Research On Hydro-ecological Effect Of Damming Rivers In Mid-lower Yangtze

The construction and operation of water conservancy projects, satisfied the requirements of human for power generation, flood control, irrigation, water supply. But also changed the ecosystem of natural rivers in the meantime, produced a series of influence, such as broke the continuity of the river, affected the ecological environment of the river, threatened the survival of aquatic organisms in river. Researching the effect of damming on the river, which has important theoretical and practical significance. Which is more correct to know and understand of the river ecological environment, better to keep the healthy life of river ecosystem. So as to realize the harmony of human and water.Selected the mid-lower Yangtze river as the study area, the observed data on ecological hydrology of Yichang station in 1956~2011 as the research data, the Yichang river section controlled by the Three Gorges project and Gezhouba project as the research object, carry out the research on hydro-ecological effect of damming rivers, analyzed the effect of hydrological regime’s changes on Chinese sturgeon’s habitat environment, so as to provide the restoration measures for protection of the Chinese sturgeon population resources. Which draw the following conclusions:(1)Based on the analysis of river ecosystem’s structure and function, discussed of ecological flow’s definition, calculation methods, and other related concepts, and analyzed of the effect of water conservancy projects on abiotic factors and biological factors in river ecological hydrology.(2)The comparative analysis of the three gorges reservoir downstream yichang station nearly 56 years of flow, temperature, concentration of hydrological sequence trend evolution using the linear trend estimate method and Mann-Kendall nonparametric rank correlation test method.The results show that,dry season flow of the Three Gorges section of the river downstream of the reservoir showed an overall upward trend,rest of the year showed an downward trend.The temperature of the autumn, winter and early spring showed a significant upward trend,the rest of the month show a downward trend.Sediment concentration throughout the year showed a significant downward trend.Analysis of the DAMS on downstream river hydrological elements of interannual change, concluded that the effect on the natural state changes is bigger,and the influence of the three gorges project was deeper.(3)The change of hydrological impact on Chinese sturgeon habitat of downstream of the three gorges reservoir,using the method of principal component analysis,extract the flow and temperature as the main factor which affect breeding habitat environment.Explained that the occurs of Sturgeon spawning activity,required under the premise of the water temperature reaches the allowable value.When the spawning grounds in the lower basin to increase traffic, caused when the hydraulics condition of water levels, sediment concentration and flow rate can cause the occurrence of spawning range,the sturgeon spawning behavior will occur(4)The change of hydrological impact on Chinese sturgeon habitat of downstream of the three gorges reservoir,using the method of principal component analysis,extract the flow and temperature as the main factor which affect breeding habitat environment.Explained that the occurs of Sturgeon spawning activity,required under the premise of the water temperature reaches the allowable value.When the spawning grounds in the lower basin to increase traffic, caused when the hydraulics condition of water levels, sediment concentration and flow rate can cause the occurrence of spawning range,the sturgeon spawning behavior will occur.(5)The restoration measures of the Three Gorges reservoir downstream ecological protection of important fish. Respectively discussed from the three aspects: engineering measures, non-engineering measures and management measures. The engineering measures including fish measures, artificial simulation of spawning and layered water intake, non-engineering measures including artificial enhancement and real-time monitoring, management measures including ecological regulation and government legislation. As while as the legislation protection, the government should strengthen supervision, making all kinds of protective measures of the Chinese sturgeon into effect.