Sesearch On Hydro-eco And Ecological Water Demand For Arid Areas

The arid regions are of vast majority, accounting for about 33% of land area in China, and for 73% of all the Northwest land area. There the climate is dry, precipitation is scarce, evaporation is strong, vegetation type is single, ecological environment is fragile. Water resources are constraints of all biological survival and human economic activities. Due to the extensive construction of oasis, the ecological and environmental protection are ignored, which triggers a series of hydro-ecological problems that restrict the conduct of of western development and the description of the blueprint of the beautiful landscape in northwest China as well as the socio-economic sustainable development of arid regions.Therefore, it is necessary to analyse the hydrological characteristics of arid areas systematically, and summe up the relationship between the hydrological and ecological problems in arid regions and ecological water demand in typical arid regions. Based on it, explore the calculation of ecological water demand appropriate for each of the component factors in arid regions, ultimately to provide a scientific basis for the gradual solution of the hydrological and ecological problems in arid regions.This thesis is divided into five chapters. Chapter 1 to chapter 4 are basical theoretical parts:chapter 1 introduces the background, purpose and meaning, and content. It mainly introduces the research advance of the hydroecology and the ecological water demand in arid areas and the technical route and innovation of this thesis; Chapter 2 analyses the hydrological and ecological characteristics and the problems in arid areas, and the mutual influence between the hydrological ecology and ecological water demand in arid areas; chapter 3 researches the theory of ecological water demand in arid areas systematically; chapter 4, after comparative analysis of the calculation of ecological water demand in domestic and abroad, combining of the hydrological characteristics of arid areas, explores for the calculation of ecological water demand appropriate for arid areas。The methods include the use of an improved Tennant method to calculate ecological flow of rivers, the use of domestic hydrology method to caculate ecological water demand, using quota estimation method to estimate ecological water demand of vegetation of artificial oasis (including urban oasis), using phreatic water evaporation method to calculate ecological water demand of vegetation of natural oasis, using quota estimation method to calculate the ecological water demand which maintains a balance between water and salt, using class quota estimation method to calculate the ecological water demand of artificial wetland ecosystems.Chapter 5 takes the example of Manas River basin which is one of the typical inland river basins in arid areas and analyzes the unique hydro-ecological characteristics systematically which includes scarce rainfall and big evaporation, closed and drought inland, significant vertical difference, weak ecological environment, etc. On this basis, it summarizes the mainly hydro-ecological problems exist in the Manas River basin systematically. In view of the mutual influence between the hydrological ecology and ecological water demand of the Manas River basin, it calculates ecological water demand of Manas River basin and river ecological flows.