Yonghui Yang: Sustainable Agricultural Water Management in Regional Scale

Dramatic Changing Period of Runoff and its Major Driving Force Agricultural Water Use in Haihe River Catchment

Yonghui Yang and Fei Tian

Haihe River Catchment is a sensitive region of human activities and climate change.

In this study, precipitation and runoff recorded at 27 meteorological stations and 8 hydrological gauge stations representing 8 sub-catchments of Haihe River Catchment during the past 40 years were analyzed to reveal temporal trends and dramatic changing period of runoff decrease. The trend analysis with the help of sequential versions of nonparametric statistical Mann-Kendall test detected the dramatic changing period of runoff decline. Results suggested that (1) annual precipitation in the most stations, only two exceptions, showed no significant trend, neither increase nor decrease, at ？？ = 0.05 significance level, (2) changing patterns of runoff are different in different part of Haihe River Catchment. Significant downward trend of annual runoff is detectable at 5 subcatchments at 95% confidence level, while trend in the left 3 subcatchments is not,(3) Dramatic decline of runoff in most sub-catchments took place between 1978 and 1985, the beginning of China’s land reform, (4) When farmland cover was higher than 25%, or forest and grass land cover lower than 75%, runoff in a catchment was dramatically decreased. Increase in farmland cover and decrease in forest and grassland cover were major factors of runoff decline. These results clarified that agricultural water use is likely the most important driver of runoff decline in Haihe River Catchment.