Study Of Ecological Water Requirement And Assessment Of Ecosystem Health In Small River Basin

Water is the source of life, the vital point of production, the foundation of ecology. Butwith the development of economic, the water crisis which can be characterized by watershortage and water pollution is getting worse and worse. Under the background, thecompositions and the calculation methods of the ecological water requirement in small riverbasin are discussed. And then the concept and the assessment methods of ecosystem health inriver basin are analyzed. At last the Huangqian river basin is applied.The following outcomes and conclusions are obtained in the paper:(1) Based on the research state of the ecological water requirement and the assessment ofecosystem health at home and abroad, the theoretical bases of them are analyzed.(2) Characteristics of ecological water requirement are analyzed. Learning from thecalculation methods of the ecological water at home and abroad, the compositions of theecological water requirement in small reservoir-watershed are studied. And it is divided intoinside and outside of river. And the previous can be quantified as ecological waterrequirement of the reservoir, while the latter can be quantified as vegetation water demand.After that, the calculation model of ecological water requirement is proposed.(3) The concept of ecological water requirement of the reservoir is proposed. Theecological water requirement of the reservoir is divided into seven parts: ecological waterrequirement of the upper river, ecological water requirement for transporting sediment, thewater demand of evaporation and leakage, ecological water requirement of habitat, the waterdemand of reservoir self-purification, the water demand to maintain downstream ecologicalhealth. The calculating methods of each part are proposed. When calculating the totalecological water requirement of river basin, each water demand has crossover andsuperposition and it is necessary that each water demand be combined availably according toespecial region status.(4) The concept of ecosystem health in river basin is proposed. The assessment system ofecological health is constructed from four categories of indicators: habitat indicators,biological indicators, socio-economic indicators and function indicators.(5) The indicators are weight by the health degree. And their weights are confirmed bystructure entropy weight method. At last, ecosystem health in river basin is evaluated by thecomprehensive health degree.(6) In case studies, the ecological water requirement in Huangqian river basin iscalculated. And the ecological water requirement inside of river is0.69271hundred millionm~3; the ecological water requirement outside of river is1.99998hundred million m~3; the ecological water requirement in Huangqian river basin is2.69269hundred million m~3. Alsothe assessment model established in the paper is applied in Huangqian river basin. Theoutcomes indicate that the ecosystem of the Huangqian river basin is sub-healthy.