| |
Rapid increase in groundwater use is causing groundwater depletion and water scarcity in many parts of the world. This study evaluates whether the semi-arid southern India is also experiencing significant decline by analyzing the long term (1990-2012) groundwater levels for three districts (administrative division in a state) with diverse land uses. We also use a modeling (MIKE SHE/MIKE11) approach to evaluate potential management solutions. Non-parametric trend test results showed statistically significant (p < 0.05) declines in 22% to 36% of the wells. This is contrary to commonly held view of widespread groundwater decline. Trend tests for rainfall and rainfall adjusted groundwater levels (locally weighted regression residuals) showed that rainfall variability could not fully explain the declining trends. Increase in numbers of irrigation wells and irrigated area combined with the free electricity policy for farmers, implemented in 2004, were the main causative factors. Up to 76% of these wells also showed a statistically significant step-up trend in groundwater levels during the post-subsidy (2005-2012) period, confirming the nexus between power subsidy and groundwater. Continued increase in groundwater-based irrigated areas is likely to increase the groundwater level declines and well drying occurrences in the future. The MIKE SHE/MIKE 11 modeling for a watershed (Kotahpally, 320 ha) in the region showed that a combination of demand and supply management strategies such as runoff water retention through check dams, conversion from flood to drip irrigation, reduced power subsidy and regulated pumping could help maintaining or improving the groundwater levels thereby increasing the water availability in the region. Weathered fractured aquifers, similar to those in this study, cover about two-third of India (240 million ha) and their appropriate management is critical to maintain or enhance the agricultural production and provide adequate water supply to urban and industrial sectors under the current and future climatic conditions. |