Evolvement analysis about rainfall-runoff in the upper stream of Li River under the changeable environment

摘要

Comprehensive study about the development of the precipitation and runoff in Li River was taken by using such methods: regression analysis method, Mann-Kendall rank correlation test method, sequential clustering method and mean value test method. Further the influence caused by the environmental change in the upstream of the Li River to runoff was analyzed. According to the results, the trend lines of rainfall, annual runoff and average annual runoff show insignificant raise, among which the one of rainfall is more remarkable than that of the other two ones. The effect of environmental change on annual runoff was analyzed by using BP neural network method. Then it was found that human activity has a relatively major effect. Since 1991 rainfall change has been the main influencing factor.