Modeling the Impacts of Soil, Vegetation and Climate on Evapotranspiration and Groundwater Recharge during 2001-2010 on the Chinese Loess Plateau

English Abstract:

Knowledge of spatio-temporal soil water balance over the Chinese Loess Plateau (CLP) is crucial to optimizing land uses for sustainable development. Daily evapotranspiration (ET) and groundwater recharge (GR) at 58 sites on the CLP during 1981-2010 was simulated using the HYDRUS-1D model. The impacts of soil, climate, and vegetation on annual ET and GR during 2001-2010 were explored. Both the annual ET and GR generally decreased from the southeast to the northwest, with annual ET ranging from 14.3 cm (105% of precipitation (P) ) to 59.5 cm (82% of P) and annual GR from 0.0 cm to 14.3 cm (18% of P), respectively. The average simulated annual ET and GR were 39.0 cm and 2.4 cm over the CLP, contributing to 95.6% and 4.7% of annual P, respectively. Annual evaporation (E) was twice greater than annual transpiration (T) due to the sparse vegetation in most areas of the CLP. Spatial distribution of ET was dominated by P followed by leaf area index (LAI) and potential evapotranspiration (ETp). Specifically, LAI played an equivalent control on T as P did. Groundwater recharge was also dominated by P, while it was not affected by the ETp and LAI at the region scale. Soil hydraulic properties also influenced the distribution of ET and GR, but their effects were much smaller compared to the climatic forcings. This work highlights the dominance of P on water flux at the regional scale on the CLP, providing a basis for eco-restoration and groundwater use scheduling.