Study On Hydraulic Methods Calculating Instream Base Flow Requirement

Eco-environmental water requirement is one of basal, important and pivotal factors to maintain, develop, resume and protect environment. It is the core issue to deal with the relationship of human being and ecosystem. Study of instream flow requirements(IFR) is the core of the ecological water requirements research in every country. Hydraulic methods is researched to calculate the instream base flow requirements(IBFR) in the thesis, the following contents are included:(1)On the base of collecting much research production of ecological water requirements, the concept and characteristic of ecological water requirements are analyzed, the sorts of calculating methods are researched, and characteristics of these methods are analyzed.(2)The functions and characters of river ecosystem are analyzed. The relationshi of flow and river ecosystem is researched.(3) Hydraulic methods are studied to calculate the IBFR, especially wetted perimeter method and velocity method.Considering the effect of river transect to the wetted perimeter, the wetted perimeter versus discharge relationship of different transects is analyzed. The breakpoint in the wetted perimeter versus discharge relationship is determined by the maximal curvature method. The fitting transects of the wetted perimeter method are analyzed under the same discharge, the conclusion presents rectangular and trapezoidal transects are more propitious to protect the aquatic habitat.From the viewpoint of protecting aquatic biotope, fish is deemed as target of river aquatic biology. The important hydraulic factor—velocity is selected as representative of influence fish existent factor. Confirming 0.4m/s as the fish fitting velocity, the velocity method theory is studied.(4)The IFR of 13 hydrological stations and 15 transects in 4 drainage basins are calculated using hydraulic methods, the main results are:a When calculating the IFR using hydraulic methods, the results are effected by transect patters, how the transect steady, the basin characters, and so on.b Adopting different methods at the same transect, the results of the IFR have obvious difference. The percent of the IFR comparing the average discharge at each station is...