Groundwater is a critical resource for food security, providing 40% of the world’s irrigation . Millions of farmers depend on groundwater irrigation to help produce 40% of the world’s agricultural production, including a large proportion of staple crops like rice and wheat . Yet, groundwater reserves are becoming rapidly depleted in many important agricultural regions across the globe . While the extent of current and projected groundwater depletion is well documented , the potential impact of this depletion on food production remains poorly quantified. Furthermore, it is unclear whether there are any adaptation strategies that may reduce the projected negative impacts of groundwater depletion on agricultural production. Yet, such information could help identify which adaptation strategies should be prioritized in which regions to ameliorate and avoid large production losses in the areas most at risk for groundwater depletion.
It is especially critical to quantify the impacts of groundwater depletion on crop production in India—the world’s largest consumer of groundwater—where groundwater provides 60% of the nation’s irrigation supply. Tube well construction has rapidly increased since the 1960s across India, allowing farmers to increase cropping intensity, or the number of seasons when crops are planted in a given year, by expanding production into the largely dry winter and summer seasons . This increase in cropping intensity is credited for much of the food production gains achieved over the past 50 years across India. However, because of high rates of extraction, aquifers are rapidly becoming depleted across much of India, with the northwest and south predicted to have critically low groundwater availability by 2025 This is of concern given that India produces 10% of global agricultural production and is the second largest producer of wheat and rice. Furthermore, a majority of India’s rural population, approximately 8% of the world’s population, depends on agriculture as a primary livelihood, and a reduction in agricultural production will negatively affect household welfare .
Very few studies have attempted to quantify the potential impacts of groundwater depletion on agricultural production in India. To date, efforts have largely relied on modeling approaches , which necessarily make assumptions about the relationship between groundwater use and crop productivity. With such an approach, it is difficult to account for real-world constraints that may reduce the efficiency of groundwater use, such as inefficient pumps and the inability of some farmers to irrigate at full capacity. Accounting for these limitations is particularly critical in regions like India, where water use efficiency is low and extremely heterogeneous across the country . Only one previous study has incorporated empirical data on the relationship between irrigation use, crop production, and groundwater depletion. However, because of data limitations, this study relied on coarse district-level agricultural census statistics that do not distinguish between whether a crop is irrigated by groundwater or other sources, like canals. Thus, to date, it has not been possible to empirically estimate the association between groundwater use, crop production, and groundwater depletion, which is critical for accurately estimating the potential production losses that may occur when overexploited groundwater is lost.