Study On Theory Method And Application Of Ecological And Environmental Water Requirement Of River

Ecological Water Requirement (EWR) is the main research content of Eco-Hydrology. It is important to the rational allocation and utilization of water resources and to the ecological environmental construction. Presently, the study about the ecological and environmental water requirement is underway, so the relevant theories and research methods are needed to develop immediately. Through analyzing and summarizing the achievements of the previous studies, this paper continued a deeper study than before.Firstly, this paper outlined the studies regarding the ecological and environmental water requirement to distinguish the broad sense and narrow sense of ecological water requirement, the ecological water requirement and ecological used water, and the ecological water requirement and environmental water requirement at national and international levels. From Ecologic and Hydrologic point of view, through analyzing the thyroidal on the basis of EWR, this paper firstly pointed out that the research of EWR should follow the Holism theory, species diversity theory, Shelford theory, dissipation theory, river corridor theory of Landscape Ecology, the hydrological cycle theory and the carrying capacity theory of water resources. The thyroidal basis of the research methods about EWR directs the reasonable ascertainments of the time scale, space scale and protected projects in research.Secondly, this paper determined the difference between the water used for self-purging (WUS) and water transferred for purging and dilution (WTPD) and their proper application. Through computing the water environmental capacity, the respective contribution rates of the point and the non-point pollutant source were analyzed, self-purging and self-dilution models of inland rivers, river network and rivers affected by tides were developed in this paper. This paper pointed out the deficiency of the definition of WTPD and analyzed its positive and negative influences. As well, the paper provided the application conditions of WTPD and principles about how to choose pollutant indexes.According to the river corridor theory, it was derived that the natural oasis in arid area is the river corridor in fact. The paper proposed a research method considering EWR of the river corridor as EWR of the natural oasis and thus developed an EWR model for arid areas. The model was applied to Egia district as an instance to directly calculate the EWR of arid areas and the results met the practical condition very well.The paper further illustrated that the required buried depths of groundwater at different protected distances corresponded with the different buried depths of groundwater at the riverbank based on water sources of non-terrain vegetables and the river corridor theory. So a mathematical model was exploited according to the relationship among buried depths of groundwater respectively at the riverbank and at protected distances, and protected distances. This model is capable of reflecting the practical situation and is an indirect method for calculating EWR of the arid area.Lastly, the paper analyzed the relationship between the economical and ecological used water, the natural and human factors of the latter as well. A concept model was offered for ecological used water, which subjected to the ecological ideology and management system of human society, to the change of land, water transfer and waste discharge of economical society, and to the ecological system structure, environmental factors of natural society. On the basis of the above, ecological water requirement ratio was put forward firstly as an assessment factor and using the ecological used water ratio, the availability of water resources of the natural ecological system is derived. Comparison of the ratio of ecological used water and ecological water requirement also provided a research method of evaluating the river basin's sustainable development. Furthermore, an assessment index system of EWR of the river basin was proposed by referencing the Montana method. By taking the seven big ri...