Examining moisture contribution for precipitation in response to climate change and anthropogenic factors in Hengduan Mountain Region, China

Climate change and anthropogenic factors have resulted in intense and frequent droughts and floods in the Hengduan Mountain Region (HMR). Exploring the source supply of evaporation and transportation processes for the precipitation in the HMR can help us understand regional precipitation characteristics and provide valuable insights regarding effective water resource management, disaster prevention, and mitigation. Based on the ERA5 reanalysis data, we identified the annual and seasonal precipitationsheds of the HMR, using the Water Accounting Model-2layer, to investigate the potential mechanisms that drive the changes in the precipitation in the HMR, in terms of external moisture contribution and local recycling. The identified precipitationshed in the HMR varied in response to different types of precipitation during the different seasons. The decrease in the annual precipitation was mainly attributed to the reduced moisture supply from the extended southwest (SW) and northwest (NW) regions, portraying a decreasing trend of -2.08 mm/yr/yr and -0.92 mm/yr/yr, respectively. The detected difference in the moisture sources and transport pathways, in terms of the response of wet and dry precipitation years, can improve our understanding of the moisture patterns of wet and dry years. We could conclude that the increase in moisture from the SW regions, due to El Nin similar to o, may have triggered the heavy precipitation in the HMR in 1998. Additionally, the reduction in moisture from the SW regions, due to La Nin similar to a, may have triggered an extreme drought in the HMR in 2011. Notably, woodland and water surface expansion tend to weaken local recycling (-0.07 %/yr) after 2000. In the future, the decreasing trend of local recycling will likely be intensified owing to large-scale artificial reservoir construction and the surface changes caused by underlying impoundment.