Early Warning Model Research For Check Dam Break Risk From Flood

Check dam is a dam structure constructed in all levels of ditches in soil erosion area,mainly used to stabilize and elevate erosion base point,retain silt,detain flood and cut peak.It plays an irreplaceable role in controlling soil erosion,reducing sediment inflow into the Yellow River,developing regional economy,improving people's living standards and improving the ecological environment.On the Loess Plateau,built a large number of check dam.However,while Check Dams play a role in retaining silt and increasing agricultural production,dam breaks are common because of their low flood control standards,poor quality and lack of management.The occurrence of dam-break of Check dam has brought a great threat to the safety of life and property.It is of great significance to establish a risk early warning system for flood control and dam break of Check Dams and to publish the risk early warning of dam break in advance to r,educe the losses caused by dam break.At present,the research on flood risk early warning of Check Dams in small watersheds mostly focuses on evaluating the current situation of Check dams,giving the flood control capacity of each Check Dams in Check Dams system,and failing to give real-time early warning level according to real-time rainfall.The purpose of this paper is to construct a real-time early warning model for the Check Dams break risk from flood,to improve the early warning system for Check Dams.The goal of the risk early warning model is to forecast the risk of dam-break by real-time rainfall before dam-break and to give early warning.Through the research of this paper,the following results are obtained:By analyzing the causes of dam break of Check dam,a risk index system for dam break of Check dam is established.The risk dam break is divided into hydrological risk and engineering risk.The hydrological risk is taken as the risk index by the height from the top of the dam.Engineering risk includes three parts:engineering quality,structural safety and seepage safety.Engineering quality is taken as risk index by foundation seepage control quality,dam seepage control quality and filling quality;structural safety is taken as risk index by dam deformation and slope stability;seepage safety is taken as risk index by dam foundation seepage,dam abutment seepage and dam body and seepage prevention body seepage situation.A risk early warning model for flood control and dam break of Check dam is constructed.The model consists of three modules:input,analysis and output.The input module input model applies the regional real-time rainfall and the Pre-flood engineering risk score of each Check dam.The analysis module obtains the real-time comprehensive dam-break risk grade of Check dam by analyzing the real-time input rainfall and Pre-flood engineering risk analysis.The output module gives the corresponding level warning according to the comprehensive dam-break risk grade.In the analysis module,firstly,the weight of each index layer to the risk of dam break is determined by analytic hierarchy process(AHP).Then the hydrological risk scoring method and engineering risk index scoring method are put forward.Based on the weight of each index to the risk of dam break and scoring,the risk scoring of comprehensive flood control and dam break of Check dam is obtained.The real-time risk grade of dam break is determined by the risk scoring of comprehensive flood control and dam break,and the corresponding level of early warning is issued by the risk grade.Taking Wangmaogou No.2 dam,Shidizui No.1 dam and Guandigou No.3 dam in Wangmaogou watershed as examples,the risk early warning model for Check dam break is applied.Firstly,ARCGIS is used to extract the area,water level and reservoir capacity curves of Check dams from DEM.Then the rainfall data are calculated by using the design rainstorm results of Suide Station in Yulin Hydrological Manual,and the rainstorm process of each frequency can be obtained according to the distribution of 6-hour rainstorm duration in Suide from Yulin Hydrological Manual.The actual rainfall is simulated by the rainstorm process.By inputting the simulated real-time rainfall into the model,the change of the warning grade of Wangmaogou No.2 dam,Shidizui No.1 dam and Guandigou No.3 dam with time is obtained.