Studies On Mountain Torrent Ditch Governance Priority Evaluation And Control Measures System In Chongqing

Torrent channel control is an important part of mountain torrents disaster prevention.Chongqing belongs to torrents ditch intensive areas and many torrents ditch need to be governed.Because of the limitation of historical and economic factor,flood control engineering measures were relatively weak.How to select the high degree of risk channel to control,only by virtue of relevant experience or subjectively qualitative judgment.Based on the analysis of flood channel characteristics,index system of mountain torrents ditch governance priority evaluation will be established,which provides an effectively quantitative method for screening a list of torrents ditch in Chongqing.This paper,taking 20 typical flood ditch as the research object,on the basis of literature review and field investigation,refines statistical analysis of the characteristic index of gully control section,and gets the classification of the importance and risk degree of gully control section on a single indicator:most torrents ditch is located in the areas filling large population,existing big catchment area,steep slope,serious siltation,weak flood control infrastructure and other issues.It establishes the assessment model of torrents ditch governance priority level by AHP in Chongqing,selecting 11 indicators(the basin population,the number of river basin administrative towns and villages,times of historical disaster occurrence,maximum rainfall of 24 hours,gully catchment area gully slope,gully average deposition thickness and forest coverage etc.).The result of assessment shows that the mean value of mountain torrents ditch governance priority level is 0.482,indicating the overall high degree of risk;2 items on high priority level;13 on moderate priority;5 on general priority.It is consistent with the practice,which shows that the model is effective and practical for the selection of the management order in Chongqing.According to previous results,the channel characteristics investigation and the results of torrents ditch governance priority assessment,we put forward the system of flood channel management measures for Chongqing,which consists of engineering measures of dike revetment,dredging engineering and other ancillary building project,combined with forestry engineering,agricultural farming plant measures and policy management measures.