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Benefits Analysis Of Debris Flow Prevention And Control Project In Hunshui Gully,Daying:River,Yunnan

Posted on:2022-08-29Degree:MasterType:Thesis
Country:ChinaCandidate:Z Z YangFull Text:PDF
GTID:2480306335457954Subject:Industrial Current Technology and Equipment
Abstract/Summary:PDF Full Text Request
Check dams have been realized take functions in storage,energy dissipation,slope stabilization,and gully consolidation,which consequently have been the most widely-used and effective structural intervention measures for the prevention and control of debris flows around the world.Though as a key content of debris flow research,existing researches regarding the benefit analysis of debris flow prevention and control project,which mainly based on the current situation,hardly reflect the process of debris flow prevention and control.There is still a lack of benefits evaluation of long-term debris flow prevention and control projects.After more than 50 years of prevention and control,the cascade check dam in Hunshui Gully(HSG)have been a model of debris flow prevention and control project in China that creates extremely high benefits on ecological and disaster prevention.In this study,the HSG of Daying River were selected as a study area,observed data of topography and debris flow activities in different periods were collected to study the long-term silting process behind check dams via analyze the disaster prevention benefit of debris flow prevention and control projects in HSG.The benefits of stabilized source-material in HSG were studied based on the vital role of cascade check dam in restraining debris flow.Ultimately,different restoration times of debris flow deposits were selected to analysis the long-term vegetation and soil productivity restoration process.thereby studying the ecological benefits of the prevention and control project.The main research results are as follows:(1)The cascade check dam have a distinct effect on disaster prevention.The frequency of debris flow reduced from>50 times a year to 2-3 per year during the control period,and check dams raised the erosion datum level by 152 m.The cascade check dam in HSG intercepted a total of 1.00842×10~7 m~3of sediment,while the debris flow silting along the mainstream and sedimentation rate increased first,and then decreased,and a headward siltation was observed at anaphase.(2)The construction of the cascade check dam and the headward siltation have greatly enhanced the stability of the mountain.Cascade check dam become functioning when the height of cascade check dam group remained the same as the height of shear crack of landslides.The cascade check dam stabilized 3.04088×10~7 m~3of source-material,which weakens the sediment yield in the basin and reduces the sediment output by more than 40 million m~3.(3)The restoration of vegetation and soil productivity in debris flow deposits were slowly.The community structure in HSG gradually became complete and the soil quality improved after more than 50 years of treatment.The results indicated that total potassium,p H and bulk density decreased,while other soil characteristics increased,in which soil productivity index and soil organic matter increased exponentially.It also revealed that the rehabilitation time of 23 years was most likely a threshold time for the restoration of vegetation and soil productivity at debris flow deposits.(4)The cascade check dam in HSG play a crucial role in debris flow prevention and control.The vegetation restoration in HSG stabilized the potential solid source of debris flow to a certain extent.This study reveals the long-term siltation patterns and the recovery process of soil productivity behind check dams based on the real filed study,as well as the benefit analysis of the long-term debris flow prevention and control project.The results can be used as the basis for the follow-up scientific prevention and control of HSG,providing a reference for disaster prevention and ecological restoration in the strongly active debris flow basin.
Keywords/Search Tags:Debris flow prevention and control, Efficiency analysis, Cascade check dam, Silting process, Stabilized source-material, Ecological restoration
PDF Full Text Request
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