A hotspot analysis of water footprints and groundwater decline in the High Plains aquifer region, USA

Severe groundwater depletion of the High Plains aquifer (HPA) demands sustainable utilization of water resources to ensure continued freshwater supply in the region. Considering the period 1990–2012, the region’s average water footprint (WFarea) of the major irrigated crops alfalfa, corn, cotton, sorghum, soybean and wheat has been determined as 45.72 km3 year−1 (54 % blue, 46 % green). Clustering the HPA by groundwater decline, blue WFarea and green WFarea allowed for spatial differentiation of hotspots. We show that two clusters, classified as “significant” and “severe,” cover 20 % of the irrigated land, yet consume 32 % (7.94 km3 year−1) of the total blue WFarea. WFcrop (blue and green water consumption per unit yield) is highest in the cluster “severe,” paired with the largest fraction of blue water consumption (66 %). In contrast, green water satisfies crop water demands in the northern subregion, where the lowest WFcrop and the largest fraction of green water consumption occur (67 %).