Study And Application Of Flash Flood Disaster Early Warning System Based On Hydrological Model

Flash flood disaster not only destroyed infrastructure and residents' property,but also posed a great threat to the lives of the people.Taking the urgent need of disaster prevention and mitigation in Zhejiang Province as the starting point,this paper analyzed the problems faced by flash flood prevention in Zhejiang Province,and put forward the necessity of the study on flash flood early warning.Then,the research progress of hydrologic models in mountain torrents at home and abroad and the current research progress of flash flood early warning technology were reviewed in this paper.On this basis,taking the Shouchang River basin in Jiande county,Hangzhou City as the research object,using hydrometeorological data,soil data,expert experience and other information,a suitable hydrological model was constructed to carry on the early warning to the flash flood disaster.At the same time,this research developed the corresponding flash flood disaster early warning system.The following research results are obtained:(1)Study on applicability of hydrologic model in hilly area.Based on hydrological data from 1975 to 2001,using DEM digital elevation model generated by GIS,Xin'anjiang model and HEC-HMS model were used to simulate rainfall-runoff process in Shouchang River basin and then compare the accuracy of each model.The results show that the two models were applicable in Shouchang River basin,but of Xin'anjiang model were better in accuracy and fitting degree.Although the HEC-HMS model was a semi-distributed model,due to the sensitivity of its parameter CN,the total runoff depth of the simulation results was larger and the Nash coefficient was lower.The stability of the model was not high,and thesimulation effect in Shouchang River basin was not as good as Xin'anjiang model.Xin'anjiang model was put forward when summarizing and analyzing Xin'anjiang River basin in Jiande City.It had been widely used in humid areas of southern China.The Nash coefficient of Xin'anjiang model study was better,with the qualified rate96.29%,and the fitting degree was higher.Therefore,Xin'anjiang model was more applicable in Shouchang River basin.(2)Study on analysis method of early warning Indexes of flash flood disaster.Taking six typical villages in the Shouchang River Basin as an example,with two typical threshold as early soil moisture content(Pa = 0.75 WM and 0.90WM),Xin'anjiang model was used to determine the critical rainfall through continuous trial calculation respectively.Finally,considering the characteristics of rainfall,topography and geomorphology,and the characteristics of underlying surface,the critical rainfall early warning index was obtained by comparison and analysis,and the relationship curve between rainfall early warning index and soil moisture content in different periods was drawn to realize the dynamic early warning.(3)Research and application of flash flood disaster early warning system.Based on the analysis of dynamic early warning index of flash flood in small watershed,the platform of flash flood disaster early warning system was established.The system was designed with B/S architecture,and used Java language,Web Service and GIS technology to communicate and display,to realize the functions of data storage,query,early warning result release and visualization,and to provide services for flash flood early warning decision-making and so on.This system can further improve the early warning and prevention ability of mountain flood disaster at the grass-roots level.