Spatiotemporal variations in surface water and its significance to desertification in China from 2000 to 2019

Dynamics in surface water area (SWA) and its impacts on desertification are poorly understood in the desertification-prone region (DPR) of China. We defined 2440 sub-watersheds at the fifth-order level in China's DPR, and investigated the spatiotemporal variations in SWA and their substantial driving factors (such as temperature, precipitation, evaporation, and irrigation activity). The results showed that the average annual maximum SWA was 7165 km2 in DPR from 2000 to 2019, of which 84% was the seasonal SWA. The seasonal and permanent SWA increased by 188 km2 yr−1 and 46 km2 yr−1, respectively. The SWA in non-DPR was the dominant driving factor for SWA dynamics in most basins except for HunlunBuir, Otindag and Ordos, where the irrigation activity showed significant contributions to SWA variations. Climate had a relatively low contribution to SWA variations in DPR. The role of SWA variations on desertification processes in DPR of China showed significant spatiotemporal differences from 2000 to 2019. The increased SWA promoted reversal of desertification in watersheds along the Tarim River, northwestern Junggar, eastern Ordos, and parts of Otindag, however, it did not help in northwestern Qinghai. Our findings provide a scientific insight into the characteristics of surface water resources and the relationship between SWA dynamics and desertification in the DPR of China.