| Construction of reservoirs and other water conservancy projects to help humans function better use of the river and water resources, flood control and power generation efficiency, Hennessy played at the same time, changing the natural river water and sediment conditions, the evolution of the reservoir and downstream river lakes profound Tongjiang affected. Tongjiang lakes as a natural reservoir for water distribution basin plays an irreplaceable role, and the relationship between changes in rivers and lakes in turn determines the evolution of the lake towards the main stream, if the adjustment mechanism of the evolution of natural rivers lakes of water and sediment after the relationship changes Recognizing the trend is not clear enough, it can not properly evaluate the impact of water conservancy construction, will not be able to fully maximize the benefits of the project.Based on the analysis of Chenglingji water level and diversion from three causes changes on the Three Gorges Reservoir, clarifies the Three Gorges Reservoir on the Yangtze River-the impact response of Dongting Lake Dongting lakes relations and the role of the reservoir runoff regulation and summary Tongjiang lake itself and its feedback effects on the evolution of the Yangtze River into the sea runoff, based on the simulation of the upper reaches of the Yangtze River into the sea cascade reservoirs regulate runoff process. Finally impoundment before grouping sediment transport characteristics of the Yangtze River, downstream of Yichang Three Gorges Reservoir study-Chase station packet recovery sand.The main contents of this paper were as follows:(1) Analysis and optimization of the changes in the direction of scheduling since impoundment of the Three Gorges Reservoir, in determining its schedule based on trends established cascade reservoir operation model and validated with measured data, analyzes cascade reservoir capacity to deal with floods in the Yangtze River in the allocation and transfer after storage methods, focusing on the Yangtze River upstream reservoir Jingjiang flood restrictions against the discharged volume, the Three Gorges single library discharged volume of not less than49000m3/s, cascade reservoirs discharged volume of not less than46000m3/s Jingjiang can withstand100-year flood. (2) Clarify the operation of the Three Gorges Reservoir on the Yangtze River response relationship and influence Dongting Lake Dongting lakes reservoir runoff regulatory role. Jingjiang River Three Gorges Reservoir after impoundment of three is not a continuation of the trend of shrinking before the impoundment, water diversion to keep the former relatively little change, resulting in reduced factor of three minutes before the Jingjiang River water flow compared in Jingjiang80%reduction in runoff is a major factors that affect the regulation of the Three Gorges reservoir runoff accounted for20%, which is a secondary factor. Jingjiang Yangtze River upstream reservoir flood season flows leveling effects, reducing the diversion of Jingjiang three peak flow, but increased the total flood volume Jingjiang three shunt. River water level in the Three Gorges Reservoir quantitative decline of weakening export backwater effects on the Dongting Lake water. Taking these conclusions feedback Dongting Lake reservoir runoff regulation are:flood, flood reservoir downstream of the leveling process, making three large split ratio corresponding to the duration of the extension, into the lake flow is greater than the natural state, this time to assist the Yangtze River lakes against floods, flood greater than the natural state; impoundment of the reservoir water level caused by main stream down backwater lakes exports led to changes in the relationship between the lake traffic increases, weakening the impoundment of water downstream to reduce the adverse effects; in dry season, increase the flow of water resulting in less water in the lake, so reducing the lake runoff.(3) Clear lakes in Tongjiang under the influence of feedback effects on the upper reaches of the Yangtze River cascade reservoirs Yangtze River into the sea Odori Station runoff process, through the river lakes lake volume changes and feedback on the River runoff changes, overall little effect on runoff into the sea. And the great flood in the regulation process, the impact of reservoir flood runoff is not discharged into the sea traffic of the more obvious the smaller tanks, the discharged volume of more minor flood lasted longer discharged volume vacated when the flood storage capacity may encounter along the way, weaken the role of reservoir flood tanks into the sea on the runoff process.(4) Poyang Lake to Hankou-Chase coarse river erosion process significantly affected. Corresponding to each traffic class Hankou, lakes import flows accounted for the greater proportion of outbound traffic Chase, the Hankou-Chase River, the stronger the ability to mix the coarse sand. In the analysis of annual runoff on lake Hankou-when river erosion affected Chase found that sinks into the lake in runoff runoff proportion accounted Chase station and Hankou-Chase coarse river erosion and deposition are closely correlated, and when the proportion of more than19%, Hankou-Chase river silt to turn red.(5) Based on a long series of water and sediment transport data to study the Yangtze River in Yichang-Chase river scour stream and river sediment concentration relationship between the size of the establishment of a grouping each reach of the river erosion in the corresponding balance the correlation between the critical sediment concentration and river flows. Comparing the measured data before and after the impoundment, the results indicate that in the case of the sharp decline in upstream sediment mutation, if a group size of riverbed sand in sufficient quantity, then reach the amount of suspended sediment transport in the group can basically reach the exit of each flow reaches a critical level corresponding transport rate, and each level of each group sediment flow will not exceed the level before the impoundment. |
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