Evaluation of the Evapotranspiration in the West Liaohe River Basin Based on GRACE Satellite and in Situ Measurements

The West Liaohe River Basin (WLRB) is one of the most sensitive areas to climate change in China. Here we use the terrestrial water fluxes derived from the Gravity Recovery and Climate Experiment (GRACE) satellites, precipitation dataset, and in situ runoff records, to calculate the actual evapotranspiration (ET) in the WLRB based on the water balance equation. We find that during the drought period of 2005-2011, the mean annual ET is 350.5 mm, which is 9.8 mm more than the mean annual precipitation during the same time period. This difference can be explained by the groundwater depletion in the WLRB (about 6.8 mm/a). We also find that the ET products from remote sensing both underestimate the actual ET in the WLRB, compared with the GRACE-based ET results. However, the ET simulated by the global land data assimilation system version 2.1 (GLDAS-2.1) Noah is overestimated. This paper highlights the capability of GRACE to monitor actual ET in the WLRB and to validate different ET products from remote sensing and models.