source of water for rural and urban drinking purposes. The basin has a total of 282.2 billion cubic metres of static groundwater, which is mostly present in the deep confined aquifers of the alluvial plains in the basin, and 2.56 billion cubic metres of replenishable groundwater. This study is part of a major study aimed at analyzing the water management challenges that the basin is facing and exploring the range of options available for improving the management of scarce water resources in the basin. The findings of the study would help maintain the sustainability of water ecosystem and socio-economic growth. This paper is the second in the series of papers INREM Foundation is planning to bring out on different aspects of water management in Sabarmati river basin under the auspices of the project. The project is funded by Sir Ratan Tata Trust, Mumbai. This paper first critically reviews the existing methodology normally used to the assess over-development of groundwater in Gujarat and elsewhere in the country and discusses some of the conceptual issues involved in defining groundwater over-development. Then, it assesses the nature, extent and degree of groundwater problems in Sabarmati basin using some of the most commonly used definitions of ―groundwater over-development‖. Finally, it identifies and analyses certain causes of the problems and assesses their socio-ecological consequences. I hope the research scholars and managers engaged in river basin management will find the paper useful. Anand September 2001
Katar Singh Chairman
vii
Groundwater Depletion and its Socio-economic and Ecological Consequences in Sabarmati River Basin M. Dinesh Kumar, Om Prakash Singh and Katar Singh1 Abstract Groundwater accounts for nearly 75 per cent of the net irrigated area in the State. It quenches the thirst of nearly 40 million people living in the rural and urban areas of the State and contributes 25-30 billion rupees worth of agricultural outputs to the State’s economy every year. In Sabarmati Basin, nearly 63 per cent of the water required to the meet the needs various users comes from groundwater; and nearly 80 per cent of the total water diverted for irrigation is extracted from wells. Groundwater is also the main source of drinking water for rural and urban areas in the State. The basin has a total of 282.2 billion cubic metres of static groundwater, which is mostly present in the deep confined aquifers of the alluvial plains in the basin and 2.56 billion cubic metres of replenishable groundwater. Uncontrolled abstraction of groundwater in the basin is leading to several undesirable physical, socio-economic and ecological consequences. The basin is widely regarded as ―over-exploited‖. Analysing over-exploitation problems involves several social, economic, ecological and ethical considerations, apart from physical considerations of hydrologic balances. But such multi-disciplinary studies and analyses are lacking at present. There is need for conceptual clarity about the ways to diagnose, and analyse the degree and extent of the problem and its causes. This is because each of the causes has a separate implication for management actions that need to be initiated. Also there is need for deeper understanding of the ecological and socio-ecological consequences. This is important from the point of view of justifying the potentially large investments required for management interventions. This paper first critically reviews the existing methodology used to assess over-development of groundwater in Gujarat and elsewhere in the country. It then goes on to discuss some of the conceptual issues involved in defining groundwater over-development. The discussion covers the methodological issues involved in assessing recharge and abstraction, and the complex considerations involved in assessing the degree of ―groundwater over-development‖ or ―aquifer over-exploitation‖. The paper presents some of the most commonly used definitions of ―groundwater over-development‖. Based on these, the paper assesses the nature, extent and degree of groundwater problems in Sabarmati Basin. Finally, it identifies and analyses the causes of the problems and assesses their socio-economic and ecological consequences. The symptoms of an impending groundwater crisis in the basin include declining groundwater levels; poor economics of groundwater irrigation; unethical water use practices; drinking water scarcity in hard rock areas; and ecological problems such as land degradation. Over-exploitation of groundwater was found to have several socio-economic and ecological consequences such as access inequity in groundwater use for irrigation in favour of the rich and large farmers due to the presence of water markets; increased dependence of farmers on irrigation water; and threats to human biological and physiological health due to contamination of water with fluorides. The social, ecological and environmental costs associated with groundwater degradation in the basin are huge and should not be over-looked. As a result, the investment decisions for groundwater management projects to address these problems should be based on environmental, ecological, and social considerations. This would enable the policy makers to consider the positive environmental, ecological and social effects as the project benefits, which otherwise would continue to be lost sight of. Finally, groundwater management policies for ecologically fragile regions should be guided by the principles of sustainability, equity, ecology and environment rather than just economic criteria.
1
Senior Consultant, Research Officer, and Chairman respectively, India Natural Resources Economics and Management Foundation, Param Krishna Complex, Anand 388001.
1
Groundwater Depletion and its Socio-economic and Ecological Consequences in Sabarmati River Basin 1.0
INTRODUCTION AND BACKGROUND
Groundwater is a scarce and vital resource in Gujarat. It accounts for nearly 75 per cent of the net irrigated area in the State. Nearly 80 per cent of the rural population and half the urban population of the State are dependent on underground sources of water for drinking and domestic purposes. It quenches the thirst of nearly 40 million people living in the rural and urban areas of the State and contributes 25-30 billion rupees worth of agricultural outputs to the State’s economy every year. In the industrialised areas of Gujarat, which are also water-starved, groundwater provides one of the much-needed raw materials for manufacturing, which accounts for 35 per cent of the Net State Domestic Product. Groundwater is the only source of water for growing green fodder for the livestock in the three water-stressed regions of Central and North Gujarat, Kachchh and Saurashtra, which sustain the growth of the milk economy of rural Gujarat. The role of groundwater in the social advancement can never be over-emphasised, given the fact that today nearly 70% of the State’s population has access to safe water for drinking. It sustains irrigated agriculture and milk production in the rural Gujarat in years of drought, thereby acting as the ―drought buffer‖. In most of Kachchh, Saurashtra and North Gujarat, which receive scanty rainfall, and experience severe climatic conditions--high temperature, strong winds and aridity-- and frequent droughts, groundwater helps maintain the balance of the fragile ecosystems. In Sabarmati Basin, which has a human population of 92.8 million persons and animal population of 2.84 million, nearly 63 per cent of the water required to the meet various needs comes from groundwater. Almost 75 per cent of the gross irrigated area in the Basin is accounted for by groundwater. The diversion of water from underground sources for irrigation nearly 80 per cent of the total water diversion for agriculture. Groundwater is the main source for meeting rural and urban drinking water requirement. The basin has a total of 282.2 billion cubic metres of static groundwater, which is mostly present in the deep confined aquifers of the alluvial plains in the basin, and 2.56 billion cubic metres (as per official estimates of 1997) of replenishable groundwater. Uncontrolled exploitation of groundwater has led to several problems in the basin. They are manifested in four different ways: [i] secular decline in water levels in wells and tube wells; [ii] large seasonal drops in water levels in wells, especially in the hard rock areas; [iii] increasing salinity of groundwater in the coastal areas; and [iv] increasing incidence of high levels of fluorides and TDS in water in the alluvial areas. The major consequences are: [a] increase in pumping depths, reduction in tube well yields and enormous rise in the cost of pumping water; [b] widespread and acute scarcity of groundwater in summer months for irrigation in most parts of Saurashtra and Kachchh; [c] sharp reduction in good quality groundwater for irrigation and drinking in coastal areas; and [d] dental and skeletal fluorosis among people who are exposed to poor quality groundwater for drinking. Except seawater intrusion, the other three manifestations are apparent in the case of Sabarmati River basin. Often the official assessments of groundwater problems are based on certain norms used to estimate groundwater recharge (dynamic storage) and extraction. They do not capture the complex processes associated with the occurrence, storage and conveyance of groundwater. The methodology is rather simple and does not capture the complex concepts of over-exploitation. In 2
particular, as it does not take into account many critical variables such as long term and short term trends in water levels, long-term variations in well and aquifer yields, static storage of the aquifers being tapped, and their thickness that determine the degree of over-exploitation. Therefore, it is difficult to have a realistic assessment of the problem. So far, the public debates on groundwater problems in Gujarat have focused more on the ―manifestations‖ described above, and the consequences rather than the diagnosis of the problems themselves, their nature, degree and extent and the root causes thereof. Very little clarity exists on the ways to define the type of problems on the basis of the manifestations and the implications of each on groundwater availability and quality. Several misconceptions exist about the causes of the problems among the users, mainly farmers2. As a result, the discussions on the remedial measures have always centred on ―artificial recharge options‖. There is also very little understanding of the socio-ecological consequences of groundwater problems, while a lot of empirical evidence is available on the economic impacts such as rising cost of extraction of water, and emergence of markets. First of all, there is a need for conceptual clarity on the ways to diagnose, and analyse the nature and extent of the problems of ―groundwater over-development‖, and ―aquifer overexploitation, hydrostatic imbalance between seawater and freshwater‖; and their causes as each one has a distinct implication for management actions that need to be initiated to address the problems. Also there is a need for deeper understanding of the consequences --ecological and socio-ecological—which is important from the point of view of justifying the large investments required for management interventions. The purpose of this paper is to: [1] critically review the existing methodology to assess the nature and extent of over-development of groundwater; [2] demystify the complex considerations involved in assessing the degree of over-development so as to come out with a comprehensive framework for assessing over-development; [3] to provide a ―close to reality‖ assessment of the nature, extent and degree of groundwater problems in Sabarmati basin within this framework, and analyse their causes; and [4] assess the economic, social and ecological consequences of the problems. 2.0
A CRITICAL REVIEW OF THE EXISTING METHODOLOGY TO ASSESS GROUNDWATER DEVELOPMENT
In technical terms, groundwater development is assessed in terms of the ratio of the abstraction and the recharge. The official estimates of groundwater development are based on water level fluctuation approach. In this approach, the average annual recharge from precipitation is calculated by the following equation. Re = (As*Wf* Sy) + Dw Here ―Sy‖ is the specific yield of the aquifer, ―Wf‖ the average water level fluctuation, As the area of the aquifer, and ―Dw‖ the pumping during monsoon. The five-year average of the annual fluctuations in groundwater levels between pre- and post-monsoon time, multiplied by the specific yield values and the geographical area of the aquifer gives the total quantum of recharge. 2
One of them is associated with meteorological and hydrological phenomenon. Farmers, by and large, believe that the root-cause of groundwater level decline is the decline in annual rainfalls and the subsequent reduction in the natural recharge rate.
3
A major limitation of the official methodology is that it at the most works for simple aquifer units, and cannot capture the complex groundwater dynamics in multi-aquifer systems. Water level fluctuation is the net result of recharge, discharge, return flows, leakage from across the system etc. But, the water level fluctuation approach to estimating recharge --which often uses values of fluctuations in water levels within one or two layers of the aquifer system-- does not allow any discounting for the contribution from the existing storage from other layers of the aquifer, which could be very significant in the cases of deep alluvial aquifer systems with several layers. This can lead to an over-estimation of the recharge as contribution of the static storage of groundwater can lead to the inflation of the water level fluctuation during monsoon. Further, the official estimates provide aggregate figures of recharge and extraction. But, recharge is often confined to certain layers within the aquifer system—most commonly the upper shallow aquifer. So far as abstraction is concerned, there could be layers of the aquifer system, which are tapped but do not get natural replenishment either from rainfall or from leakage. As a result, different layers of the aquifer can undergo different degrees of exploitation, which will be reflected in the water level trends. However, the existing methodology for recharge and abstraction estimation treats the entire aquifer system as a single aquifer. Therefore, it fails to assess the degree of exploitation in different aquifers under consideration and may lead to a totally distorted picture of the stage of groundwater development in an area. Further, such a simplified methodology can lead to large errors in estimation. For instance, if the recharge calculations are based on the observations of water level fluctuations (pre- and post-monsoon) in the replenished aquifer, then it can lead to over-estimation of recharge benefits. The reason being that the calculation of gross recharge has to incorporate the abstraction during the monsoon period and though the abstraction could come from more than one layer, the entire amount is attributed to a single aquifer which is under consideration. The error in the estimation will depend on the extent of total abstraction during the monsoon period from the replenished aquifer. Often, water level data completely mismatch with the official data of recharge and abstraction. Water levels represent the net result of all the hydraulic processes taking place within an aquifer or aquifer system. A persistent negative evolution does not always mean that the abstraction is exceeding the recharge. Similarly, a steady water level situation may not always represent a desirable consequence for the entire groundwater system. The aquifer, which is being monitored, might receive the entire recharge from the top as well as leakage of the storage in the upper layer while several overlying aquifers might be contributing to the abstraction from the system. In sum, the methodologies used to assess groundwater development in Gujarat and other States in India are too simplistic to capture the complex hydrological considerations, and therefore are not realistic. 3.0
ASSESSMENT OF GROUNDWATER OVER-EXPLOITATION
In this section, we shall deal with the conceptual issues involved in defining groundwater over-development. The discussion will not touch upon the methodological issues involved in assessing groundwater recharge and extraction, but will identify the complex considerations involved in assessing the degree of ―groundwater over-development‖ or ―aquifer overexploitation‖. It will then present some of the most common definitions of ―groundwater overdevelopment‖ that use some of these considerations, so as to provide a comprehensive framework for assessing the same. 4
3.1
Conceptual Issues in Defining Over-exploitation
Terms as groundwater over-exploitation, over-draft, over-development, overuse and unsustainable use are commonly used in discussions on hydro-geology and groundwater resources since 1970’s (Custodio 2000). Such phenomena are predominantly applied in arid and semi-arid regions where large volumes of groundwater are abstracted to irrigate extensive areas, under situations when the natural recharge to aquifers is limited due to several reasons such as low rainfalls, un-favourable topographic and geo-hydrological environments. They are applied to aquifer conditions in other regions when exploitation leads to undesirable consequences. The concept of groundwater over-exploitation predominantly deals with negative aspects of groundwater development (ITGE 1991; Custodio 1992; Delgado 1992; Margat 1993; Custodio 2000). Such consequences may include: [i] large and continuous drops in groundwater levels over long time periods; [ii] large seasonal drops in water levels in wells and the drying up of wells in summer season; and [iii] increase in salinity of seawater; [iv] land subsidence; [v] enormous increase in cost of groundwater extraction; and [vi] reduction of groundwater dependent vegetation and springs and seepage. Custodio (2000), however, argues that though undesirable consequences appear when abstraction exceeds recharge, often there is no clear proof of the same being the cause of these undesirable consequences. This is true in case of Gujarat, where presently increasing incidence of fluoride in groundwater is a major problem whose causes are not clearly known. Fluoride content in groundwater can increase due to leaching of fluoride containing minerals present in geological formations with groundwater—a phenomenon not directly linked to over-extraction of groundwater. Similarly, fast seasonal drops in water levels are a serious problem in the Saurashtra districts that are underlain by hard rocks, threatening drinking water security. But some of these districts are still categorised as ―white‖ or ―grey‖ in terms of the stage of exploitation. Thus, the concept of ―groundwater over-development‖ or aquifer over-exploitation does not appear to be simple, merely linked to recharge and extraction balance, but is rather complex linked to various ―undesirable consequences‖ which are physical, social, economic, ecological, environmental, and ethical in nature. Therefore, an assessment of groundwater over-development involves complex considerations/concerns such as fundamental rights, basic survival needs, health, and economic, ecological and ethical issues and hence it is not possible to capture its essence with simple definitions. It is nevertheless important to mention here that there are fundamental differences in the way these ―undesirable consequences‖ are perceived by various scholars. For instance, according to Custodio (2000), it is predominantly the point of view of over-concerned conservationists, and people suffering from real or assumed damage, and not always of well-informed people. Collin and Margat (1992) have argued that this is an unconscious or incited over-reaction to a given situation, while Custodio and Llamas (1997) and Llamas (1992a) assert that this is the result of deeply entrenched ―hydromyths‖. Custodio (2000) further opines that the groundwater developers take the opposite position, which focus on ―beneficial use‖ and use the concepts of safe yield, or rational exploitation and the economics side of sustainable development to present their viewpoints. Such a logical framework for analysing the various viewpoints does not hold in several situations, including ours. First of all, the framework assumes that there are conservationists and those who are suffering from the damage, ―which is real or assumed‖, are different from the developers. This is not true. In many situations including one under consideration both are the same. It has been the rural communities, especially the farmers who are mostly engaged in groundwater development for irrigation and the consequences or the damage are also primarily 5
borne by them in terms of increased extraction costs and reduced well yields. Therefore, the argument that the concerns about ―over-exploitation‖ are an unconscious over-reaction to a given situation or are the result of deeply entrenched hydromyths itself is questionable. On the contrary, more systematic debates about groundwater ―over-development‖ mainly initiated by the researchers and scholars, including those from official agencies and NGOs were driven by concerns of maintaining sustainable water use in drinking water sector and agriculture. Official agencies mainly looked at farmers as the main culprits behind uncontrolled exploitation of groundwater, the researchers and scholars from development circles blamed the government policies and institutional framework. Several researchers from India have pointed to the need to integrate the concerns of intra-generational equity (Saleth 1994), social development, fundamental rights and economic efficiency in assessing the over-development of groundwater (Moench 1995). The official versions of over-development were primarily based on estimates of recharge and extraction. Therefore, they continued to treat areas with recharge exceeding the extraction as ―areas suitable for further exploitation‖ without worrying much about the consequent side effects. Those areas, where the average annual extraction figures exceeded the annual recharge figures, were treated as ―over-exploited areas‖ without giving due considerations to factors such as absence or presence of static groundwater storage. Though the groundwater scientists had emphasised the need for maintaining safe yields and sustainable levels of extraction to promote development with minimum negative ecological, economic and social consequences, the manifestations of over-development had appeared much earlier. Thus, such concepts have really not found any place in the practical and policy debates. Part of the reason is the realisation that ownership rights in groundwater are not well-defined, well development is highly decentralised under private initiatives and government does not have any control over the amount of groundwater that farmers could pump out. In sum, both the estimates based on field manifestations and official data (of recharge and extraction) are static and shortterm interpretations of the situation. They do not capture the complex physical characteristics and behaviour of aquifer systems, including large static groundwater storage, long-term effects, salinity and water quality issues, leakage from aquitards, the system recharge and discharge changes and the uncertainty. 3.2
Definition and Assessment of Groundwater Over-exploitation
Several researchers have tried to define groundwater over-exploitation and evolve criteria for assessing degrees of over-development, which integrate some of the concerns or considerations discussed early. The 1986 Regulations of the Public Water Domain of the Spanish Water Act (1985), define overexploitation by its effects: an aquifer is considered over-exploited or in the risk of exploitation, when the sustainability of existing uses is threatened as a consequence of abstraction being greater than one, or close to, the annual mean volume of renewable resources, or when they may produce a serious water quality deterioration problem (Custodio 2000). Young (1992) defined over-exploitation from an economic point of view, de-linking pumping rates from mean recharge values, as the non-optimal exploitation. Llamas (1992b) introduced the notion of strict over-exploitation –leaving room for definitions with broader scope as a groundwater abstraction producing effects whose final balance is negative for present and future generations, taking into account physical, chemical, economic, ecological and social aspects. The concept of sustainability used in the context of natural resource development by the Bruntland commission (Bruntland et al. 1987) based on the principle of inter-generational equity 6
is also used to define groundwater over-exploitation3 (Custodio 2000). However, GeorgescuReogen (1971) and Custodio (2000) have argued that the concept is too broad and cannot be applied to local specific situations, as it does not take into account the impossibility of complete recycling of matter. Another point of contention of Custodio is that if one strictly follows the principle of sustainable development, as proposed by the Commission, the non-renewable resources like the large and deep confined aquifers of arid regions yield no benefit to anyone. Thus, there is need for improving or extending the definition of sustainable development to include a variety of natural resources like aquifers. Finally, the way over-exploitation is perceived depends on points of views of different stake-holders involved such as farmers, water development administrators, ecologists, conservationists, mass media, naturists, and citizens and professionals such as engineers, scientists, economists, management specialists, environmentalists, lawyers, sociologists and politicians (Custodio 2000). For instance, one of the dominant perceptions of the farmers about the consequences of over-development --falling water levels, drying up of wells etc.--is that it happens due to frequent failure of monsoons and the long term sharp declines in annual rainfalls, sharply affecting the natural recharge rates. In fact, ―declining rainfalls‖ is a hydromyth existing among millions of farmers in the region4. Nevertheless, the farmers seem not to see well proliferation and increased groundwater draft as the major factors leading to over-development. On the contrary, droughts are perceived as a major cause of depletion. Farmers fail to recognise the fact that droughts are not a recent phenomenon. They continue to believe that the problems would cease to exist if good rainfall occurs continuously for a number of years. On the other hand, the official agencies claim with the support of their data of recharge and extraction that there are no reductions in the quantum of recharge over time5. However, here we do not rule out the chances of ―bias‖ in the estimates as they are often influenced by strong political interests. The direction of such a ―bias‖ could change depending on the kind of vested interest. If the ―vested interests‖ are for drilling more wells, the attempt will be to show lower rates of groundwater level drops and over-estimate the recharge figures. If the ―vested interest‖ is in large surface irrigation project in an area, which has considerable well irrigation, the attempt made would be to overplay the signs of over-development and unsustainable nature of present use of groundwater. Custodio has also talked about this ―bias‖ and manipulation as an important factor influencing the perception of over-exploitation The official perceptions of over-development are driven by ―aggregate views‖. They tend to compare taluka-level and district-level figures of recharge and extraction rates, and assess the magnitude of the problem on the basis of the same. In the process, they miss out several hidden phenomena such as excessive drawdowns in water levels due to large well-fields, groundwater pollution, and excessive rise in water levels causing water-logging, which are often localised.
3
4
5
The two major principles of sustainable development are: [a] the rate at which renewable natural resources are exploited should be less than the rate of regeneration; and [b] the waste flow into the natural environment should be kept less than its assimilative capacity. The arguments about long term declining trends in rainfall are also contested in the case of Gujarat (Bhatia 1992). However, the detailed analysis of the time series data on magnitude and pattern of rainfalls –including the number of rainy days, duration and intensity—are absent making it difficult to evaluate the impact of rainfall on groundwater recharge. In fact, the official data for Sabarmati Basin shows that the recharge had gone up during 1992-1997 as compared to the period 1987-91 (GOG 1992 and 1999).
7
In sum, defining and assessing of groundwater over-development are both difficult and complex and not amenable to simple formulations (Custodio 2000). According to Custodio, the reasons for this are as follows: Varying perceptions of people concerned: For instance, in Gujarat, often, ordinary people and the media refer to problems related to physical availability of groundwater, availability of economically accessible groundwater resources, groundwater quality problems, and seasonal drops in water levels as ―groundwater over-development problems‖. It is only in hydrology and geo-hydrology circles that such distinctions are ever made. The terms used to define over-exploitation vary with space and time; Persistent draw down trend is not a clear indicator: Groundwater behaviour being very complex in multi-aquifer systems—with several variables contributing to inflows and outflows-- groundwater level trends are not always clear indications of over-development and under-development. Difficulty in calculating aquifer recharge and integrating water quality with quantity: Difficulty in assessing long term trends in recharge rate that are very important; Importance of localised effects in the overall picture; Changing social perceptions and priorities; Improvements in water use technology; The need to consider the net socio-economic benefits; Complex nature of cost-benefit calculations; and Use of scarce, poor, and inappropriate data to define over-development. Therefore, in this paper, we attempt to make an actual appraisal of what is happening with the groundwater resources based on a detailed multi-disciplinary analysis of the situation and its evolution, taking into account the short and long-term goals. This will include analysing the degree of over-exploitation from the point of view of hydro-dynamics of the aquifer system, hydrology, ecology, economics, overall physical situation with regard to groundwater availability, equity, society, and ethical practices in water use. 4.0
GROUNDWATER OVER-DEVELOPMENT IN SABARMATI BASIN
4.1
Characteristics of Aquifers in Sabarmati Basin
The Sabarmati river originates in the metamorphic rocks of the Ajabgarh series of the Delhi system consisting mainly of Calc Schist, Calc gneiss and lime stones, which have a regional Northeast/ Southwest strike direction dipping towards the Northwest as well as the Southeast. The basin is underlain mainly by the rocks belonging to Pre-Cambrian age in its northern and eastern parts and recent alluvial deposits in the western and southern parts. The alluvial deposits underlie approximately two-thirds of the basin and are themselves underlain by rocks of Pre-Cambrian age. The maximum thickness of the sediments in the alluvial zone is 2600 meters. There are two distinct aquifer systems in Sabarmati basin area. First is a multi-aquifer system formed by alluvial sediments and the second an unconfined hard rock aquifer. Figure 1 provides the geological profile of Sabarmati river basin showing these two aquifer systems. The alluvial aquifer system in the basin extends over parts of Kheda, Ahmedabad and Gandhinagar district, a part of Kheralu taluka in Mehsana district, and parts of Himatnagar, Idar, Pantij and Dehgam in Sabarkantha district. The alluvial aquifer system is quite complex: it has a shallow unconfined aquifer as the upper layer, followed by alternate layers of clay and sand 8
9
forming semi-confining layers and aquifers. The thickness of the aquifer increases in the Northeast to Southwest direction. The shallow alluvial aquifer has a vertical extent of over 30 metres. According to a demarcation made for a UNDP study carried out in 1976, apart from the upper unconfined aquifer, there are 7 confined aquifers below. Though they are treated as confined aquifers, it should be believed that the aquitards are not completely impervious and that there is some amount of leakage taking place between layers governed by the hydraulic gradient. The alluvial aquifers have very high porosity and permeability and are good due to the high storage coefficient and transmissivity. The yield of the deep confined aquifers is as high as 20000 gallons per hour. The yield of the unconfined aquifer range from 8000-10000 gallons per hour in areas where the water table is still shallow. However, in the central parts of North Gujarat covering parts of Ahmedabad and Gandhinagar, the upper alluvial aquifer has gone dry. In the past, open wells tapping the upper unconfined aquifer used to be the main water abstraction structures in the basin. The open wells have now become dysfunctional in areas around Ahmedabad and Gandhinagar. In these areas, groundwater is now being abstracted through tube wells, which puncture the first and the second confined aquifers. Unconfined aquifers in the north-eastern parts of the basin are comprised mainly of igneous and metamorphic hard rocks with low yields indicated by transmissivity values ranging from 20-100 M2/day. This is also the case with Deccan Traps (basalt) occurring in the eastern parts of the basin under Sabarkantha district, and with igneous and metamorphic rocks in the North-North-western part of the basin under parts of Kheralu taluka of Mehsana district, and Danta taluka of Banaskantha district. Unconfined aquifers in the sedimentary Himatnagar Sandstone formations (mainly occurring around Himatnagar in Sabarkantha district) have medium yield characteristics with transmissivity values of around 250 M2/day. Open wells are still the most common groundwater extraction structures found in the area underlain by shallow hard rock aquifers, which encompass most parts of Sabarkantha district and some parts of Kheralu in Mehsana and Danta in Banaskantha. Of late, farmers have started drilling tube wells in this area to tap the water occurring in deep fractures. However, the yield of these bore wells is very poor. 4.2
Dimensions of Groundwater Over-development in Sabarmati basin
4.2.1 Hydrological Aspects The official estimates of groundwater recharge and extraction available for the talukas falling in Sabarmati basin’s drainage area available for the year 1992 and 1997 are analysed here to see the overall changes in groundwater balance during 1992-1997. However, in our analysis, we have considered the gross withdrawal figures provided in the report of a High Level Committee6 as the ―groundwater draft‖ for comparison against the utilisable recharge, which includes the return flows from irrigation. Whereas the Committee had treated the net withdrawal (after deducting the irrigation return flows from gross withdrawal) as the ―groundwater draft‖ for comparison with the utilisable recharge. Therefore, our estimates of the stage of groundwater development (expressed as the ratio of the gross draft and utilisable recharge) differ from that of the High Level Committee report. An important point with regard to estimating the stage of groundwater development, which needs a mention is that in 1997 estimates, 80 % of the gross recharge was treated as the utilisable 6
High level Committee on Estimation of Groundwater Resources and Irrigation Potential in Gujarat, Government of Gujarat, 1992 and 1999.
10
recharge, while in the 1991 estimates, it was 85 per cent. Further, the 1991 estimates classified talukas with extraction exceeding 85 per cent of the recharge as dark blocks, and talukas with extraction in the range of 65-85 per cent as grey blocks, whereas the 1997 estimates kept the limit for dark blocks at 90 per cent and grey blocks in the range of 70-90 per cent. We follow this norm for classification. Going by the 1991 official figures of utilisable recharge and gross draft, 15 out of the 28 blocks falling (fully and partly) are ―over-exploited7‖. Also, there were five ―dark‖ and four ―grey‖ talukas. But, according to the estimates based on their 1997 official figures, the number of ―over-exploited‖ talukas, and dark talukas are 11 and 3 respectively. But, the number of grey talukas had gone up to eight from five in 1991. At the aggregate level, the stage of groundwater development is 112 per cent according to our estimates using 1991 figures, while it is reduced to 102 per cent according to our estimates using the 1997 official figures. Table 1: Taluka-wise Recharge and Abstraction and Stage of Groundwater Development in Sabarmati Basin Name of Taluka
1. Dehgam 2. Dholka 3. Daskroi + A'bad city 4. Sanand 5. Danta 6. Gandhinagar 7. Anand 8. Borsad 9. Cambay 10. Kapadwanj 11. Matar 12. Mehmedabad 13. Nadiad 14. Petlad 15. Thasra 16. Kheralu 17. Vijapur 18. Kalol 19. Bayad 20. Bhiloda 21. Himatnagar 22. Idar 23. Khedabrahma 24. Malpur 25. Meghraj 26. Modasa 27. Prantij 28. Vijayanagar Total 7
Utilisable GW recharge 1991 1997 98.75 114.87 49.52 57.38 146.38 116.53 3.21 3.53 38.73 45.64 84.46 88.85 112.45 104.73 36.95 36.26 45.63 55.49 85.89 95.08 59.28 75.94 74.35 82.36 135.62 116.5 96.95 95.28 61.15 56.97 29.36 38.96 28.14 70.96 10.21 25.25 92.08 89.56 82.45 74.4 115.23 124.48 110.72 117.57 57.67 58.6 32.3 30.34 25.33 33.01 86.52 85.42 122.88 129.91 17.62 22.61 1939.84 2046.48
Total Groundwater draft 1991 1997 239.35 232.48 82.55 56.54 220.03 143.46 4.62 3.97 29.72 30.36 100.45 129.75 43.47 49.3 27.13 26.32 35.26 38.95 122.01 107.3 60.88 63.02 96.51 83.02 77.33 79.48 58.17 63.83 31.37 31.74 88.65 49.84 81.69 170.41 21.95 47.24 79.12 64.24 68.26 64.22 107.45 107.95 170.11 128.89 48.55 40.71 28.94 26.15 33.81 30.95 91.8 84.2 107.26 114.86 18.71 18.15 2175.15 2087.32
Stage of development % % 242 202 167 99 150 123 144 112 77 67 119 146 39 47 73 73 77 70 142 113 103 83 130 101 57 68 60 67 51 56 302 128 290 240 215 187 86 72 83 86 93 87 154 110 84 69 90 86 133 94 106 99 87 88 106 80 112 102
Talukas wherein the gross draft exceeds utilisable recharge or the stage of development is more than 100 per cent.
11
If we are to take the official figures of recharge and extraction as reliable, the above estimates mean that the degree and extent of over-exploitation has reduced during 1991-1997 in comparison to the previous 7 years from 1984-1991. This is indicated by the lower values of the ―stage of groundwater development‖ recorded for all the currently ―over-exploited‖ and ―dark talukas‖ in comparison to the previous years8, and the shifting of some of the talukas from ―overexploited to ―dark‖ category and from ―dark‖ to ―grey‖ category. But, the change in groundwater balance situation is not sufficient to reverse the negative water head evolutions caused by overdraft in those blocks that were earlier categorised as ―over-exploited‖ and still remain in the same category as per the revised estimates, though the rate of decline in water levels may have reduced. The reason being that the overall deficit in groundwater recharge-extraction budget had actually increased. In those talukas, which have shifted from the over-exploited category to ―dark‖ category, slight improvements in the hydrological balance situation is expected to have occurred resulting from the reduction in the overall deficit in groundwater recharge-extraction budget. 4.2.2 Hydro-dynamics In this section, we shall describe how the groundwater conditions in the study area have been changing over a period of time in terms of variations in pumping depths, fluctuations in static water levels in the phreatic aquifers, fluctuations in piezometric levels in the deeper aquifers, and the mechanisms used to pump groundwater. Since there are two major geo-hydrological entities in the basin, we would deal with them separately. The groundwater condition in alluvial areas of the basin had undergone dramatic changes during the past forty years, though significant variations are found in the pace at which change have taken place across different parts of the basin and in the present condition of groundwater due to several factors. Two important factors are the availability of surface water resources for irrigation, rainfall, and the quantum of recharge from rainfall. For instance, water level drops and the transition from open well pumping to dug-cum-bore wells and deep tube well pumping were very slow in large sections of Ahmedabad and Gandhinagar due to the availability of canal water9 and moderate rainfalls, in the first case and recharge from monsoon flows in Sabarmati river. In the early sixties, abundant groundwater was available in the upper phreatic aquifers of the area, which is nearly 100 feet deep. Though official data on the static water levels could not be obtained, farmers reported water level depths in the range of 40 feet in their open wells, which tapped the shallow aquifers. Extraction was done using bullock power. During 1970-85, farmers shifted gradually from open wells to dug-cum-bore wells and tube wells. While energised extraction started with diesel engines in the late 60s, electric motors and submersible pumps were introduced by the mid seventies. Maximum number of tube wells were drilled during the mid eighties. These tube wells tapped the confined layers of the multi-aquifer system lying below the water table aquifer. Analysis of data collected from ten well owners (at present) in two villages, namely, Ode and Jetalpur showed a mean depth to water level of 59 feet in 1970 for eight wells that existed then. By 1975, one dug-cum-bore well and three tube wells replaced four open wells. A new open well was also dug. The mean depth to water level in three sample tube wells was 90 feet in 1975, 8
9
For instance, in Kheralu taluka, the stage of development came down from 302 per cent to 128 per cent. Similarly, in Sanand taluka, it came down from 144 per cent to 112 per cent. In Idar, it came down to 110 per cent from 154 per cent. Canal water not only helped reduce the extraction from groundwater, but also contributed to recharge.
12
while that in one dug-cum-bore well was 80 feet. In 1985, two of the five open wells were converted into dug-cum-bore wells and the rest three were replaced by tube wells. The mean water level depth was 120 feet (for 6 tube wells). By 1990, all the 9 nine wells had been replaced by tube wells with an average water level depth of 163 feet. This declined further to 259 feet by 2000. Thus the decline in piezometric levels of confined aquifer could be as high as 170 feet (50 metres) during 1975-2000. The average annual drop in piezometric levels is two metres. One could also make a reasonable estimate about the decline in water levels in the shallow aquifer as 40 feet (12 metres) during the 15-year period from 1970 to 1985. A similar analysis carried out for 20 sample tube wells in three villages, named, Amrapur, Mubarakpur and Arjunpura in Kalol taluka of Mehsana showed the same groundwater level trends. In 1970, 9 out of the present 20 tube well owners had open wells and one had a tube well. By 1975, two of the open wells got replaced by tube wells. In addition, one dug-cum-bore well was established. By 1985, six out of the seven dug wells got replaced by tube wells. Five new tube wells were drilled. By 1990, 19 farmers had tube wells. The mean depth to water level in the tube well increased consistently from 150 feet in 1970 to 183 feet in 1975 to 227 feet in 1985 to 235 feet in 1990 to 297 feet in 2000. However, these observations of water levels are for the pumped wells. As the pumping wells experience drawdowns due to heavy withdrawal, the water levels in the pumped well may not fully represent the regional groundwater. The drawdown curve fades out only when the discharge is adjusted to the pumping through the diffusion process. The time taken for stabilisation (diffusion) depends on the dimension of the aquifer being observed and the hydraulic diffusivity of the aquifer10. Since the density of tube wells in the area is very high (one in every 0.5-1.0 sq. km area), and the permeability of the aquifer system being very high, stabilisation will not take long. Therefore, we can safely assume that the water levels in wells represent the regional groundwater table reasonably well. At the same time, the process was very rapid in Kalol and Vijapur areas of Mehsana, which form part of Sabarmati basin. Trends in Piezometric Levels in Sabarmati Basin Area The data on water levels obtained from the Central Ground Water Board (West Central Region) recorded by the automatic water level recorders established in three stations in Sabarmati basin area available for the months of January, May, August and November were analysed to understand the hydrodynamics in the area. These piezometres actually tap the confined aquifer just below the water table aquifer in the deep alluvial areas (Bavela and Ingoli), and shallow water table aquifer in the case of hard rock areas (Danta). Data on depth to water level were available only from May 1996 onwards till January 2000 for three stations - Bhavela and Ingoli in Dholka taluka of Ahmedabad and Danta in Danta taluka of Banaskantha district. These piezometres record the water level trends in the deep confined aquifers of the area. The water levels showed declining trends in all the three stations (Figure 2). In the case of Bhavela, the level declined from 12.95 to 16.02 metres during May 1996-January 2000. The maximum drawdown was observed during November 1997 to January 2000, and was of the order of 5.52 metres. In the case of Ingoli, the drawdown during the same period was 4.55 metres. For Danta, which had a shallow aquifer, the decline in water level was of the order of 4.19 metres. Such heavy drawdowns are primarily due to the heavy withdrawals that have taken place during the three consecutive years of drought from 1998 to 2000. 10
The time of diffusion is measured as t = L /D, where the value of varies from 0.25 to 0.50 in most cases, L is the measure of the dimension of the groundwater flow system being observed, and D is the hydraulic diffusivity. 2
13
1-Jan-00
1-Nov-99
1-Aug-99
1-May-99
1-Nov-98
1-Aug-98
1-May-98
1-Jan-98
1-Nov-97
1-Aug-97
1-May-97
1-Jan-97
1-Nov-96
1-Aug-96
Depth to Water Table
1-May-96
The water level trends in the first confined aquifers during the year 1995-2000, as per the data recorded by the limited 0.00 number of piezometres supplied 2.00 by CGWB for Sabarmati basin, 4.00 6.00 are moderate. This project 8.00 covered mostly those areas 10.00 12.00 which receive canal water for 14.00 irrigation and where serious 16.00 Bavela Danta Ingoli over-draft problems do not 18.00 occur. The data of automatic Figure 2: Water Level Fluctuations in the Observation Well water level recorders located in in Bavela, Danta and Ingoli problems areas were, however, not available for public use. However, according to the report titled ―Declining Groundwater Levels in the Deep Aquifers of Gujarat‖ prepared by the Central Ground Water Board: ―An analysis of the long term decline shows that in this aquifer, large declines even up to more than 70 metres have taken place over the period of nearly one and a half decade. The hydrographs of several other piezometres also indicate declines in the range of 30 to more than 50 m during the last two decades, especially in Ahmedabad, Gandhinagar and Mehsana districts.‖ Again, in the first confined aquifer in the central parts of North Gujarat, especially Ahmedabad and Gandhinagar, the water levels have undergone average annual declines in the range of 4-6 metres during 1996-2000 (CGWB, 2000). Almost the same rate of decline in water level is also found for the second confined aquifer underlying central parts of North Gujarat extending over Gandhinagar, Ahmedabad and Mehsana. Such large drops in water levels could have led to an increase in pumping depths and major reductions in yield of wells. This could also result in burning of motors or failure of tube wells due to sand rushing and other factors. Consequently, farmers will either have to invest in higher capacity pumps or lower new ―columns‖ for lifting the water, or invest in a new tube well. Water Level Trends in Open Wells in Sabarmati Basin Area
1-Jan-00
1-Aug-99
1-Jan-99
1-Aug-98
1-Jan-98
1-Aug-97
1-Jan-97
1-Aug-96
1-Jan-96
1-Aug-95
1-Jan-95
Depth to water level (M)
The water level data of open observation wells obtained from the Central Ground Water Board were also analysed to understand the dynamics of water Figure 3: Water Level Trends in Open Wells in Sabarkantha level in the shallow aquifers. The analysis of data for the observation Gamdi Harsol 18.00 Meghraj Shamlaji wells located within Sabarkantha 16.00 Vijaynagar 14.00 district available for the five-year 12.00 period from 1996 to 2000 shows 10.00 8.00 declining trends in water levels 6.00 from year to year (Figure 3). In the 4.00 case of an observation well in 2.00 0.00 Gamdi village, the depth to water level consistently increased from 3.39 metres in May 1996 to 10.5 metres in May 1999 with a total drop of 7.11 metres in four years. In the case of Vijayanagar observation well, the total drop was 14
1-Jan-00
1-Aug-99
1-Jan-99
1-Aug-98
1-Jan-98
1-Aug-97
1-Jan-97
1-Aug-96
1-Jan-00
1-Aug-95
1-Jan-96
1-Aug-99
1-Jan-95
1-Jan-99
1-Aug-98
Depth to water level (m)
1-Jan-98
1-Aug-97
1-Jan-97
1-Aug-96
1-Jan-96
1-Aug-95
1-Jan-95
Depth to water level (m)
only 1.27 metres. In the case of Meghraj, the drop was 2.04 metres during the same period. In the case of Hansol, though the May-May fluctuation in water levels during 1996-99 was zero, the JanJan difference in water levels was 12.6 metres during the five-year period. Maximum drawdown in the well had occurred during the drought of 1999 when the water levels had further dropped during the monsoon instead of recovery owing to the lack of sufficient rainfall. Now, the groundwater balance for Vijayanagar, Bhiloda and Meghraj shows only 80%, 86% and 94% development respectively during 1992-1997. Contrary to this, May-May water levels in Vijaynagar, Samlaji (Bhiloda), and Meghraj show declining trends at the average rates of 2.82 metres, 1.33 metres and 3.31 metres respectively during 1995-97. An interesting observation with regard to the water level fluctuations is the high seasonal fluctuations owning to the recharge and abstraction in comparison to the year to year fluctuations. For instance, in the case of Vijayanagar well, the water level dropped by 7.71 metres from August 1995 to May 1996 owing to pumping; but recovered by 7.27 metres during May 1996-August 1996 owning to the recharge from rainfall. More or less a similar trend continued in the next year. The water level dropped by 6.2 metres during August 1996-May 1997; then rose by 6.8 metres during the monsoon. It is very likely that the shallow wells may have dried up. On the other hand, the water level fluctuation over a four-year period was found to be only 1.27 metres; an average annual drop of 0.32 metre. This is one of the characteristic features of hard rock areas. Large seasonal drops in water levels (up to 25 0.00 metres) can have significant impact 5.00 on water availability in the wells Ghatlodia during dry seasons. 10.00 The observed water level 15.00 trends in the open wells in alluvial 20.00 areas are different from the open Figure 4: Water Level Fluctuations in Open Wells wells in the hard rock areas. Figure 4 in Ghatlodia, Ahmedabad shows the water level trends in an observation well in Ghatlodia village of Ahmedabad. The total drop in water level (from January 1995-January 2000) was 4.25 metres in six years, i.e., an average annual drop of 0.70 metre. Though in this area, groundwater withdrawal and recharge are precariously balanced (abstraction 123 per cent of the recharge), almost all the abstraction is from the lower aquifers, and the upper unconfined aquifer, which receives the direct recharge from top is not pumped as open wells Figure 4: Water Level Fluctuations in Open Wells in Kheda, are dry. Then the hydrodynamics, 1995-2000 as reflected in the hydrograph (Figure 4), could be attributed to the interaction between the upper 0.00 aquifer and the tapped underlying 2.00 aquifer wherein the water from 4.00 upper aquifer could be 6.00 Anand Bandhani 8.00 contributing to the lower one. To Nadiad Linear (Bandhani) 10.00 analyse the hydrodynamics in the Linear (Anand) 12.00 area due to excessive pumping, the hydrographs of piezometric levels in the tube wells in the area which tap the lower aquifer should be analysed. Unlike in the case of 15
hard rock areas, the seasonal drops are not very significant. A maximum rise in water level of the order of 3.74 metres was observed during 1999 when there were floods in Ahmedabad. At the same time, water levels in the open wells in Kheda district did not show any recession during the past five years. On the contrary, the levels had slightly risen (Figure 5). For example, in Bandhanai observation well, the water level showed a rise of nearly 1.2 metres from 4.9 metres in May 1995 to 3.72 metres in 1999. In the case of an observation well in Nadiad, the water level rose from 4.35 metres-5.6 metres during 1995-99. 4.2.3 Economics of Groundwater Over-exploitation The economic analysis attempted by us covers [i] extraction efficiency—how much groundwater can be extracted with every unit of energy (electricity or diesel) used?; and [ii] economics of groundwater extraction/development, i. e., how much does it cost to extract a unit volume of water from underground sources as compared to alternative sources of water and what are the potential returns? Extraction efficiency is a good indicator of whether the use of energy or fossil fuel for groundwater pumping is sustainable or not. Economics of groundwater development helps in decision-making with regard to investment priorities in water and in the selection of competitive alternatives (Custodio and Gurgui 1989; Howitt 1993). In the areas where large-scale exploitation of groundwater had led to undesirable consequences, such analysis provides a strong indication of whether groundwater is depleted to an extent that it is no more economically accessible. The variable costs should not only include the actual water cost (based on the actual cost of energy used for groundwater pumping), but also the indirect costs such as the social and ecological costs of using fossil fuel and water (where ever applicable). After Custodio (2000), in many cases, what is called economic analysis includes only the actual water cost and is used mainly to decide if it is advisable to proceed with the planned development, to introduce variations or to look for subsidies to reduce the water cost for the consumer. In the real sense, farmers in Gujarat are not paying the actual cost of generation of electricity used for groundwater pumping, i.e., the use of electricity for pumping water for irrigation is subsidised. However, the extent of subsidy enjoyed by the farmers varies widely and depends on the availability of groundwater supplies which a farmer can tap and the number of hours for which power supply is available (IRMA/UNICEF 2001). Therefore, if we consider the price farmers are paying for electricity used for groundwater pumping, the benefits are likely to be inflated. Secondly, there were no attempts to quantify the social and environmental effects of using non-renewable groundwater and such effects were never considered in economic evaluation. The extraction efficiency is inversely proportional to pumping depth and directly proportional to pump efficiency. As the pumping depth increases, the energy, which is required to pump a given quantum of groundwater, increases. With an increase in mean depth to water levels in tube wells from 90 feet to 260 feet (during 1975-2000), i.e., 50 metres, the extraction efficiency will be reduced to just one-third the 1975 levels (33 per cent), provided the pump efficiency remains the same. Under natural circumstances, the efficiency of the pump will reduce over time and therefore, the extraction efficiency will be much lower than 33 per cent of the 1975 levels. The economics of groundwater irrigation depends on the fixed cost of the irrigation system and the life of the system, the variable cost of water, and the returns from irrigated farming. The values of these parameters had increased remarkably over a period of time, owning to the drastic changes in the hydrological setting groundwater, resulting from continued exploitation. We will now examine what has been the net effect of these changes on the economics of well irrigation. 16
Hours of Irrigation
First: The fixed cost of the irrigation system has increased dramatically over the last 25 years from one lakh rupees in 1975 to nearly 4 lakh rupees today (2000), which is mainly attributed to the increase in the depth of tube wells. This is not a major increase when we consider the time value of money. But, when we consider the fact that drilling has become quite inexpensive due to the easy availability of drilling rigs and competition amongst drilling companies in the recent times, such a rise is quite enormous. The average depth of tube wells has gone up from 294 feet in 1975 to 524 feet in 2000. Higher depth of wells requires higher depth of drilling, higher capacity submersible pumps, and higher investment for all other mechanical installations including well casing and strainer pipes. Second: the variable cost of water includes the direct cost of energy used for water extraction and the indirect cost (social and environmental) of Figure 6: Historical Changes in Time Spent on mining water. The direct cost has Irrigation increased over the 25-year period 400.00 Kharif Paddy Wheat from 0.22 rupees per cubic metre Alfalfa Fodder Jowar in 1975 to 0.33 rupees per cubic 300.00 metre in 1985 to 0.41 rupees per 200.00 cubic metre in 1990 to 0.59 rupees per cubic metre in 2000. Even if 100.00 one assumes that the water 0.00 application rate for a given crop 1970 1975 1985 1990 2000 does not vary with time, by the year 2000, the cost of irrigation water had increased by 270 per cent over the 1975 levels. The social and environmental costs of water abstraction increase as one goes deeper due to the increased use of fossil fuel and fossil water. One of the social imperatives is that with increased mining of water, the drought proneness of the region increases. Secondly, the farmers have to spend more time in irrigating their crops as water table declines due to several factors that are linked to depletion: increase in frequency of watering (which will be dealt with in the section on ecological impacts), reduction in well yield etc. While it used to take an average of only 22 hours in 1970 to irrigate one hectare of paddy, it takes 110 hours in 2000 for a paddy field of same size, i.e., nearly five times. In the case of fodder jowar (summer), the total hours of irrigation went up from 66 per hectare in 1970 to 122 per hectare in 2000 (Figure 6). One of the reasons for this could be the vast change in soil moisture regimes, which took place over the years. Farmers in the region practice flood irrigation for paddy and therefore have to irrigate excessively to create pounding of water. The opportunity costs, both social and economic, associated with spending extra hours in the field for irrigation need to be taken into consideration while evaluating the costs. Third: the economic returns from irrigated farming (exclusive of cost of irrigation) have reduced over a period of time due to: [a] reduction in area under irrigation (which is the result of both reduction in well yields and the increase in irrigation water rate for different crops); and [b] increase in cost of inputs. We will examine each one of these variables separately in the following section. As Table 2 indicates, the mean yield of the tube wells has gone down from 157 cubic metres per hour to 78 cubic metres per hour, though the average pump horsepower had increased from 23.3 HP to 31 HP. The average area under irrigation for the tube wells had come down from 16.38 acres to 10.79 acres.
17
Table 2: Economics of Tube-well Irrigation in the Alluvial Area of Sabarmati Basin Particulars Paddy Area (Ha) No. of Irrigation Hrs. of irrigation (hrs/ha) Cost of water pumping (Rs/Hr) Cost of pumping (Rs./Ha) Cost of Cultivation without water (Rs/Ha) Total Production for irrigated crop (Qt./Ha) Total production for rain-fed paddy (Qt/Ha) Market price (Rs/Kg) Cost of cultivation for irrigated crop (Rs/Ha) Cost of cultivation for rain-fed paddy (Rs/Ha) (80%) Gross income of irrigated crop (Rs/Ha) Gross income for rain-fed paddy (Rs/Ha) Net income from irrigated crop (Rs/Ha) Net income for rain-fed crop (Rs/Ha) Net income from crop (Rs/Ha) Total Area (Ha) Total net income (Rs) Total income from different crops (Rs) Cost of repairing and maintenance of pump (Rs/year) Cost of water Net income (Rs) Value of PVIFAk,n @10% for 12 year Total income for 12 year (Rs) exclusive of water Total cost of water for 12 years Volume of water pumped Total environmental cost of using water Cost of installation of pump (Rs) Cost Benefit Ratio – inclusive of Environmental Cost Cost Benefit Ratio – exclusive of Environmental Cost
Name of the Crops Alfalfa Wheat Jowar (Fodder) (Fodder) 1.00 1.00 1.00 14.25 5.30 6.8 21.9 18.2 16.8 116.3 116.3 116.3 36262.2 11188.8 13315.2 5871.7 8276.3 5707.0 306.3 34.6 504.5
1.00 5.80 18.8 116.3 12689.4 11384.8 40.3 20.0 700.0 100.0 600.0 24074.2 42133.9 19465.1 9107.8 28183.4 30625.0 20745.0 14000.00 16798.60 24753.29 12468.8 4892.2 0.0 0.0 11906.4 24753.3 12468.8 7.5 0.4 7.3 89179.2 10396.4 90897.2 205025.7 10000.0 95043.5 15230.1 81566.6 195025.7 6.81 1328905.3 1611911.0 62953.5 10087.9 54026.9 320302.3 350000.00 1.72 0.80
80.0 19022.2 40356.8 34649.8 0.0 34649.8 0.4 14552.9
5592.4
3704.2
Taking these variables into consideration, we carried out a comprehensive analysis of economics of well irrigation. Our analysis is based on the following assumptions: [1] the average life of the tube wells is 10 years; [2] the direct economic cost of pumping water will increase consistently during these 10-years proportional to the rate at which pumping depth increases; and [3] the environmental cost of using groundwater from deeper aquifers will also increase proportional to the rate of increase in pumping depth. The economic value of the environmental cost of water (per cubic metre) is tentatively taken as 0.35 rupee. However, we have not incorporated the potential reduction in the area under irrigation, which might occur due to the reduction in yield of wells due to lowering of water levels. The economic analysis shows that the net economic return from tube well irrigation would be negative (B/C ratio is 0.80), even if one does not includes the economic value of the environmental costs associated with exploiting the non-renewable groundwater. The net economic loss will be more (B/C ratio is 1.72), when we include the environmental cost of the pumped water. This means, as time passes, tube well irrigation will become totally unviable in the deep alluvial areas inside the Sabarmati basin. 18
4.2.4 Social Aspects Groundwater over-development has several social implications. One of the primary social objectives is to provide adequate quantities of good quality water for drinking and domestic purposes. Security of rural livelihoods could be another. The social impact of groundwater exploitation would, therefore, include: the changes in groundwater availability for drinking and domestic purposes in terms of quantity and quality its due to over-exploitation; changes in livelihood patterns of the farming community; and patterns of migration caused by water scarcity. Groundwater over-draft has severely affected the sustainability of drinking water sources in a large part of Sabarmati basin area. First: in the hard rock areas, the overall availability of groundwater is limited. Water being very scarce, there is severe competition for its use for irrigation and drinking purposes. Second: in spite of the fact that drinking water is a high priority demand, the unique nature of this demand places it in a less advantageous position as compared to irrigation demand. While demand for drinking water is more or less evenly distributed across the year, the irrigation demand is highest during winter, followed by summer. A lion’s share of the available water in the shallow aquifers of the area gets drawn up for irrigation through the hundreds of thousands of farm wells during the winter season. Due to large seasonal drops in water levels of the order of 6-7 metres, by the end of the winter, the open wells and hand pumps, which are the community water sources, get dried up. The rich farmers in the area manage to drill vertical bores to provide protective irrigation to their summer crops, the poor farmers have to leave their lands fallow. Drinking water becomes a scarce commodity for the poorer sections of the community in the villages. The shortage of water becomes acute during droughts as water levels drop further in the wells during the monsoon season itself (Figure 3). In such situations of absolute water scarcity as encountered during the past two years (1999-2000), several hundreds of villages in Sabarkantha district which fall within the Sabarmati basin area were supplied drinking water by tankers. The poor farmers in this region have to migrate to other perennially irrigated areas in search of employment. In the alluvial areas, excessive withdrawal of groundwater from the deep aquifers had resulted in contamination of freshwater aquifers with fluorides and salts. This also had severe adverse impact on the availability of good quality groundwater for drinking. 4.2.5 Ethics of Water Use Groundwater use--like the use of other natural resources--involves certain ethical considerations (Custodio 2000). The phenomenon of groundwater over-exploitation and mining, therefore, needs to be assessed from the point of view of water use ethics. If water from a regional aquifer in an arid or semi-arid region is extracted using unethical practices, then the aquifer is most likely to be mined. The question is: how does one determine whether ethical practices are followed in water extraction and use or not? How does one differentiate ethical from unethical practices? Answers to such questions are beyond the scope of natural sciences, engineering and economics. The fact is that the groundwater crisis—in the form of overall scarcity of water, and inequitable access-- emerges as a result of lack of solidarity among farmers and other water users, unsustainable use and pollution. Therefore, any use of water, which jeopardises this solidarity among water users who are sharing a ―common good‖, threatens the sustainability of water use, or causes pollution of freshwater resources can be called ―unethical‖. The ethical considerations concerning water use mainly revolve around the distribution of benefits and costs of water use and 19
risks associated with it (Llamas and Priscoli 2000). Possible lines of investigation of these issues are as follows: Whether farmers are engaged in wasteful irrigation practices using more water and also using drinking quality water for irrigation? Are farmers engaged in water extraction practices that reduce the opportunities of their neighbouring farmers or the individual himself or other water users to abstract water from the common aquifer - deeper tube wells, higher capacity motors than what is needed? Do farmers have the tendency to pump water at the same time?; and Are water users and others engaged in polluting freshwater aquifers that endanger other uses? Do the official agencies maintain transparency by compiling and providing reliable data about groundwater resources potential and conditions to the potential users and other concerned citizens? Following are our observations on the above-mentioned questions in the context of Sabarmati basin. First: farmers are engaged in irrigation practices that are quite wasteful. Our analysis shows that the rate of water application by farmers is much higher than the actual irrigation requirement of the crops. This is due to the lack of adoption of appropriate soil management and on-farm water management practices. This leads to applying water more frequently and in larger depth to take care of the excessive percolation, runoff and evaporation losses from the farm. Second: farmers are engaged in a competition to abstract water from the underground aquifers. The power supply is available to farmers for a limited number of hours. Due to this reason, they start their pumps as soon as the supply is restored. Simultaneous pumping by a large number of farmers lead to excessive drawdowns within a short span of time at the regional/local level in the hard rock areas. This leads to temporary drying up of shallow wells, mainly affecting the poor farmers. They have to then wait for a few hours for the wells to recuperate. This reduces the opportunities of poor farmers for irrigating their fields. Third: a large number of industries, which generate hazardous effluents and which do not want to invest in treatment systems, are resorting to pumping their effluents into the underground formations using inverted bore wells. This leads to contamination of the aquifers. This practice has been going on for quite some time in the industrial area of Odhav in Ahmedabad. Finally, the way groundwater exploitation is perceived also involves ethical considerations. The official perceptions of groundwater over-development/ over-exploitation are ―absolute‖ and not distributive or ―relative‖. According to the UNESCO Working Group on Ethics in Freshwater Use, as quoted in Llamas and Priscoli (2000), to view water crisis in absolute terms is ethically insufficient and one must also view it in relative terms as the two different perceptions (absolute and relative) lead us to different ethical norms. The same concept can be applied to groundwater over-exploitation also. Apart from describing the ―absolute consequences‖ of over-exploitation problems such as drops in water levels and quality problems, the official agencies must also describe the ―distributional/relative consequences‖. Some of the distributional consequences are denial of access to water by the poor and inequitable access to water resulting from disproportionate distribution of the benefits of electricity subsidy. 20
4.2.6 Ecological Consequences Ecological consequences are analysed by studying the extent of land degradation, and changes in the feasibility of growing agricultural crops. [a]
Land degradation
Land degradation is caused by water logging, and salinity, breaking of soil structure, soil retention capacity and loss of organic matter and nutrients, and increase in soil salinity. Waterlogging and Salinity
1-May-99
1-Aug-98
1-Jan-98
1-Aug-97
1-Jan-97
1-Aug-96
1-Jan-96
1-Aug-95
1-Jan-95
1-Aug-94
1-Jan-94
1-Aug-93
1-Jan-93
1-Aug-92
1-Jan-92
1-Aug-91
Like lowering groundwater levels, rising groundwater levels is also an undesirable consequence of improper utilisation of groundwater resources. A large part of the irrigated area in Watrak sub-basin is under Mahi command in Kheda district. A part of this canal command is facing problems of water logging due to rising water levels resulting from under-utilisation of groundwater, and seepage and percolation of water from excessive irrigation and poor drainage. Moderate to high rainfalls and semi-humid climate, which keep the irrigation requirements low, and clayey soils increase the vulnerability of the area to water logging. Figure 7 shows the graphical representation of water level trends in four observation wells
Borsad I Matar II
Depth to water level
0 2 4 6 8 10 12
Petlad Thasra Linear (Matar II) Linear (Borsad I)
Figure 7: Water Level Fluctuations in Sample Wells in Mahi Command
in Matar, Petlad, Borsad and Thasra talukas of erstwhile Kheda district. The water levels in none of the wells have shown a declining trend. On the contrary, in 3 of the wells, the water levels have risen during the period, 1991-2000. The maximum rise in water level was found in the open observation well in Matar taluka, which is worst affected by water logging problems from nearly 6.0 metres in May 1992 to 4.0 metres in May 1999. Though such water levels are not dangerously high from the point of view of agriculture, large chunks of land in the area have already become unsuitable for irrigation. In the case of Thasra, though there was no significant change in water levels in the open wells, the depth to water level remained in the range of 1.5-2 metres during the peak of May. Such a high water table is quite alarming from the point of view of maintaining crop health. Five talukas of erstwhile Kheda district are facing the problem of waterlogging due to excessive irrigation. They are Matar, Petlad, Khambhat, Thasra and Nadiad. They all fall within the Sabarmati basin. According to official data, nearly 1.7 per cent of the command of Mahi irrigation scheme had water table within 1.5 metres in 1995, as against 1.1 per cent in 1989. 21
Almost 60 per cent of this area is in Matar taluka, which falls inside Sabarmati basin. Nearly 17 per cent of the command had water table within a depth of 1.5-3.0 metres in 1995 as against 8.9 per cent in 1989. About 70 per cent of this affected area is in Khambat and Matar talukas (Mahi Irrigation Circle, Nadiad). The area under waterlogging increases after monsoon. According to the data provided in ORG (2000), the area, which had water table within 1.5 metre, ranged between 6,423 ha in the pre-monsoon to 16,872 ha in the post-monsoon of 1996. Field surveys carried out in one village, named, Machchel in Matar taluka, one of the worst affected areas, brought to light the process of ecological degradation. Canal water was first introduced in the area in 1964-65. Prior to this, the area had shallow groundwater table in the range of 30-40 feet. The farmers used to tap water from the shallow aquifer using open wells. Paddy was the main crop, which was largely rain-fed. With the introduction of canal water, farmers started taking irrigated crops in all the three seasons. With the availability of cheap canal water, farmers stopped well irrigation. Return flow from canal irrigation, and natural recharge from rains, with no withdrawal, led to a gradual rise in groundwater levels in the area. This also brought salinity to the soil surface. The farmers in Machchel village, however, were of the view that a major imbalance/mishap in the groundwater ecosystem occurred in just one year during early 1970’s when the entire region was marooned due to heavy monsoon rains and water released from Mahi canal system. Due to the poor surface and underground drainage, the entire water percolated down bringing groundwater to the surface. This resulted in the mixing of groundwater in the upper layer with that in the lower ones, which resulted in increased salinity of groundwater in the upper layer. The farmers were of the opinion that the groundwater in the lower layers is highly saline due to the close vicinity of marine deposits. The analysis of water sample collected from an observation station in Shekhpur of Matar taluka establishes this. It shows TDS values as high as 3480 ppm and 4200 ppm in May 1997 and May 1999 respectively (source: data from Central Ground Water Board, West-Central Region, Ahmedabad, 2001). The evaporation of groundwater through the soil surface resulted in deposition of salts and increase in soil salinity. For the past several years, the land has become totally unsuitable for cultivation. A large area under Mahi right-bank canal command is already affected by salinity due to waterlogging. They extend over five talukas of the district, which are facing severe problem of waterlogging. However, major differences exist in the available figures on the extent of salinity in canal command areas. Mahi command is not an exception. According to the latest data compiled by the Operation Research Group (1999), the area under waterlogging ranges between 21,873 ha in post-monsoon 1996 to 24350 ha in pre-monsoon 1997 (ORG 2000). The study done by CSSRI estimates the total salinity affected area in Mahi irrigation command as 13,800 hectares (Dubey et al. 1999). In Machchel, a total of nearly 400 hectares out of 480 hectares of cultivable land had been affected by water logging and salinity. This land is now not suitable for cultivation of any agricultural crops. The lands which are most severely affected are those having heavy soils. These soils have very poor drainage. Poor surface drainage was also found to be one of the reasons for aggravation of waterlogging problems in the area. During heavy rains, both the water released from the canals and the runoff gets accumulated in the fields. This leads to flooding of the fields. This water eventually percolates down through the soil to reach the groundwater table resulting in rising water levels.
22
Breaking of Soil Structure, Soil Retention Capacity and Loss of Organic Matter and Nutrients
Fertiliser (Kg/Ha)
One of the consequences of groundwater level drops and drying up of shallow aquifers is the introduction of tube well technology. As the open wells were no more viable for tapping water from the deep layers of the aquifer system in the alluvial areas, farmers had to shift to tube well irrigation. Though tube well irrigation was costly for the farmers, the technology turned out to be a blessing in disguise for them in the initial years. Tapping of groundwater from confined systems through tube wells resulted in higher well yields throughout the year and round the clock. Unlike in the case of dug wells, which provided limited quantum of water only seasonally, in the case of tube wells, the yields were not affected by continuous extraction and due to seasonal changes in natural recharge. The immediate impact of this was the Figure 8: Historical Changes in Fertilizer expansion in area under irrigated Application, Daskroi, A'bad 500.00 crops and cultivation of irrigated Paddy Alfalfa Wheat] Fodder Jowar 400.00 summer crops. The land, which used to receive irrigation water only 300.00 once in a season, started getting 200.00 water in most of the cases in two 100.00 seasons and in a few cases in three 0.00 seasons. 1970 1975 1985 1990 2000 The excessive irrigation resulted in leaching of minerals and organic matter in-to the soil. As the irrigated area increased, the availability of organic manure per unit area of cultivated land got reduced substantially. Chemical fertilisers had to be used in greater quantities. This, in a way, substituted for the organic, bio-fertilisers, which fell far short of the requirements. The chemical fertilisers enhanced the secondary productivity of the soils. On the other hand, the organic fertilisers were necessary to maintain the soil structure; provide necessary soil nutrients; and maintain the primary productivity of the soils. Increased fertiliser use also became necessary for modern farming using green revolution, hybrid varieties. Figure 8 shows the historical changes in the intensity of fertiliser application for three major crops in Daskroi taluka of Ahmedabad. The bars show the rising trend in the use of fertilisers (urea and di-ammonium phosphate) per ha of land. The highest increase in the rate of fertiliser application was observed in the case of paddy. It went up from a mere 137 kg/ha in 1970 to 404 kg/ha in 2000. The intensive use of fertiliser was accompanied by increased rate of application of irrigation water. This resulted in breaking of soil structure. In a nutshell, three major changes in land use occurred and had serious implications for land productivity; increase in cropping and irrigation intensity; increased rate of water application for each of the irrigated crops; and increased rate of application of fertilisers. Increase in Soil Salinity Resulting from Irrigation with high TDS Water While waterlogging has been one of the causes of soil salinity in the command areas, irrigation with saline groundwater is leading to soil degradation in the groundwater irrigated areas in the basin. A study carried out by GUIDE (2000) cites groundwater over-exploitation as one of the major causes of inland salinity in Gujarat, like increased use of fertilisers, and lack of soil nutrient management practices (Singh et al. 2000). The water from deep aquifers generally has high levels of total dissolved solids (TDS). The analysis of pre-monsoon water samples collected from selected piezometre stations shows high 23
TDS in groundwater in a few of the stations that are located in the alluvial areas (Table 2). For instance, in the case of Baola in Dholka, the TDS of water samples during May 1995, 1997 and May 1999 were 4080 ppm, 3300 ppm and 3156 ppm respectively. In Kheda, TDS values of 2580 ppm and 2460 ppm were observed. All these values are far above the permissible TDS level of 1500 ppm for use in irrigation. Pumped groundwater in Ahmedabad and surrounding areas has recorded TDS levels far above the permissible levels. The water samples collected from the observation wells in the hard rock areas showed TDS levels much lower than the permissible levels for irrigation. Table 3: TDS and Electrical Conductivity Values of Water Samples from Selected Observation Wells in Sabarmati Basin Area Name of the District/ Observation Years Observation Station May 1995 June 1995 May 1997 June 1997 June 1998 May 1999 A. Banaskantha 1. Danta 0.00 0.00 1008.00 0.00 0.00 1116.00 2. Vijaynagar 0.00 0.00 0.00 593.40 540.00 540.00 3. Karanpur (Bayad) 0.00 0.00 0.00 593.40 540.00 552.00 4. Sathamba (Bayad) 0.00 0.00 0.00 495.60 360.00 492.00 5. Bhiloda 0.00 0.00 0.00 882.00 720.00 660.00 6. Samlaji (Bhiloda) 0.00 0.00 0.00 744.00 720.00 744.00 7. Meghraj 0.00 0.00 0.00 504.00 420.00 426.00 8. Harsol (Prantij) 0.00 0.00 684.00 0.00 600.00 654.00 9. Varvada (Prantij) 0.00 0.00 0.00 1565.40 0.00 1740.00 10. Gamdi (Himatnagar) 0.00 0.00 0.00 417.60 420.00 972.00 B. Ahmedabad 1. Baola (Dholka) 4080.00 0.00 3300.00 0.00 0.00 3156.00 C. Kheda 1. Anand 0.00 558.00 0.00 522.00 0.00 480.00 2. Kapadwanj 0.00 0.00 0.00 864.00 0.00 840.00 3. Balasinor 0.00 0.00 0.00 438.00 390.00 420.00 4. Bhadran 1080.00 0.00 0.00 1080.00 0.00 1200.00 5. Shekhpur (Matar) 378.00 0.00 0.00 3480.00 3900.00 4200.00 6. Kheda 2580.00 0.00 0.00 2460.00 0.00 0.00 7. Nadiad 0.00 888.00 0.00 504.00 498.00 660.00 8. Bandhani (Petlad) 1380.00 0.00 0.00 900.00 1320.00 1470.00 Source: Central Ground Water Board, West-Central Region, Ahmedabad.
Farmers are continuing irrigation with the saline groundwater in these areas. Irrigation with high TDS groundwater is also leading to increase in soil salinity causing hardening of soil surface and lump formation. In order to break the soil lumps to enable better growth of crops, the farmers had to increase the water application rates. Thus, over a period of time, more salts get accumulated on the soil surface and thus the soils become saline. Excessive irrigation to leach the salts causes faster loss of organic matter and nutrients present in the soils. All these ultimately result in soil degradation. According to a study by Dubey et al. (1999), six talukas falling in Sabarmati basin account for 44,286 ha of salt-affected land in the State. This includes areas affected by both alkalinity (12,505 ha) and salinity (31,781 ha) in the districts of Mehsana, Ahmedabad and Kheda. Of the 24
total salinity-affected area, 9300 ha falls in the two talukas of Kheda that are also affected by the twin problem of waterlogging and salinity, namely, Matar and Khambhat. ORG (1994) estimated a figure of 10,757 ha as the total areas affected by salinity due to waterlogging in these two talukas, slightly more than the figure (9300 ha) provided by Dubey et al. 1999. Therefore, we assume that the entire problem of soil salinity in the two talukas of Kheda district, namely, Matar and Khambhat, is due to waterlogging alone. This leaves us with a figure of 34,986 ha as the land affected by salts in the talukas falling in Sabarmati basin area. The saltaffected soils are degraded soils and suffer from low primary productivity. It is striking to note that the salt-affected soils are concentrated in the alluvial areas, which are also having poor quality of groundwater in terms of high TDS, further strengthening the argument that groundwater degradation is the major cause of salts in soils. [b]
Changes in Feasibility of Growing Agricultural Crops
In areas where the shallow aquifers have dried up due to excessive withdrawal of groundwater, a major impact has been on the agro-ecology. The open wells in the area, which used to tap the shallow sandy, alluvial aquifer (which is subject to direct recharge from the rainfall) used to yield good quality water free from salinity. Vegetable cultivation was widely prevalent in the area around Ahmedabad (in Daskroi taluka for instance) till the mid-seventies. Vegetables like bitter gourd were extensively grown in the area. But as the shallow aquifers dried up, farmers had to depend on the groundwater from lower confined layers of the aquifer system. Water from these layers is of poor quality containing salts, indicated by moderately high levels of TDS. This water is found to be totally unsuited for vegetable cultivation. Due to the presence of salinity in the pumped groundwater, the soil gets hard on the surface. This prevents proper aeration of the soil. In order to break the soil lumps, farmers had to apply water excessively which is not favourable to vegetable crops. Farmers grow only wheat and paddy, which they feel is most suitable for growing these crops using bore well water. Further, salt resistance of paddy is very high. In the waterlogged areas, due to increase in soil salinity, a large portion of the land has become unsuitable for cultivation, while in the remaining areas, several of the crops which farmers used to grow in the past such as tuwar, til, desi kapas have now become un-viable. Farmers are now able to take paddy, wheat and jowar in kharif, winter and summer. 4.3
How and why Groundwater in Sabarmati Basin Gets Over-exploited?
One of the major causes of groundwater over-exploitation in Sabarmati basin area is the rapid energisation of abstraction structures such as the dug wells and the growth in deep tube wells, which have significantly enhanced the ability of farmers to abstract groundwater at faster rates. The following data corroborate these phenomena. In 1970-71, there were a total of 1,10,062 dug wells meant for irrigation in the 28 talukas falling in Sabarmati basin. The number of dug wells rose marginally to 1,15,486 by the year 199596, recording a 0.20 per cent annual compound growth rate. This means there was no significant growth in the number of dug wells over the 25-year period from 70-95. Further, the incremental abstraction contributed by the increase in the number of dug wells must have been quite insignificant due to the reason that the farmers could lift very little water from the manually operated-dug wells. However, the number of electrified wells increased from 15,024 to 64,948 over the same period of time. This amounts to an annual compound growth rate of 6 per cent. At the same time, the oil engines recorded a nominal overall growth of 0.20 per cent per annum. But a closer look shows that the number had been dropping from 1975-76 onwards. This means that 25
there has been rapid energisation of dug wells in the region, with the dug wells and dug well fitted with oil engines being replaced by electric motors. In addition to this, there has been a dramatic increase in the density of tube wells in the region. In fact, there were only 913 tube wells in the 28 talukas in 1970-71, which increased to 9473 by the year 1995-96, showing an annual compound growth rate of 9.8 per cent. This is a phenomenal growth. If one makes a reasonable assumption that one tube well in Sabarmati basin pump out 50 cubic metres of water per hour, and runs for 1500 hours per year (including winter and summer seasons), the additional abstraction due to increase in the density of tube wells alone is of the order of 640 MCM. Similarly, the introduction of electric motors could have significantly contributed to increasing the rate of abstraction of water through dug wells. In Sabarmati basin, the open wells are widely used in the shallow aquifer areas, especially Sabarkantha district and parts of Kheda
Dugwell Electrified Well Oil Engines Tubewell
10000 8000 6000 4000 2000
No. of Tubewells
160000 140000 120000 100000 80000 60000 40000 20000 0
1995-96
1990-91
1985-86
1980-81
1975-76
0
1970-71
Number of water abstraction structures
Figure 9: Growth in the Number of Wells in Sabarmati Basin
district. The average discharge of open wells fitted with a 5 HP motor is 10 litres per second, or 36 cubic metres per hour. But, unlike in the case of tube wells that tap the large alluvial aquifers, an increase in number of wells (open wells fitted with electric motors) does not lead to a proportional increase in the aggregate abstraction in hard rock areas. This is so because of the fact that the yield of individual wells starts declining beyond a certain level of well density in a certain area due to increasing well interference, a peculiar phenomenon in hard rock areas. This is reflected in reduction in yield hours of wells. The wells, which used to yield for 8-10 hours a day in the past, now yield for a total of 3-4 hours a day only. If we make a reasonable assumption that an electrified well in 1970-71 used to run for 1500 hours and the same runs for 600 hours a year now, the additional abstraction caused by the increase in number of electrified wells could be as high as 590 MCM. The root causes for excessive withdrawal of groundwater are many. Introduction of green revolution technologies such as hybrid varieties of paddy, wheat, bajra and jowar, and increased use of fertilisers encouraged increased dependence on irrigation water for growing crops. Introduction of cash crops such as cotton, castor and mustard to meet the micro-economic needs also increased the dependence on groundwater for irrigation. Further, to support the vibrant and the fast growing dairy economy, the farmers started growing highly water-intensive fodder crops such as alfalfa. Rural electrification and subsidised electricity for groundwater pumping in the farm sector which led to large-scale energisation of wells made this possible. Easy availability of deep well pumping technologies encouraged tapping of groundwater from deep aquifers. Unlike shallow 26
open wells, deep tube-wells ensured supply of groundwater throughout the year, and farmers took to intensive irrigated farming in all the three seasons. Subsequently, with the introduction of flat rate system of pricing of electricity in 1987, the marginal cost of abstraction of water became zero. Thus, in an effort to recover the high initial investment in tube well construction, and the fixed operating cost (the electricity charges), the farmer were encouraged to sell more and more water after meeting their own irrigation requirements. Every increase in the hours of pumping led to a reduction in the implicit cost of electricity and of water. 4.4
The Logic of Overexploitation of Groundwater11
Revenue & Cost
Groundwater is an open access resource for all those who own the land overlying it. Given its open access nature, increasing demand for it for various uses, availability of modern water extraction technology, the finite quantity of its stock as well as the finite recharge rate, groundwater is bound to be over-exploited and its use sub-tractable/competitive, i.e., if one of the co-users uses more of it, the less is left to that extent for the other co-users. In resource economics, this phenomenon is known as interdependence of the underlying production functions and is an indicator of existence of externalities. An externality is defined as an unintended and uncompensated side effect of an activity. It is the presence of an externality in the use of an open access natural resource that gives rise to a problem called, albeit erroneously, by Hardin (1968) as ―the tragedy of the commons‖. The problem should correctly be termed as ―the tragedy of the open access‖. When an externality is present, the competitive equilibrium use of the resources (open access) is socially inefficient. We illustrate this with an example of a groundwater basin, which is an open access resource for the group of owners of overlying land. We presume that there are N identical owners of land overlying a particular basin each having a water extraction device (WED) and thereby having an access to the basin. Each land owner extracts only a very small fraction of the total stock of Figure 10: Competitive (open access) Equilibrium Level and Socially Optimal Level of Exploitation of water available in the basin in the Groundwater area and hence he cannot significantly affect the total stock of water available at a particular Social Marginal Cost point in time. We presume that there exists a well-developed market for groundwater in the Private Marginal Cost area and each water seller takes the current market price as constant. We also assume that the Marginal Revenue current market price of water does not change over time. X1 X2 Under the abovementioned assumptions, each Level of Extraction (X) rational (profit maximising) water extractor will try to extract as much of the water as he needs to irrigate his own crops and to sell to others. In doing so, he would reduce the quantity of water available to the other water extractors operating within the same basin/watershed. This shows that there exists the problem of 11
This section is taken from Katar Singh (1995: 70-72).
27
a negative externality which causes the water table to fall down that is turn leads to increased cost of water extraction and hence a loss of revenue to all the water extractors. Every rational water extractor behaves in the same manner. The consequence of this rational behaviour on the part of individual water extractor is disastrous for all the water extractors as a group or community in the sense that the basin is overexploited and every extractor’s revenue goes down. Why this happens can be explained in terms of divergence between the private marginal cost and the social marginal cost of water extraction, i.e., the existence of an externality. Each water extractor considers only his (private) cost of extracting water and not the cost of depletion of the basin (an externality), which he is inflicting on the other water extractors. This results in the private marginal cost of extracting water being less than the social marginal cost of extraction and therefore the competitive equilibrium level of groundwater exploitation being higher than the socially optimal level of exploitation. This is illustrated in Figure 10. As shown in the figure, the competitive equilibrium level of water extraction is attained when the level of extraction is X2 where the private marginal cost is equal to the marginal revenue and the socially optimum level of extraction is X1 where the social marginal cost is equal to the marginal revenue. Thus the open access equilibrium is attained at a higher level of extraction and hence a higher level of exploitation than the socially optimum level of exploitation, i.e., X2 > X1. 5.0
SOCIO-ECONOMIC AND ECOLOGICAL GROUNDWATER OVER-EXPLOITATION
CONSEQUENCES
OF
5.1
Declining Water Levels and Emergence of Water Markets and Other Socio-economic Institutions
One of the most striking impacts of groundwater depletion in North Gujarat has been on the ability of farmers to access the groundwater. North Gujarat encompasses a large part of Sabarmati basin. In the 60s and 70s, when groundwater levels were high, shallow open wells were the most common groundwater abstraction structures in the area. They served as the cheapest and the simplest source of instantaneous irrigation. As the extraction from wells increased with the introduction of energisation of wells, groundwater levels started dropping. But the poor as well as the rich farmers responded by deepening their wells. Well deepening was more common during droughts. However, this did not create much financial burden on the farmers, as they used family labour. The other members of the farming community also often helped in the form of free labour for well deepening, as this was the prevailing social custom. But, with the drying up of shallow aquifer, the resources and technology available with the poor farmers to extract groundwater became inadequate. The farmers had to dig up to 350 feet to get adequate water from the next lower layer. Open well construction was not feasible for such a large depth and tube wells had to be drilled. Tube well construction required sophisticated drilling machinery, which involved prohibitive costs. Further, the oil engines, and electric motors were not capable of lifting water from such large depths. Submersible pumps were needed for this. The progressive and the enterprising resource-rich farmers in the region aggressively adopted sophisticated technologies for sustaining and managing deep tube well irrigation. The poor farmers who could not mobilise the necessary funds for tube well construction lost access to groundwater. They had to depend on the well owners, who had extra water after irrigating their own fields, for sale. The well owners also found this as the most convenient way of recovering the large investments made for well construction. Thus water markets emerged and became extensive. The area served by water markets forms a significant portion of the total acreage irrigated by groundwater, particularly in the alluvial areas of Sabarmati basin. For instance, in Daskroi 28
taluka, the 10 well owners together sell water, which irrigates a total area of 29.3 hectares. This is an addition to 75 hectares of the well owners’ own land irrigated by the tube wells. This was the scenario in 2000, after two consecutive years of drought when the well owners’ own irrigation demand was very high. All of them had made sharp cuts in the sale of water to their neighbouring farmers in the drought year. According to the well owners themselves, the actual area served by water markets could be as high 60 hectares in a normal year. In Kalol taluka, out of the twenty tube well owners who were surveyed by us, eight were found to be selling water to their neighbouring farmers. The total area irrigated with purchased water was 49.15 hectares (in terms of time, it was 5000 hours), against a gross area of 132.5 hectares irrigated by the 20 tube wells. On an average, water sale by tube well owners was of the order of 630 hours per tube well owner. Water markets were found to be operating in two different ways. In the first case, the well owners charged the farmer on hourly basis for the water provided. The well owner and water buyer were ―loosely bonded‖ by an understanding that the well owner would provide water to the farmer, if he has any surplus after meeting his own requirements. Needless to say, such arrangements are resorted to when the well owner is not able to guarantee watering for the entire crop season. When the farmer needs water, he has to inform the well owner about his requirement well in advance. When there are more than one potential buyer, water is provided on ―first come first serve‖ basis. Often, the water buyers changed the source of supply after seasons depending on the convenience. In the second case, the well owner assures irrigation water to the cultivator for the entire crop season. In addition to water, most often, the well owner also provides fertilisers and other inputs to the buyer, who provide all the labour inputs required throughout the crop season and gets one-third of the gross return from the crop. Such inter-locked markets operate when the well owner himself does not have sufficient land to cultivate, but has enough of surplus water. As the well owners’ water selling potential increased, new players entered the market. The land-less farm labourers in the village started cultivating in the plots of large and medium farmers, who had sufficient land and water but lacked sufficient manpower to cultivate, as sharecroppers. The landowner provided all the inputs such as water, fertiliser and pesticides and tractor for ploughing. The sharecropper provided all the labour inputs, including timely watering of crops till the crop is harvested. In return, he got 1/5th of the total income from sale of the output. It was found, however, that the watering decisions were normally taken by the farm owners themselves. Such arrangements were also worked out in situations when the well owner was stationed outside the village and did not have enough family manpower available to take care of the land. Normally, such arrangements continue for a good number of years. Uncontrolled draft from the confined aquifers resulted in further increase in the depth to water levels in the tube wells –as much as 50 metres during the 25 years from 1975-2000 in the alluvial areas of Ahmedabad. Most of the tub-wells which were drilled in the mid seventies and the early eighties thus went out of use. The farmers in the area had invested in re-drilling and installation of new high capacity pumps. In certain other areas within the basin, where groundwater levels had undergone alarming drops, especially in Ahmedabad and surrounding areas, investment required for well construction had gone out of the reach some of the farmers. They got together to invest in partnership wells. The investment to be made by an individual farmer depends on the amount of land to be brought under the command of the system. Or, in other words, the amount of water an individual farmer will be entitled to use for irrigation will depend on his shareholding in the group. Normally, one bigha of land in the command is treated as one share. If the total cost of irrigation system works out to be 8 lakh rupees, and if the total command area is 200 bighas, then a farmer who has a holding of 2 bighas would need to buy two shares costing 4000 rupees. 29
Generally, a group of farmers get together to plan for and invest in a large groundwaterbased irrigation system. A typical system costs 6-8 lakh rupees, including the distribution network. The group constitutes a Management Committee consisting of 7-10 members for carrying out the management functions of the irrigation organisation such as fixing of water charges, water allocation decisions, ensuring operation and maintenance of the system, and recovery of water charges, and resolving conflicts. The Management Committee appoints a Secretary, normally a non-member for the purpose of collection of water charges and account keeping. The committee also appoints an operator whose main responsibility is to operate the pump throughout the seasons, distribute water and keep records of water delivery to each farmer. A large percentage of the groundwater irrigated areas in the alluvial areas of the basin, especially those in Kalol and Vijapur, are irrigated by tube wells, which are jointly owned by groups of farmers. A large percentage of the area under well irrigation in the alluvial areas of Ahmedabad and Kheda, which fall in Sabarmati basin, is served by water markets. In the initial years, the member farmers were able to get as much water as they wanted to irrigate their crops grown on lands, which were included in the command of the irrigation systems. A farmer who had a holding of two bighas of land in the command of a tube well partnership, I could get as much water as he wanted to irrigate that particular piece of land, and thus there was no restriction on the cropping pattern. However, as water levels declined alarmingly, and power supply became limited to 10-12 hours a day, the concept of ―limited water use rights‖ was introduced. In this particular system of water rights, the number of hours for which a farmer would get water per every single shareholding he owns in the command is fixed. The total hours per unit area of land are tentatively fixed on the basis of the maximum number of hours for which the well could run during the time gap between two waterings of the crops and the total command area. If the total command of the system is 100 bighas, the frequency of waterings 10 days; and if power supply is available for 12 hours a day, then each farmer would get 1.2 hours of irrigation per watering. In the same way, the total entitlement for the entire season is also decided. In some situations, the groups decide the total hourly allocation for every single share much before the starting of the crop season. 5.2
Impacts of Groundwater Degradation on Access Equity and Efficiency in Groundwater Use
5.2.1 Impact on Equity The impact of groundwater degradation on access equity can be analysed by comparing the opportunities available to different categories of farmers to derive economic gains out of irrigation water. Comparison of the price at which irrigation water is sold in the market, and the implicit cost of abstraction of groundwater for the well owners gives an important indicator of the degree of equity or inequity in access to groundwater for irrigation between water buyers and the well owners. Comparison of implicit cost of irrigation water across water sellers can give an indication of the degree of equity in access to groundwater for irrigation across well owners. The underlying premise in such an analysis is that the rich well owners are capable of adopting high capacity pumps, or mobilising resources to drill deep tube wells. By virtue of this, they have unlimited access to groundwater. This perpetuates differential ―degrees of access‖ to groundwater across the farming community and thereby creates conditions under which the poor farmers are left with the only choice of buying water from rich well owners. As the marginal cost of abstraction of water is zero, increased pumping to sell water or to irrigate his/her own field reduces the implicit cost of 30
irrigation water and provides greater opportunities to the well owners to maximise their economic returns. The price at which water is sold in the area is determined by the capacity of the pump used in terms of horsepower. Water from a tube well, which has a 30 HP submersible pump, is priced Rs. 30 per hour. As the capacity of the pump will have to be increased with increased depth of pumping, the hourly water charge is also bound to increase with increase in the depth to water levels. For example, in central Mehsana, where the depth to water level is around 450 feet, the hourly water charge ranges from Rs. 60 to Rs. 90. At the same time, in Daskroi taluka of Ahmedabad, where the depth to water level in tube wells is in the range of 250-270 feet, the hourly water charge ranges from Rs.20 to Rs.50. Therefore, in areas with deep water tables, water is likely to be costlier than in areas with comparatively shallow water table due to the reason that the increase in pump capacity may not result in a commensurate increase in the discharge. Thus, the actual volumetric cost of water is determined by the geo-hydrologic environment prevailing in the area. The increase in water cost essentially takes care of the higher initial investment for drilling tube wells and the higher cost of the pump. Figure 11 shows the unit price charged by a sample of 30 well-owning farmers in two
Figure 11: Groundwater Price vs Implicit Cost of Extraction in Ode and Jetpur Villages of Ahmedabad District 1.00 0.80 0.60 0.40 0.20 0.00
Unit Rate of Water
Amarsing
Karuji
Bachhu
Phoolji
Arvind
Gopal Rana
Naven
Daya Jiva
Mulu
Deelip Bala
Ramesh
Pravin
Ranjeet S
Delip
Implicit Cost of Water
villages, namely, Ode and Jetpur in Daskroi taluka of Ahmedabad district. The graph shows that the price at which many of the farmers sell water is much higher than the implicit cost of water. It is observed that the variation in the unit rate of water is just marginal, and almost all the well owners are charging an hourly price equal to the capacity of the pump they are using. The existing minor variation in prices across well owners is due to the difference in the depth to water level in the wells, which determines the variations in the discharge of wells. At the same time, major differences are found in the implicit cost of water depending on the acreage under irrigation and the hours of operation of tube wells to provide irrigation water to the neighbouring farmers. It ranges from the lowest of Rs. 0.13/m3 (or Rs.10.6 per hour) for a farmer, who runs his tube well for 3,000 hours a year, and as high as Rs.82/m3 (Rs.36 per hour) for a farmer who uses his well water for only 840 hours a year. Those farmers who are able to maximise the use of the pump can bring down the implicit cost of water significantly. At the same time, this does not seem to have any bearing on the price at which water is sold. For instance, the farmer who incurs the lowest implicit cost of Rs.0.13 per m3 of water charges Rs.0.38 per m3. Another farmer, whose cost is Rs. 0.18 per m3 charges Rs.0.49 per m3 of water. 31
On the other hand, the farmers who do not have sufficient land to irrigate, or who do not get enough buyers for their water, incur high implicit costs for the water they use. They are not able to increase the price of water due to the fear that they will lose the market. This means the price of water is determined by the supply-demand interactions in the market. But, irrespective of the implicit cost of water vis-à-vis the selling price, for a well owning farmer, selling water makes economic sense unless he/she has sufficient land of his/her own to irrigate. This is because of two reasons: (a) the amount of money collected from the sale of water is a net economic gain for the well owner; and (b) with increased hours of irrigation service, the implicit cost of using irrigation water for his/her own field reduces. This is due to the fact that there is no marginal cost of extraction of water. But, in comparison to a large farmer, who is selling water, a small farmer cannot earn as much from irrigation. This is not only because he generates much less income from sale of water, but also due to the higher cost (implicit) of the water used for irrigating his own fields. At the same time, a water buyer has to be content with lower returns from farming as compared to a well owner due to the following reasons: [a] the high water rate; and [b] the limited amount of water he can manage to buy from the well owners, unless he is uniquely placed to get as much water as he wants from the neighbouring well owner, or a number of well owners. In a nutshell, what emerges from these observations is that groundwater depletion and the consequent emergence of water markets provide greater opportunities for large well owning farmers to maximise their economic returns from a combination of irrigated farming and water selling. 5.2.2 Impact on Efficiency of Water Use Water markets seem to have a significant positive impact on the efficiency of use of water in irrigation. There are two major reasons for this. First: the farmers who buy water from private well owners pay for it on hourly basis. Thus, there is a positive marginal cost of the use of water for irrigation unlike in the case of well owners whose marginal cost of using electric power for groundwater abstraction is zero. This, as per the principle of equi-marginal returns, ensures economically efficient use of water. Second: the irrigation service provided is always limited due to the presence of a large number of potential buyers. Often the time elapsed between two waterings is too large to grow crops that require frequent waterings. It has been found that the farmers who irrigate their crops with purchased water tend to grow less water-intensive subsistence crops and try and optimise the number of waterings for the crops. This is, in most cases, at the cost of yield. Unlike the well owners, they grow water intensive crops on a very limited scale. While alfalfa—a highly water intensive crop-- is a favourite fodder crop of North Gujarat farmers, only very few farmers who depend on purchased water grow this crop. The main reason for this is the high cost of irrigation for growing alfalfa, which makes it a financially un-viable proposition. On an average, the farmers provide 24-30 waterings to alfalfa crop over the two seasons, namely, winter and summer, which cost Rs. 1200 to Rs. 1500 per bigha. An analysis of the data collected by us from well-owning farmers and water buyers shows significant differences in the pattern of irrigation between two categories of farmers. For winter wheat in Daskroi taluka of Ahmedabad, the average number of waterings in the case of wellowning farmers was 5.3 as against 4.7 in the case of water buyers. But, while water buyers seem to be applying less water as compared to well-owning farmers, they get slightly higher yield. The estimated yield rate was 3502 kg for water buyers against 3457 for well owners. For summer jowar in the same area, the average number of waterings in the case of well owning farmers was 6.8 against 5.3 in the case of water buyers. 32
According to Kumar (2000), allocation of limited water rights on volumetric basis encourages farmers to bring more area under low water consuming crops, which generate same economic returns per unit volume of water as compared to their counterparts who grow crops that are more water intensive. In the study, water use efficiencies of two major crops grown by the farmers who are members of a groundwater irrigation organisation were compared against the cropping pattern they adopt. In these irrigation organisations, the ―hours of irrigation per unit area of land‖ each farmer member was entitled was fixed and limited. The analysis showed that mustard and wheat yields the same economic return per unit volume of water used. Though wheat yielded higher return per unit area, area under mustard was two times the area under wheat. As amount of irrigation water was limited, farmers adjusted their cropping pattern in such a way that more area was allocated to low-water intensive mustard and avoided the risk of crop failure due to water shortage which otherwise would occur if the entire area is allocated to growing wheat. 5.3
Increased Dependence on Irrigation and Fertilisers
No. of Irri gations
In Sabarmati basin, soil degradation, which has taken place over a period of time due to breaking of soil structures, reduction in water retention capacity and loss of soil organic matter; and increase in soil salinity, has resulted in increased irrigation requirement for several winter and summer crops. Similarly, the fertiliser input requirement has also increased due to loss of organic matter content in the soils. In order to make good the losses from the declining primary productivity of soils caused by land degradation, farmers are forced to apply more water and fertilisers to their crops to sustain the production levels. Due to increase in soil salinity, the farmers have to apply extra water to flush out the salts in the soils. Often, extra water is needed to break the soil pan formed as a result of salinity. The deterioration of water retention capacity of the soil leads to higher percolation losses from irrigation, Figure 12: Historical Changes in Irrigation Rates, which further calls for increasing Daskroi, A'bad the frequency of irrigation. 16.00 Kharif Paddy The historical changes in Wheat 14.00 Alfalfa the irrigation water application 12.00 Fodder Jowar (Summer) 10.00 rates were studied by analysing 8.00 the variations in the number of 6.00 irrigations applied for the same 4.00 type of crop over a period of 30 2.00 years12. Here, one significant 0.00 assumption, which we make, is 1970 1975 1985 1990 1990 that the changes in the frequency of irrigation directly contributes to irrigation water application rates, and any reduction in the discharge of wells is adjusted through increasing or decreasing hours of water delivery per watering. For this, primary data collected from the field on the number of waterings from a sample of 25 farmers in Daskroi taluka of Ahmedabad district were analysed and are presented here. The analysis shows that the number of waterings applied to all the four major crops grown in the region has increased consistently over the period, 1970-2000. For instance, the average number of waterings for paddy (kharif) had gone up steadily from 2.5 in 1970 to nearly 3.5 in 12
The historical changes in fertiliser application rates have already been discussed in the earlier section on ecological consequences and hence are not covered here.
33
No. of Irrigations
1985 to 5.5 in 2000. This is a major difference. Similar differences were found in the case of wheat and summer jowar (fodder) also. The average number of waterings for jowar had gone up steadily from 3.3 in 1970 to 4.75 in 1985 to 6.2 in 2000. For wheat, the increase in the number of waterings was only one over a period of 30 years. But in view of the fact that the irrigation water requirement for the crop had actually reduced following the introduction of hybrid variety of the crop due to the reduced time required for crop maturity (with a saving in one watering), the actual increase in the numbers of waterings for the crop is almost two. Similarly, for alfalfa, the number of watering has significantly increased from 9.5 in 1970 to 13.4 in 1985 to 14 in 2000. A similar trend was found in Kalol taluka of erstwhile Mehsana district. The farmers there have been growing paddy and Figure 13: Historical Change in Irrigation for cotton in Kharif, wheat in Different Crops, Kadi, Mehsana winter and bajra in summer. 12 Water Use in Kharif Paddy Here the highest increase in Water Use in Cotton 10 water application rate was Water Use in Wheat found in the case of Kharif 8 Water Use in Bajra paddy where the average 6 number of waterings for the 4 crop increased consistently 2 from 3.5 to 9.6. In the case of wheat, the number of waterings 0 1970 1975 1985 1990 2000 increased from 4.3 to approximately seven. In the case of bajra, the increase was from 4.2 to seven (Figure 13). Though a significant increase in the number of waterings was found in the case of cotton, most of it can be attributed to the shift from the low water consuming indigenous variety to the comparatively high water consuming hybrid variety. Whereas change in variety had also taken place in the case of other crops, especially wheat, the new hybrid varieties are less water consuming than their traditional counterparts. The increase in frequency of irrigation can, therefore, be directly attributed to the changes in soil conditions occurring as a result of breaking of soil structures, reduction in water retention capacity and loss of soil organic matter, and increase in soil salinity and the additional water the farmers have to use in conjunction with fertilisers. 5.4
Health Impacts of Groundwater Quality Deterioration
The rising level of fluoride content in pumped groundwater is one of the most alarming trends observed in many parts of Gujarat. This is posing a serious threat to drinking water supplies and human and animal health in the State. A large percentage of the fluoride-affected area in Gujarat is in Sabarmati basin. According to GOG (1996), there are 532 villages affected by fluorides in the basin out of a total of 2800 villages in the state facing the problems of high fluoride in groundwater. High levels of fluoride are mostly found in the deep confined aquifers of the alluvial parts of the basin. Over the years, the degree and extent of fluoride contamination have been increasing and so also the number of villages affected. An analysis of chemical quality of groundwater in Shihori well field of Santalpur Regional Water Supply Scheme of Banaskantha showed a marked increase in fluoride levels in pumped groundwater from deep confined aquifers over a period of 6 years from 1.1-1.2 ppm in May 1988 to 1.5 to 2 ppm May 1994. The static water levels in all the wells dropped continuously at rate of 3-6 metres per year (Wijdemans 1995). There are enough empirical evidences to suggest that mineralisation of groundwater, and consequent increase in 34
fluoride levels are associated with excessive pumping which causes reduction in the aquifer pressure and activates geo-hydro-chemical processes. Therefore, in North Gujarat, excessive fluoride in pumped groundwater is directly associated with aquifer over-exploitation and mining. Due to absence of any surface water based water supply schemes, the rural people in the region are fully dependent on groundwater supplies for drinking purpose. The de-centralised rural drinking water supply schemes are wholly based on groundwater supplies. While the schemes tap fluoride free groundwater in the initial stage of their operation, over a period of time, fluorides start building up due to geo-hydrochemical processes taking place in the underground formations. The Water Supply and Sewerage Board (GWSSB) does not have any system for regular monitoring and analysis of the chemical quality of the water being supplied for drinking in the rural areas. The de-centralised schemes, which directly put the water into the distribution system, lack water treatment facilities. In addition to the de-centralised public schemes, the rural communities also use water from their own private wells meant for irrigation purpose for drinking and domestic purposes also. The problem of fluoride in drinking water is not limited to rural areas alone. TDS in Ahmedabad are frequently beyond permissible levels and widespread occurrence of fluoride has been reported from many pumping stations of Ahmedabad Municipal Corporation (AMC). According to newspaper reports, water from AMC tube wells has fluoride levels as high as 6 ppm against the permissible level of 1.5 ppm. Unlike TDS, salinity and alkalinity, the presence of which can be detected or traced by ―tasting‖, fluoride presence in water cannot be detected without the help of water quality testing equipment. The presence of high fluoride levels in groundwater is often detected from its manifestations in such symptoms as yellowing of teeth, and joint pain, which occur from long years of exposure to fluoride containing water. Due to these reasons, the communities in the region have been exposed to drinking water containing high levels of fluoride for a long period of time without being much aware of it. By the time the communities realised the ―menace‖ and its long-term effects13 on health, a large section of the population had already been affected. The biological and toxicological effects associated with the use of water containing fluoride for drinking and cooking are yet to be fully explored. But if the available scientific knowledge is any indication, the potential effects are dangerous. Studies on fluorotic human populations of North Gujarat carried by Sheth FJ, Multani AS and Chinoy NJ (1994) revealed an increase in frequency of sister chromatic exchange in fluorotic individuals as compared to the control indicating that fluoride might have genotoxic effect. Fluoride had been reported to cause depressions in DNA and RNA synthesis in cultured cells (Strochkova et al. 1984). A study by Patel and Chinoy to evaluate the effects of fluorides on nucleic acid and protein levels in the ovary and the fertility impairment in mice under experimental fluorosis showed significant reductions in DNA and RNA levels (Patel and Chinoy 1998). Inhibition of DNA and RNA synthesis may result in delayed mitotic and meiotic cycles including chromosomal breakage (Vorishilin et al. 1973). Several human conditions including ageing, cancer, and arteriosclerosis have been associated with DNA damage and its disrepair. Like fluoride, nitrates and TDS are also sources of many health problems in the basin area. According to GOG (1996), there are 216 salinity-affected and 173 nitrate affected villages in the basin.
13
Some of the long-term effects on human body are crippling effect, and hunchback.
35
6.0
CONCLUSIONS AND POLICY IMPLICATIONS
Groundwater over-exploitation is a complex phenomenon to study due to the complex nature of groundwater system behaviour, the lack of a universally accepted methodology for estimation of groundwater recharge, and the economic, social, and ethical considerations involved in assessing over-development. A realistic assessment of groundwater over-development needs a multi-disciplinary study and analysis of the situation including evaluation of hydrology, study of hydro-dynamics in different aquifers, analysis of real costs and benefits of groundwater abstraction including the environmental costs and benefits, ethical considerations involved in the use of water and assessing the socio-economic and ecological consequences of over-development. This study employed a multi-disciplinary approach to explore various dimensions of ground-water exploitation in the Sabarmati river basin in Gujarat. The study revealed several symptoms of an impending groundwater crisis in the basin. They included declining groundwater levels; poor economics of groundwater irrigation; unethical water use practices; drinking water scarcity in hard rock areas; and ecological problems such as land degradation due to [i] waterlogging and salinity, [ii] breaking of soil structure, water retention capacity and loss of organic matter and nutrients, and [iii] increase in soil salinity; and reduced feasibility of growing vegetables using deep aquifer water. Over-exploitation of groundwater was found to have several socio-economic and ecological consequences. Most important of them are: emergence of water markets, which perpetuate access inequity in groundwater use for irrigation in favour of the rich and large farmers; increased dependence of farmers on irrigation water; and increasing levels of fluoride in groundwater, which pose serious threats to human biological and physiological health. The interventions required to reverse the imbalances in groundwater ecosystem in the ecologically fragile Sabarmati basin involve huge investments for creating management institutions in the critical areas as well as for carrying out physical activities for restoring the degrading systems. Water development decisions in the State and elsewhere in the country are primarily guided by economic objectives and criteria, which promote only those investments that are capable of giving higher direct economic returns in the water sector. The study revealed that the social, economic, ecological and environmental costs associated with groundwater degradation—which is the result of lack of proper institutional regimes to govern the use of groundwater--are huge and should not be over-looked. As a result, the investment decisions for groundwater management projects should be based on all economic, environmental, ecological, and social considerations. This would enable the policy makers consider the positive environmental, ecological and social effects as the project benefits, which otherwise would continue to be lost sight of. To conclude, groundwater management policies for ecologically fragile regions should be guided by the principles of sustainability, equity, ecology and environment rather than just economic criteria. REFERENCES Bruntland, G. M. et al. (1987) ―Our Common Future,‖ World Commission on Environment and Development, Oxford University Press. Custodio, E. (1992) Hydrological and Hydrochemical Aspects of Aquifer Overexploitation. Selected Papers on Aquifer Overexploitation. Intern. Assoc. of Hydrogeologists, Heise, Hannover, 3: 3-28.
36
Custodio, E. (2000) The Complex Concept of Over-exploited Aquifer, Secunda Edicion, Uso Intensivo de Las Agua Subterráneas, Madrid. Custodio, E. and A. Gurguí (1989) Groundwater Economics. Elsevier. Amsterdam. Custodio, E. and M. R. Llamas (1997) Consideraciones sobre la génesis y evoluión de ciertos ―hidromitos‖ en España. En Defensa de la Libertad: Homenaje a Victor Mendoza. Instituto de Estudios Económicos, Madrid: 167-179. Delgado, S. (1992) Sobreexplotación de acuíferos: una aproximación conceptual. Hidrogeología y Recursos Hidráulicos. Asoc. Española de Hidrología Subterránea. 25: 469-476. Georgescu-Reogen, N. (1971) The Entropy Law and the Economic Process. Harvard University Press, Cambridge. Government of Gujarat (1994) ―Integrated Plan of Sabarmati River Basin,‖ Draft Report, Gujarat State Water Resources Planning Group,‖ Gandhinagar, Gujarat, India. Hardin, Garrett (1968), ―The Tragedy of the Commons‖, Science, 162:1243-48. Howitt, R. E. (1993) ―Resolving Conflicting Water Demands: A Market Approach. The Water Economy‖. Soc. General de Aguas de Barcelona. Barcelona: 151-164. IRMA/UNICEF (2001) White Paper on Water for Gujarat, Institute of Rural Management, Anand. ITGE (1991) Sobreexplotación de acuíferos: Análisis Conceptual. Instituto Techológico Geominero de España, Madrid. Kumar, M. D. Shashikant Chopde, Srinivas Mudrakartha and Anjal Prakash (1999) ―Addressing Water Scarcity: Local Strategies for Water Supply and Conservation Management in Sabarmati River Basin,‖ M. Moench, E. Caspari and A. Dixit (eds.) Rethinking the Mosaic: Investigations into Local Water Management. Kathmandu, Nepal Water Conservation Foundation and Institute for Social and Environmental Transition. Kumar, M. D. (2000) ―Institutions for Efficient and Equitable Use of Groundwater: Irrigation Management Institutions and Water Markets in Gujarat, Western India,‖ Asia-Pacific Journal of Rural Development. X (1). Llamas, M. Ramon (1992a) La sobreexploitatión de aguas subterráneas bendición, maldición on entelequío?. Tecnologia del aqua Barcelona. 91:54-68. Llamas, M. Ramon (1992b) La surexploitatión des aquiféres: Aspects Techniques et Institutionnels. Hydrogéologie, Orleans. 4: 139-144. Llamas, M. R. and Priscoli, J. D. (2000) ―Report of the UNESCO Working Group on Ethics of Freshwater Use,‖ Water and Ethics, Special Issue. Papeles del Proyecto Aguas Subterraneas, Uso Intensivo de Las Agua Subterraneas, Madrid. 37
Margrat, J. (1993) The Overexploitation of Aquifers. Selected Papers on Aquifer Overexploitation. Intern. Assoc. of Hydro-geologists. Heise. Hannover. 3: 29-40. Moench, M. (1995) When Good Water Becomes Scarce: Objectives and Criteria For Assessing Over-development in Groundwater Resources, M. Moench (ed) Groundwater Availability and Pollution: The Growing Debate over Resource Condition in India, Ahmedabad, VIKSAT. ORG (2000) State Environmental Action Plan, Draft Report on Hydrologic Regimes SubComponent, Submitted to Gujarat Ecology Commission, Government of Gujarat, Vadodara. Patel, D. and N. J. Chinoy (1998) ―Ameliorative Role of Amino Acids on Fluoride-Induced Alterations in Mice (Part II): Ovarian and Uterine Nucleic Acid Metabolism‖, Fluoride. 31 (3): 143-148. Saleth, R. Maria (1994) ―Water Markets in India: A Legal and Institutional Perspective‖, Indian Economic Review, 29 (July-December): 157-76. Sheth F.J., A. S. Multhani and N. J. Chinoy (1994) ―Sister Chromatic Exchange: A Study of Fluorotic Individuals of North Gujarat,‖ Fluorosis. 27 (4) 215-219. Singh Katar (1995), ―Cooperative Property Rights as an Instrument of Managing Groundwater‖ in Marcus Moench (Ed.), Groundwater Law: The Growing Debate, VIKSAT-Pacific Institute Collaborative Groundwater Project, Ahmedabad, pp. 70-72. Singh Y. D. et al. (2000) State Environmental Action Plan Phase-1 Report on Ranns and Desertification, submitted to Gujarat Ecology Commission, Government of Gujarat, Vadodara. Strochkova et al. (1984) ―Effects of Fluoride on Morphological Modifications in Hela Cell Culture‖, Tsitologiya.26: 299-206. Vorishilin SI, E. G. Plotko, E. Z. Gatiyatulline, E. A. Gileva (1973) ―Cytogenetic Effect of Inorganic Fluorine Compounds on Human and Animal Cells in vivo and in vitro,” Genetica. 9 (422). Young (1992) Managing Aquifer Over-exploitation: Economics and Policies. Selected papers on Aquifer Over-exploitation, International Association of Hydro-geologists, Heise, Hannover.3: 199-222. Wijdemans, R. T. J. (1995) ―Sustainability of Groundwater for Water Supply: Competition between the Needs for Agriculture and Drinking Water,‖ M. Moench (ed.) Groundwater Availability and Pollution: The Growing Debate over Resource Condition in India, Ahmedabad, VIKSAT.
38
