Riverbed evolution analysis method based on flow weighted average streamline length index

Abstract

The invention discloses a riverbed evolution analysis method based on a flow weighted average streamline length index. According to a two-dimensional flow field of an object river reach and a streamline end point located at an outlet section of the two-dimensional flow field, the flow weighted average streamline length E _ LEN of the object river reach in N periods is calculated respectively, and the flow weighted average streamline length E _ LEN in the N periods is compared to achieve the quantitative analysis of the object river reach. According to the method, the quantitative depiction can be carried out on the mainstream and deep robinia swinging conditions of the riverway.

Description

technical field [0001] The invention belongs to a riverbed evolution analysis method, which is a method for quantitatively analyzing the plane changes of river channel form and hydrodynamic conditions, and is suitable for quantitatively describing the mainstream and deep flow of plane rivers with complex plane forms and frequent scouring and silting. Background technique [0002] Taking the plain rivers in the middle and lower reaches of the Yangtze River as an example, the changes in planar morphology are mainly analyzed through the length of the channel, contour lines (isobaths) in the channel, and deep-flow lines; the planar changes in hydrodynamic conditions are analyzed by the mainstream area and mainstream line. Due to the complexity of the channel shape and hydrodynamic conditions, the above indicators have certain limitations. For example, when the embankment is under control, the length of the river is basically fixed, which cannot reflect the adjustment and changes...

AI Technical Summary

Problems solved by technology

Due to the complexity of the channel shape and hydrodynamic conditions, the above indicators have certain limitations

For example, when the embankment is under control, the length of the river is basically fixed, which cannot reflect the adjustment and changes in the erosion and siltation of the beach channel in the river; the contour line (contour line) needs to be selected in conjunction with the specific river section, which lacks generality, and the plane shape It is also difficult to quantify in terms of description; indicators such as the deep-flow line, mainstream area, and mainstream line that are strictly defined are poor in smoothness or even discontinuous in natural rivers, and often require empirical judgment and processing, which is relatively lacking in accuracy and rigor

[0003]Limited by the lack of the existing index system, the quantitative description of concepts such as "straightening" and "sitting on the bend" in the riverbed evolution is insufficient

Especially during the drastic evolution period of the downstream riverbed after the construction of large-scale hubs, the plane adjustment of different river types lacks a consistent description. Also taking the middle and lower reaches of the Yangtze River as an example, after the Three Gorges Reservoir is impounded and operated, the curved river section is convex, concave and silted, and the branch section is short. Phenomena such as branch development can only be described qualitatively, and cannot be analyzed quantitatively

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