Spatiotemporal Patterns of Hydrological Variables in Water-Resource Regions of China

The spatiotemporal patterns of key hydrological variables across China were illustrated based on the developed Water and Energy Transfer Processes model in China (WEP-CN model). Time series of four key hydrological variables, namely, precipitation (P), runoff (R), infiltration (Inf), and actual evapotranspiration (ETa), were obtained over 60 years. Then, the temporal trends and spatial differences of these variables were analyzed using the Mann-Kendall and linear methods on a national scale and on the water resource regional scale. Moreover, we explored the drivers and constraints for changes in R, Inf, and ETa. The results showed: (1) Based on the coefficient of variations of P (5.24%), R (11.80%), Inf (2.57%), and ETa (3.77%), R was more fluctuating than the other variables. (2) These variables followed a similar trend of gradually decreasing from the southeast coast to the northwest inland. (3) Changes in R and Inf were caused mainly by P, having correlation coefficients with precipitation of 0.74 and 0.73, respectively. The ETa was constrained by a combination of P and energy. The results improved the refined and quantitative research on hydrological processes in China, identified the differences in hydrological variables between water-resource regions, and provided a useful supplement to the research of the large-scale hydrological process.