Tracing the process of precipitation cycle in the headwater area of Qinghai-Tibet Plateau

Studying the precipitation cycle process in the headwater area is of great significance to its water resource protection and management, using the raindrop evaporation and water vapor recirculation model to quantify the proportion of each link of precipitation cycle process and discuss the differences and influencing factors of the proportions of the precipitation cycle process in May to September in 2019 and 2020. The results showed that the average proportions of external precipitation sources ( f w ) from May to September in 2019 and 2020 were 77.55% and 76.51%, respectively; the average remaining ratio of raindrop evaporation ( f r ) was 79.41% and 78.11%, respectively; the average evaporation ratio of raindrop ( f e ) was 20.59% and 21.89%, respectively; the average local circulating water vapor proportion ( f a ) and precipitation ( P ) were 22.45%, 23.49%, 95.17 mm, and 98.59 mm, respectively. In terms of the influencing factors of the various proportions of the precipitation cycle process in the headwater area, f w and f a were mainly affected by temperature; f r and f e were mainly affected by relative humidity, and P was mainly affected by total precipitation. The research results can provide theoretical basis and data support for the effective use of water resources in the headwater area of the Qinghai-Tibet Plateau.