Attribution Analysis of Runoff in the Upper Reaches of Jinsha River, China

The upper Jinsha River is an important ecological reserve and hydropower energy base in China. This paper uses relative importance analysis to analyze the causes of runoff changes from the perspectives of early runoff, rainfall, snowfall, evaporation and soil water content. The results show that the factors influencing runoff in the upper Jinsha River are complex and have significant spatial and temporal heterogeneity. From November to March, the main factor is the runoff in the preceding month, the contribution of which can be more than 85%; from April to May, the runoff is significantly affected by snow, and its contribution in May is more than 65%. The snow affecting the runoff is mainly located near Gangtuo station and Batang station, and its influence has a time lag of about one month, In June, the influence factors of the runoff are quite complicated, and the contribution of the early runoff, rainfall, snow, evaporation and soil water content is relatively close; from July to September, the runoff is mainly influenced by the rainfall above Batang station, its average contribution being more than 50% and higher than 80% in August. Runoff in July and August is mainly affected by the rainfall in the same period, and in September is mainly affected by the rainfall in the preceding month. In October, the main influence factors are runoff and rainfall of the preceding month, and their contributions are more than 70%