Process And Risk Analysis Of Continuous Failure Of The Check Dam System

The loess hilly and gully region is one of the most severe soil and water loss region,ecological environment there is extremely fragile,and it is the main source area of the Yellow River sediment.Check dams play a huge role in soil and water conservation.Consequently,a large number of Check dams have been built on the Loess Plateau,forming a large number of dam systems in small watersheds.The flood control standard of the check dam is relatively low,some check dams are unreasonably configured and lack corresponding flood control and drainage facilities.Under the excessively heavy rain conditions,the water damage of the check dam often occurs.When the dam system in the watershed lacks a sufficient number of key dams to stop the rain and protect the downstream dams,the collapse of upstream check dams often causes a chain failure of the check dams downstream.Flowever,the check dams in the watershed are often in"small groups",and there are complex series and parallel relationships between the dams in the dam system.At present,there is still no method to study the chain failure of the check dam system.Therefore,it is important to establish a method that can reasonably predict check dam failure flood and its loss through the continuous flooding calculation of the check dam system in the small watershed,which can provide technical support for the safety prevention and control of the check dam system in the small watershed,and improve the emergency management of the check dam.The main research contents of this article are as follows:(1)To solve the complex failure mode of the check dam system,this paper establishes a calculation model suitable for the continuous failure of the check dam system based on the C language platform.The model contains the calculation the earth-rock dam breach program DB-IWHR and the "family tree" algorithm and the flood evolution process within the dam system.The model uses the "family tree method" algorithm to determine the order of the check dam failure,and then uses the DB-IWHR program to conduct the burst calculation to obtain the flood discharge process of the check dam,and finally evolves to the downstream check dam through the internal flood of the dam system.(2)Back analysis was conducted on the case of the storm flood of the "August 17th" in Dalate county,Inner Mongolia using the calculation model of the continuous dam failure of the check dam,and the DBFL-IWHR flood evolution program was used to evolve the outburst flood to the downstream Longtougua hydrological station to verify the reliability and stability of the model.The sensitivity analysis of the single dam calculation parameters and the continuous failure calculation parameters of the model is carried out,and reference suggestions are provided for the values of each input parameter.(3)According to the characteristics of the dynamic change of the collapse risk of the check dam system in the watershed,based on the back analysis of the continuous failure of the check dam system in Dalate county.Change the silt elevation of each check dam in the watershed and increase the spillway in different check dams of the dam system,and then conduct failure risk analysis through the continuous model of the check dam system to obtain the probability of failure of each check dam under dynamic changes of the check dam system.Provide guidance for risk prevention and control of check dam system.(4)The continuous flooding model of check dam was used to calculate the outburst floods in the Xiliu gully basin under the three schemes of rainfall of 300mm,350mm and 400mm,and the outbreak floods were evolved to the downstream river channels and obtain the submerged range of outburst floods.The life loss and economic loss of the dam break are calculated according to the flood submergence range,and finally the risk level is evaluated through the risk evaluation system.The reliability of the assessment model is verified by evaluating the flood loss of the Xiliugou outburst,which provides technical support for the safety prevention and control of the check dam system in small watersheds.