Flood frequency estimation method considering historical flood

Abstract

The invention provides a flood frequency estimation method considering historical flood, and the method comprises the following steps: S1, selecting a proper frequency line type, and determining a to-be-estimated parameter; s2, collecting flow data monitored by the hydrological station, establishing an actual measurement flood peak sample sequence, and calculating and determining upper and lower boundaries of a to-be-estimated parameter; s3, collecting historical flood information, and constructing a historical flood sequence, wherein the information comprises quantitative historical flood information and non-quantitative historical flood information; s4, bringing the historical flood sequence and the actually measured flood peak sequence into a calculation sample, and constructing a parameter estimation likelihood function considering quantitative and non-quantitative historical flood information; s5, establishing an optimization problem by taking the likelihood function as a target function and the boundary of the to-be-estimated parameter as a constraint condition, and solving the optimization problem by adopting a genetic algorithm so as to obtain the to-be-estimated parameterof the frequency line type; and S6, calculating design floods in different recurrence periods according to the selected line type and the estimation parameters. Quantitative and non-quantitative historical flood information is brought into the sample sequence, the sample capacity and quantity of the flood sequence are increased, and the accuracy and representativeness of flood frequency parameterestimation and flood design are improved.

Description

technical field [0001] The invention relates to the field of flood frequency analysis, in particular to a flood frequency estimation method considering historical floods. Background technique [0002] In the planning and design of various water conservancy projects, the analysis and calculation of flood frequency is required to provide a basis for the determination of project scale and building size. The frequency analysis method is often used for calculation, which has high sensitivity to sample data. However, after most of the hydrological stations in my country were built in the 1950s, the measured flood series are relatively short, and even if extended by interpolation, the length of the data is generally only 40-60 years. Using the only extreme value samples with a length of several decades to estimate the once-in-100-year and once-in-a-millennium design floods will cause large errors, which is not conducive to the determination of the scale of water conservancy projec...

AI Technical Summary

Problems solved by technology

However, historical flood information records are not exhaustive. Only some historical flood information records are relatively complete, and there are still relatively few historical flood information related records, which makes it difficult to quantitatively estimate the flood peak flow, and some historical floods have been investigated, analyzed and measured. After that, only the magnitude or the positional relationship between each other is known, and the specific value of the flood peak flow cannot be estimated. Researchers of this kind of historical flood information call it indeterminate historical flood

In the current related research, there are few studies on the impact of indeterminate historical floods on frequency analysis. According to the work of the current named inventors, only quantitative or indeterminate historical flood information is used for flood frequency analysis in the prior art, and it is difficult to combine both. Flood-like historical flood information is included in the sample sequence for frequency analysis and calculation, which brings great difficulties to parameter estimation, and there is still room for improvement in the representativeness and accuracy of flood frequency analysis results

Images