Ecological Flow Requirements For The Middle And Lower Reaches Of The Yangtze River

This paper introduces the current research progress worldwide and its research perspectives on river ecological flow requirements and produces the ecological meanings of hydrological factor and hydrological characteristic and geography characteristics.As the human activities to the river, the river's nature function has been destroyed ,this paper discusses the main nature function of river, analyzing the human activity to the breakage of the river nature function, and put forward two measures.Since the construction of large-scale water resources projects produces to some degree negative impacts on the whole watershed, this paper investigates the disadvantageous effects of large-scale water resources projects on the ecological environment of water level-rising zones of relevant rivers and lakes, and their surrounding and downstream areas. Ecological flow requirements is an important research topic of Eco-hydrology. This paper discusses the ecological effect between hydrological conditions and hydrological characteristic, the importance of ecological flow protection and the definition of ecological flow, and presents wordwide methods to calculate ecological flow. Base the existing methods, this paper proposes two new calculation methods of ecological flow requirments, the least monthly ecological runoff calculation method and monthly frequency calculation method.Since second half leaf in 20 centuries because of the influence between the construction of large-scale water resources projects in the Yangtze River basin and other human activity, some important living creature cluster suffer to coerce. By the analysis of the relation between the biomass and the flow of Yangtze River, This paper studies the water living creature's needs to the hydrological conditions and hydrological characteristics.It must prevent the ecological flow requirments from destroying for guaranteeing ecology security in the Yangtze River. According to the theories of ecological hydrology the ecological flow are calculated and the trend of the flow variety in the Yangtze River are analysed in brief.