Impact of groundwater overextraction and agricultural irrigation on hydrological processes in an inland arid basin

Irrigation accounts for a major proportion of human water usage, exerting significant impacts on the natural environment and regional climate in inland arid basins. Groundwater overextraction and agricultural irrigation can drastically alter the water distribution in terrestrial systems, with potential impacts on hydrological processes. To better understand these risks and improve water resource regulation in inland arid basins, a land surface model was employed to investigate the impact of different groundwater overextraction ratios and irrigation efficiencies on hydrological processes in the Heihe River Basin during 2015-2020. The model integrated daily irrigation water use data that were estimated through the combination of satellite data and machine learning. The results showed a rationality of irrigation water use data between the inter-annual variation of estimated irrigation data and government reported data. When irrigation water was only withdrawn from the surface, it effectively increased evapotranspiration and soil moisture, with little impact on water table depth. However, the groundwater balance was seriously impaired when groundwater was extracted for irrigation, increasing water table depth (32.6%) and depleting groundwater storage throughout the study period.