Analysis and projection of runoff variation in three Chinese rivers

Abstract

Runoff variability is investigated separately for the Wei, the Bei, and the Qing Rivers in China with a focus on their respective differences in monthly flow patterns and flow duration curves (FDCs) between years with and without annual runoff deficit. The number of deficit runoff years increased in the Wei River and changed slightly in the Bei and Qing Rivers, respectively. Monthly flow variation patterns and FDCs differ between deficit and non-deficit years. The deficit years generally demonstrate earlier and more dispersed flow maxima. Deficit runoff years are contingent with the negative phase of the Polar-Eurasian Oscillation and vice versa, while generally they show contingency with the positive phase of the SST (Niño 3.4) and vice versa. The correlation between the human activity factors and the weights obtained by decomposing the runoff series into empirical orthogonal functions indicated that the human impact on the runoff variation was detectable: 22–25% in the Wei River, 28% in the Bei River, and negligible in the Qing River. We projected FDCs by weighting the distinctly different FDCs for deficit/non-deficit years according to several precipitation scenarios.