Analysis on the Change Characteristic of Runoff in Three Different Climate Regions of China

Abstract:

According to the daily runoff data from 17 hydrological stations in Wei River(WR) basin, Huai River(HR) basin and Beijiang(BJ) basin, this paper choose annual runoff coefficient of non-uniformity, concentration period and concentration ratio and their timing features of these three basins to study the change characteristic of runoff in different climate regions of China. Results show that regional difference of annual runoff distribution does not only exist among three basins but also in each station in the same basin. Non-uniformity coefficient of annual runoff distribution in BJ basin is smaller than that in WR and HR basin. Meanwhile, the concentration- period in BJ is earlier than the others. As for the trend of these characteristics, it can be drawn from the computation that the coefficient of non-uniformity appear to decrease in BJ basin while in WR basin, except it’s obviously growing in Linjiacun station, the coefficient doesn’t show obvious trend, so do all the stations in the HR basin. In these basins, the distribution of concentration-period in one year is stable and close to a periodic variation. Mann-Kendall non-parameter statistical test is utilized here to get the variation trend of monthly and annual runoff series. Results show that Wei River basin shows significant reduction trend in annual runoff. The measured runoff data show that the annual runoff reduces weakly in HR although large discrepancy exists among each station. Compared to other 11months, an abnormal trend exists in June in HR basin for its highest MK value. And a more apparent down-ward trend is shown in the north than that in southern basin. As for the BJ basin, it’s obvious that statistics in flood season are higher than in non-flood season, and the trend in northwestern mainstream is more evident than that in southeast. InHR basin, the runoff change characteristic can be verified reasonable by analyzing the similar change features in precipitation. In BJ basin, there is a good correlation between precipitation and runoff, however, no trend exists in precipitation, but runoff series shows a weak rising trend, which indicates the influence from human activities. These finds could help to know the change characteristic of runoff in specific climate region in China more thoroughly.