Study On Flash Flood Early Warning Method Based On Distributed Hydrological Model

With the work of flood prevention and flood disaster in the country steadily analysis and evaluation project has been completed,the distributed hydrological model can make full use of flood disaster evaluation survey and analysis of basic data and achievements,the problems exposed in the flood disaster prevention and weak links,research the key technology to carry out,so as to meet the higher demand of flood disaster prevention and control.According to the hydrological characteristics of semi humid and semi-arid area,micro cell infiltration model was improved based on the TOPMODEL model,at the same time in order to meet the needs of distributed early warning,based on sub watershed unit and distributed TIN respectively(Triangulated Irregular Network)to construct distributed routing framework by combining the characteristic of distributed hydrological model,first introduced ERIC(European Runoff Index based on simulated Climatology)early warning indicators,based on TIN distributed routing framework is proposed on the TRIC(TIN based Runoff Index of Climatology simulator)distributed early warning model,distributed early warning so as to realize the small watershed,and popularize Hongan River Basin in Shanxi province.First of all,using TOPMODEL as a prototype,combined with the hydrological,geological and climatic characteristics of semi-humid and semi-arid regions,a micro unit infiltration model is introduced to improve the TOPMODEL.The peak flow error,peak time error and the coefficient of determination of target using SCE-UA algorithm for parameter calibration,the calibration results and parameters of GREEN-AMPT TOPMODEL model and TOPMODEL model based on the prototype infiltration rate were compared,the simulation effect of micro cell infiltration model based on TOPMODEL is the best,the peak flow qualified rate of 60%,the peak time of 60%,and the deterministic coefficient of 0.26,the improved TOPMODEL can be used in Shanxi province.For the sensitivity analysis of influence parameters on the improvement of the model,the sensitivity analysis method of partial parameters is applied,the results show that the parameters SZM,T0,Srmax,Chv had the highest sensitivity,which can provide a basis to determine the parameters in the process of building the distributed model.Then,the TOPMODEL model of coupled micro element infiltration model is applied to the sub basin scale.Sub watershed unit division is based on the high resolution DEM to select the appropriate threshold,each sub watershed unit coupled micro unit into TOPMODEL model by runoff infiltration model sub basin outlet.With the help of network convergence according to the topological relationship framework,in order to meet the requirements of different river routing,improve the model’s ability to adapt,respectively using Muskingum method about channel flood routing model,SWAI model,river flow diffusion wave model to establish network exchange flow model,sub basin by element calculation so as to obtain the export section until,the process of the whole basin water outlet section.Some model parameters of each bus unit is determined according to the parameter sensitivity analysis results,the rate constant is found on various model combination parameters,the best simulation results of SWAI models,the peak flow rate,peak time,the overall pass rate of 90%,the deterministic coefficient were 90%,0.7,can be used as the channel routing model.Then,in order to reduce data redundancy and improve computing efficiency,the TIN grid is used to build the distributed model.Each node corresponds to the TIN grid as the Tyson polygon confluence unit,the construction of distributed routing framework based on grid scale;each grid unit flow through the coupling model,grid computing between confluence is described by introducing the concept of transit flow;model parameters of TIN unit is divided into three types,the value from the whole basin and the sub watershed values from the grid unit attribute value.The 21 floods into the coupling model of TIN bus based on the framework to verify the overall uncertainty coefficient is 0.5,the peak flow of qualified rate is 76.19%,peak time pass rate of 80.95%,the overall simulation results is ideal to meet the requirements of flood warning.Finally,by studying the commonly used distributed early warning methods at home and abroad,TRIC distributed early warning method is proposed.Based on the coupling model of TIN bus framework for the first time on the introduction of ERIC early warning indicators,and put forward the TRIC early warning model and early warning indicators were selected from 1970 to 2016;11 large flood data to determine the TRIC distributed early warning indicators,get the Honganjian river time distribution of different cumulative distribution of early warning indicators;a flood last into 2013 early warning calculation,the output of each grid in different periods including transit depth and through TRIC distributed early warning index to judge whether each unit warning.This method in Shanxi province Honganjian River Basin application effect is good,is of great significance to enhance the ability of the basin mountain flood warning.