Method for predicting diversion ratio change of distributary channels of two-stage bifurcated riverway in the downstream of reservoir

Abstract

The invention provides a method for predicting diversion ratio change of distributary channels of a two-stage bifurcated riverway in the downstream of a reservoir. The method comprises the following steps that a planar two-dimensional water flow mathematic model is established, and parameter calibration and verification are performed; the flow range from the minimum flow to maximum flow of a target river section is equally divided into multiple flow levels, and statistics is conducted on the diversion ratio of the two distributary channels at all flow levels; variation diagrams of the diversion ratio with flows of the two distributary channels are respectively drawn, and linear fitting is performed to obtain slope and an intercept; according to values of the slope and the intercept, the types of the distributary channels are defined; it is predicted that the variation trend of the diversion ratio of the two distributary channels is main waxing and distributary waning or main waning and distributary waxing. According to dynamic change indexes of the diversion ratio of the distributary channels and the flows, the distributary channel of the two-stage bifurcated riverway is divided into a flood tendency distributary channel and a water shortage tendency distributary channel, the diversion ratio of the distributary channels is dynamically related with hydrodynamic conditions, the diversion ratio change of the distributary channels of the bifurcated riverway is accurately predicted according to hydrological change characteristics of the downstream of the reservoir, and planning and design of an airway is further promoted.

Description

technical field [0001] The invention relates to the technical field of water conservancy and water transportation engineering, and proposes a method for predicting the diversion ratio change of a two-stage branched river in the lower reaches of a reservoir, so that the diversion ratio of a branch river can be linked to the hydrodynamic conditions and hydrological processes of its development, which is beneficial Route planning of branched rivers. Background technique [0002] The diversion ratio of branched rivers is transported in different parts, and the diversion ratio of each branched river fluctuates frequently, which is not conducive to the safety of flood control and the stability of the navigation channel. The prediction of the diversion ratio of branched rivers is of great significance to the planning and construction of waterways. Existing studies have divided branched rivers into main branches and branch branches according to the dry water diversion ratio in branc...

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Problems solved by technology

Existing studies have divided branched rivers into main branches and branch branches according to the dry water diversion ratio in branched rivers, which cannot reflect the evolution characteristics of branch river diversion ratios with hydrodynamic changes. For example, after the impoundment of the Three Gorges Reservoir, the branch channel downstream of the dam has two different characteristics of main length and branch disappearance and main branch and branch length under the same water and sediment conditions. The existing diversion ratio prediction methods cannot explain this phenomenon.

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