How serious are groundwater over-exploitation problems in India?: a fresh investigation into an old issue

In this paper, first we deal with the definition of aquifer over exploitation. Then a review of the various definitions and criteria for assessing over exploitation is provided. Subsequently, the existing methodologies in India for assessment of groundwater resources are reviewed to examine: the robustness of the criteria used; and the scientific accuracy of the methodologies and procedures suggested. Finally, the current estimates of groundwater over development for India are reviewed from the perspective of detailed water balance, geology, hydrodynamics, and negative social, economic, ecological and ethical consequences. The paper argues that there are several conceptual issues involved in the assessment of aquifer over exploitation. Over-exploitation is linked to various “undesirable consequences” of groundwater use that are physical, social, economic, ecological, environmental, and ethical in nature. Further, there are differences in the way undesirable consequences are perceived by different stakeholders. The principle of inter-generational equity used in the concept of sustainability, is built in the standard definitions of aquifer over exploitation. But, defining and assessing over exploitation is both difficult and complex, and not amenable to simple formulations. The criteria used for assessing groundwater development by groundwater estimation committee (GEC) 1984 are only physical, involving variables such as gross groundwater recharge and net abstraction. The criterion adopted by GEC-97 is more rigorous. It involves net groundwater recharge and gross draft. It takes into account some of the complex variables determining net recharge, such as base flow and lateral flows. But, both fail to integrate complex hydrological, geological, hydro-dynamic, social, economic and ethical factors that capture the physical, social, and economic impacts of groundwater overuse. This apart, there are issues of reliability in estimation of net groundwater recharge and draft, due to lack of robustness in the methodologies, owing to the absence of reliable data required for estimation. The official statistics therefore provide a not-so-bad scenario of groundwater in the country. The paper demonstrates through selected illustrative cases how integrating data on complex hydrology, geology, hydro-dynamics, and socio-economic, ecological and ethical aspects of groundwater use, with the official statistics could change India’s groundwater scenario altogether. Some of them are: break up of groundwater balance into natural recharge, recharge from imported water, and consumptive water use; specific yield of aquifer; long term and seasonal trends in groundwater levels; economic cost of groundwater abstraction; incidence of well failures and change in well yields; and drinking water scarcity