Multitude Scale Features And Cause Of Formation Analysis Of Runoff And Sediment Discharge On Wavelet In The Lower Yellow River

Huang He River is one of the most difficult to bring under control in theword. Huang He River’s relatively obvious characteristic is that it contains moresand than water, and also it’s inharmonious while transporting sand and water.This means, in the downstream of the river, the watercourse is in an intenselyelevated situation, and approximately the riverbed is elevated averagely about0.08meters high every year. In present, the riverbed of downstream is ordinarilyabove five meters high compared to the two banks of the river wall, whichshapes “a river above the ground”.With the rapidly increased population anddevelopment of economy near the river, the water supply is successivelyincreased, the usage of ecological water is largely occupied in the water course,and the relations of the water and sand of the river continue to developinharmoniously in the future, which results atrophy of the main river course,lowered capability of draining off floodwaters for river course and the problemof worsened water quality contained in the water. So the research of the feature changes and influencing factors between river and sand in the downstream forHuang He River is an important significance.The characteristics and influence factors of water and sediment from thefour sites Huayuankou, Gaocun, Aishan and Lijin of the lower Yellow River inrecent60years from1950—2005were analyzed by using wavelet analysismethod, Yamamoto test method, double-mass curve method and so on.The results showed that: The trend of water and sediment series weredecline from1950to2005. The lower Yellow River,there are obvious periodicoscillation of5a,15a,21a for the runoff series, the first prime period is21a,which,the most significant periodic variation characteristics, and there areobvious periodic oscillation of7a,15a,20a for the sediment series，the first primeperiod is20a. To identify possible mutations in the21a scale, Yamamotoinspection method is used to carry out the further diagnosis,and to identify theabrupt changes in1971and1985for the runoff and1978,1985,1999for thesediment in the lower Yellow River.There are many factors that affect the change of water and sediment, whichmainly includes two aspects of nature and human.Human activity significantlydecreased the amount of sediment transport in the lower Yellow River，Theimpact of human activity on sediment transport was estimated by double-masscurve method，the results showed that：due to the influence of human factor，the accumulated reduce of sediment was54.41billion t in Huayuankou station，the accumulated reduce of sediment was47.96billion t in Gaocun station，the accumulated reduce of sediment was23.60billion t in Aishan station，theaccumulated reduce of sediment was19.77billion t in Lijin station Since thetwentieth Century80time.