Irrigated crop migration severely accelerated global groundwater depletion

Abstract

As the primary global freshwater consumer, the migration of irrigated agriculture plays a critical role in driving alarming groundwater depletion and hence threatens sustainable water management and food security. Yet, little is known regarding the dynamic changes of historical irrigated agriculture migration, and therein the associated threatening impacts on groundwater depletion. Here, we couple a state-of-art global crop water model, global hydrological models, and long time-series of statistic data to provide one of the first attempts to map the spatial-temporal heterogeneities in irrigated agriculture migration patterns across the globe during the past thirty-five years (1985-2019), and unravel the dynamic impacts of irrigation migration on groundwater depletion across global key food-producing regions. We find that a global average 6.29 degree eastward crop migration results in 37% increases in global groundwater depletion intensity and 46% of global total groundwater depletion increases (68.5 km3) over this period, particularly across global major breadbaskets such as India, China, which together contribute 83%, 83% and 87% of global food crop, fruit and vegetable production. Generally, crop migration significantly exacerbates groundwater depletion intensity in developing Asia (particularly reverses the otherwise decreasing trend in India and Pakistan), while alleviating groundwater depletion in developed North America and Europe. Our study highlights the previously overlooked unsustainable crop migration trend in severely accelerating groundwater depletion over the past four decades and calls for cautious irrigation migration planning, particularly across global breadbaskets.