Hydrological drivers of groundwater recharge changes under different emission scenarios in agricultural lands

Abstract. Groundwater is a crucial resource that helps ensure the security of food and water. Although the earth's water resources are being negatively impacted by climate change in every manner, there is still limited research on predicting future groundwater recharge. This study constructed the Soil and Water Assessment Tool (SWAT) under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) in conjunction with two General Circulation Models (GCMs) from Coupled Model Intercomparison Project 6 (CMIP6) to predict the change in agriculture groundwater recharge in 2021–2045 relative to the baseline historical data. The Yang River Basin in Hebei Province, China, which is mainly covered by agricultural land along the basin, as the study area to understand how climate change drives groundwater recharge in agricultural land. The results show that the model performs well, with Nash-Sutcliffe Efficiency (NSE) of 0.82 and 0.76 in the validation and calibration periods, respectively. The expected temperature and precipitation have increased more, 16.1 %–31.3 % and 1.8 °C–2.5 °C, respectively, compared with the historical period 1981–2005.While evapotranspiration (ET) has increased, the distribution of agricultural groundwater recharge reflected spatially varying characteristics, with an overall increasing trend of 31.3 % (2021–2045). Consequently, the study area was divided into five regions with varying degrees of wetness and dryness based on the spatial distribution of precipitation (P). It was found that in the higher–precipitation regions, runoff contributed a portion of the future net atmospheric input (P-ET), and it was further concluded that precipitation was the primary climatic factor that drove the recharge to farmland, while evapotranspiration also had an impact on the change in recharge for the relatively dry regions. This will help the region achieve sustainable development and get ready for climate change in the future. It will also provide local policy makers with some knowledge.