| Huangfuchuan is one of the main tributaries in abundant sediment and coarsesediment region of the Yellow River. Huangfu hydrological station controlling areaaccounted for0.46%of the catchment area of the Yellow River Basin, the annualaverage sediment input into the Yellow River from1950to2005accounted for l4.1%of the total sediement discharge in the upper area from Sanmenxia. Water erosion isthe main erosion type in this watershed. The main factors affluencing the watershedsediment yield to climatic condition (rainfall) and surface conditions (topography, soiland vegetation). But not all the sediment caused by the erosive rainfall erosionproducts will immediately enter the rivers and become river sediment. Therefore, Weput forward the concept of watershed sediment yield rainfall, determine the standardof watershed sediment yield rainfall of Huangfuchuan Watershed, and analysis thewatershed sediment yield rainfall influence on runoff and sediment discharge. Themain findings are as follows:(1) There are downward trends and large interannual variability between theRunoff and the sediment of Huangfu hydrological station. The allocation for the yearwas concentrated in the June to September. According to the double cumulative curve,the runoff and the sediment were both volumed in1979and1997. Accordingly, theprocesses of runoff and sediment were divided into three stages.(2) We define the of the concept of watershed sediment yield rainfall anddetermine the watershed sediment yield daily rainfall standard12.9mm inHuangfuchuan river basin; Watershed sediment yield rainfall and the days ofwatershed sediment yield rainfall did not have downward trends and variability in1954~2010. Watershed sediment yield rainfall in June to September throughout theyear accounted for91.9%.(3) Runoff and sediment discharge were positively correlated with watershedsediment yield rainfall and number of rainy days of watershed sediment yield rainfall. According to the double cumulative curve, contributions of the watershed sedimentyield rainfall to runoff and sediment were73.5%and56.1%in the second phase,31.7%and23.9%in the third stage respectively. Contribution rates of watershedsediment yield rainfall reducing the runoff and the sediment were distinct weakening.(4) The runoff and sediment in June, July and August showed a significantpositive correlation. The watershed sediment yield rainfall in June, July and Augusthad a great influence on on the annual runoff and the sediment. Antecedent watershedsediment yield rainfall had a large impact on runoff and sediment of months later,especially in July and August.(5) By analyzing the runoff and sediment of typical year, and watershed sedimentyield rainfall, points out that that the decrease of Huangfuchuan water runoff andsediment discharge is not due to the watershed sediment yield rainfallis most. |
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