A Calculation Method for Bimodal Flood Hydrograph Shape under Design Conditions

Abstract

The invention discloses a method for deriving a bimodal type flood hydrograph shape under a design condition. Data of the largest flood hydrograph of a reservoir over the years is collected; furthermore, the corresponding time-interval flood flow is obtained by calculation; the largest flood hydrograph over the years is normalized, so that a corresponding unit flood hydrograph is obtained; on the basis that the normalized unit flood hydrograph is optimally fitted by adoption of a mixed probability density function so as to obtain flood shape parameter series, frequency analysis of the flood shape parameter series is carried out; a flood shape parameter value under a design condition is obtained by calculation; and therefore, the bimodal type flood hydrograph shape under the design condition is derived. The invention provides the method for deriving the bimodal type flood hydrograph shape under the design condition based on the mixed probability density function; the statistical theory basis is relatively strong; the method can accord with storm flood characteristics of runoff generation and convergence under the design condition better; and thus, practical requirements on the bimodal type flood process in engineering design of large and medium-sized reservoirs can be satisfied better.

Description

technical field [0001] The invention belongs to the field of reservoir flood control planning and design, in particular to a method for deriving the shape of a bimodal flood process line under design conditions. Background technique [0002] The flood control safety design of large and medium-sized reservoirs in my country is generally based on the design of the flood process line. The current procedure for formulating the design flood hydrograph method is to first obtain the design flood peak discharge and design period flood volume in a specified return period through flood frequency analysis, then select a typical flood hydrograph shape from the measured data, and use the same multiple ratio or Calculation of Design Flood Process Line by Amplifying and Calculating the Same Frequency Method [1] . This makes the selection of the shape of the typical flood hydrograph have an important impact on the construction scale and operation management of water conservancy projects. ...

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Problems solved by technology

[0005] However, the existing technology can only provide the shape of the unimodal flood process line under the design conditions, which has great limitations and cannot meet the actual needs of the bimodal flood process in the engineering design of large and medium-sized reservoirs

At present, there is no literature on the derivation method of bimodal flood hydrograph shape under design conditions

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