The Hydrologic Cycle Characteristics And Affecting Factors Of Human Activities In The Taohe River Basin

The Taohe River, As one of the largest tributaries of the Yellow River, carrying an important step of water resources allocation in Western China, especially in Gansu Province, directly affects the economic and social development level in central Gansu Province and its surrounding areas. Researching on the hydrological cycle characteristics, as well as discussing the influence factors of human activities in Taohe River Basin can provide the theoretical basis to guide the water allocation program of the fully operational Taohe River Water Diversion and Supply Project, the exploitation and utilization of water resources and management and further the regional environmental protection and the economic and social development.In this paper, the study area is Taohe River Basin. Firstly, by using the average monthly hydrological data (runoff and precipitation) during 1956-2010, the annual distribution characteristics of the hydrological elements such as runoff and precipitation is quantitative studiedthrough the methods of asymmetrical coefficient, completed adjustment coefficient andPCD&PCP; the inter-annual variation features of runoff and precipitation is quantitative analyzed through the methods of trend coefficient, Mann-Kendall trend test and Rescaled Range Analysis and the mutability of runoff and precipitation is analyzed through the methods of order cluster analysis and Mann-Kendall mutation test. Secondly, the similarities and differences between the variation features of runoff and precipitation is analyzed by contrasting. Finally, the influence of human activities on the hydrological cycle of Taohe River Basin is quantitative analyzed by using the double mass curve of runoff and precipitation and then is confirmed through investigatingthe land use changes, water resources development and utilization and water conservancy project constructions. The results show as follow:(1) Themonthly runoff distribution of the Taohe Riveris extremely non uniform.However, thenon-uniformity and concentration of runoff has remitted since 1980s. The annual and the average monthly runoff have a significant tendency to decrease in general. And the trend in the future will be consistent with the current decrease. The mutational moments of the annual runoff upstream and downstream are almost identical.(2) The monthlyprecipitation distribution of the Taohe Riveris extremely non uniform. However, the non-uniformity and concentration of runoff has remitted since 1980s.The annual and the average monthly precipitationhave a tendency to increase upstream while a tendency to decrease midstream and downstream. However, the trend is not significant in general, and the dependency of the trend in the future is not strong. The mutational moments of the annual runoff upstream and downstream are hardly identical. The mutational moment upstream is earlier than that downstream.(3) The quantitative analysis of human activity factor influencing ratio not only verifies that the runoff and the precipitation changed dramatically in the Taohe River around 1985, but also explains the difference between the variation characteristics of runoff and precipitation midstream and downstream, where the human activity factor influencing ratio is larger.(4) Forest, grassland and farmland are the main land use types of Taohe River Basin. The main variation of the area of land use during the time from 1980 to 2005 in the Taohe River Basin is that the area of building-land increased while the area of forest, grassland and farmland decreased. Both in 1980 and in 2005, it is found that the farther downstream, the higher level of land development and utilization.