Analysis Of The Conditions And Trends Of Water And Sediment In The Weihe River Basin

The Weihe River is the biggest and much sandy tributaries of the Yellow River and its water and sediment comes from different source areas. Its sediment is from the upstream of Linjiacun and Jinghe River mostly, which is a tributary of the Weihe River. Its water is mainly from the area between Linjiacun and Xianyang. The factors of affecting water and sediment are climate and human activities in the Weihe River Basin, and the influence of the later is increasing. So it is important that the influences of rainfall and human activities are studied in the Weihe River Basin. The following works are conducted in this thesis:(1)The sources and distributing of water and sediment in the Weihe River Basin are studied, which of various intervals are compared. The new characteristics of the Weihe River's water and sediment in 1990s" are indicated that the water volume in 1990's is reduced 6.143 billion m3. about 63.8%, compared with that os 1960's in average; and the sediment reduced 0.2089 billion t. about 47.9%, compared with that os 1960"s in average. It means that the water reduction is larger than that of sediment.(2)The effects of rainfall on the runoff and sediment in the Weihe River are studied. It is pointed out that the rainfall is much less than the average.especially during the flood season, which results in the lower runoff yield.(3)The impacts of human activities on the runoff and sediment in the Weihe River are studied. It is pointed out that because of irrigation, reservoir construction, soil and water conservation measures, and warping dam; the water and sediment is reduced. During 1990's, the impacts of human activities excess that of rainfall.(4)According to the degree of watershed managemeng of the Weihe River and ite tributaries, the trend of water and sediment variation in 2010 and 2020 are forecasted. The result shows that in 2010 and 2020 the water volume will decrease 0.406 and 0.599 billion m3, and the sediment will decrease 0.0706 and 0.1044 billion t, respectively.Based on above analysis, it is pointed out qualitatively that the impacts of human activities already excess that of rainfall, becoming the main affector. And the major measures for reasonable utilization of water resources in the Weihe River Basin are as follows: saving water in every aspects, preventing water pollution, and spreading the soil and water conservation work.