Study On The Change-points Diagnosis Of Runoff Process In The WeiHe Basin Guanzhong Section

The influence of human activities and climate change alters native state of river runoff. It brings about hydrological process variation on time and space, and the probability distribution of hydrographic factor sample sequence is changed around change point. Therefore, it brings some difficulty to frequency analysis and directly effects the program and exploit of valley water resources. This problem must be resolved in engineering practice.The WeiHe basin Guanzhong section is a typical area. In order to settle down the conflict between supply and requirement, human beings adjust the water resource by means of building reservoir, channeling off water and so on in a long time being. These large-scale activities bring adjustment to some extent for river surface-flow and change the nature state of river surface-flow. Meanwhile, serials of large-scale productive activities, such as development of land, water and soil conservation, ect, influence the condition of underlaying surface, thus arose the changes of the state of affairs of river surface-flow. It shows that in the 60s last century the river stream is gradually reduced, especially as it is known that the catchment yield decrease evidently after the 90s last century. In order to further definitude the law of the changes of the catchment yield of the Wei River, so as to provide scientifical theory for the research of reducing natural disaster and establishing the measure of governing water environment. Moreover, it could provide some experience for other valley. So the diagnosis to the change points of the Wei River valley runoff process has some reality and theory guidance meaning.The paper based on summarizing and concluding more than 10 kinds of diagnosis methods of the variation points hydrological process, find out the sliding rank-sum test, which are relatively brief, practical and effective methods. Then check and analyze the annual runoff of 6 gydrologic services of the Wei River Guanzhong section between 1956 and 2005, obtain the amount and position of surface flow serials change point of each station, the result show that sliding rank-sum test has better adaptability to muti-parameter change of hydrological serials of non-normal-distribution.Following conclusions are made after analyzing and demonstrating the paper:(1) Sliding rank-sum test has better adaptability to the diagnosis to the change points of the Wei River Guanzhong section and synergic curve partition method has worse result.(2) Two change-points exist in Linjia Village Station and Weijiabu Station of the main branch of the Guanzhong section of the Wei River, the serials of 50 years runoff can be divided into three periods:1956-1970, 1971-1993, 1993-2005.(3) Two more change points exist in Xianyang Station and Huaxian Station. The serials of 50 years runoff can also be divided into three periods: 1956-1968, 1969-1993, 1993-2005.(4) The main branch with Jingcun Station of Jing River and Zhuangtou Station of Beiluo River exist a evident change point.