Authors: A. Patrick Behrer, Hemant Pullabhotla
Declining groundwater levels are threatening the viability of irrigated agriculture in India with most (65 percent) of the agricultural production occurring in states that are currently experiencing groundwater stress. The Indian government has a number of policies and programmes in place to manage and mitigate groundwater withdrawals for irrigation such as the Atal Bhujal Yojana and the Mahatma Gandhi National Rural Employment Guarantee Act of 2005 (MNREGA).
MNREGA is focused on rural employment generation to reduce poverty and rural unemployment, with a secondary goal of increasing rural infrastructure to enhance rural productivity. These infrastructure projects focus on creation of durable public works projects that improve irrigation and water conservation and aid in drought proofing of communities.
Studies have found that MNREGA has led to increases in both local wages and employment, may have reduced migration and improved health outcomes for rural residents, but reduced educational attainment for some students.
Implementation of projects at a state and local level have led to large differences in the quality of outcomes across states with all the wage and employment impacts of MNREGA being concentrated in Andhra Pradesh, Chhattisgarh, Himachal Pradesh, Madhya Pradesh, Rajasthan, Tamil Nadu, and Uttarakhand.
However, no study has measured the return on investment in asset creation or the quality of the assets created by MNREGA. This recent Policy Research Working Paper by the World Bank titled 'Spilling over: The benefits of public works projects for groundwater in India' authored by A. Patrick Behrer and Hemant Pullabhotla examines the impact of MNREGA implementation on groundwater levels throughout India.
The study analyses data from more than 20,000 test wells that measured groundwater levels throughout India at multiple times each year from the late 1990s to 2012.
Aquifers in India
Most of the aquifers in India’s bread basket in the northwest and across the Indo-Gangetic plains have high rates of recharge and aquifers in the region display a high degree of surface connectivity. Agriculture here accounts for as high as 95 percent of the annual withdrawals from renewable groundwater resources.
At the other end are “fossil” aquifers that have no connectivity to the surface and were formed when water was trapped in a geological layer during past geological activity. Aquifers with high surface connectivity can be recharged by capturing and pooling water on the surface and allowing it to percolate into the aquifer.
Construction of check dams, soft-bottomed irrigation canals and water tanks are constructed under the MNREGA scheme that can increase aquifer recharge by allowing surface water to pool and then percolate through the soil into the aquifer.
The study finds that:
MNREGA implementation helps raise groundwater levels immediately following the monsoon season and through the dry planting season. This is consistent with MNREGA projects improving recharge rates and allowing for more monsoon precipitation to reach and be stored in groundwater reservoirs.
There is a significant increase in the soil moisture level after the implementation of MNREGA. This effect is concentrated during the rabi (dry) season when soil moisture is most determined by irrigation levels. The increase in soil moisture is consistent with the increase in the area irrigated across a range of crops after the implementation of MNREGA.
Farmers increase the share of crop area irrigated by approximately 15 percent for rice, wheat after the implementation of MNREGA. Farmers increase the area irrigated in fruits and vegetables by an even larger 34 percent.
Thus, MNREGA eases access to reliable groundwater and farmers, who were previously constrained by access to groundwater, and respond by irrigating more of their cropped area. Majority of irrigated land prior to the implementation of MNREGA was irrigated with water from wells.
The area irrigated by wells increases significantly after the implementation of MNREGA as compared to area irrigated by canals, tanks, or “other sources” of irrigation water.
Aggregate water use in irrigation is higher during the rabi season after MNREGA than prior to MNREGA.
Farmers substantially increase their irrigation of high value, water intensive crops after the implementation of MNREGA. The study finds that MNREGA has succeeded in improving the water conservation and irrigation infrastructure in states in which it was well-implemented. These improvements lead to higher groundwater recharge rates that, in turn, make irrigation water more available for farmers during the dry season and this leads farmers to increase irrigated areas and shift into higher value and water intensive crops thus increasing income and profits for some farmers.
Thus while MGNREGA leads to high groundwater recharge rates, making more water available for farmers during the dry season, this may not help in conserving groundwater as farmers increase area under irrigation to grow more water intensive crops.