韭园沟流域淤地坝系综合风险预警

Comprehensive risk assessment of check dam system in Jiuyuangou watershed

病险淤地坝会严重地威胁到群众生命和经济财产安全,制约黄土高原地区水土保持生态建设的健康发展,因此淤地坝运行风险的识别和研究就尤为重要。以黄土高原淤地坝建设示范流域韭园沟流域淤地坝为研究对象,通过资料收集、水文统计、数值模拟等方法,从损失风险、结构风险、洪水风险和运行管理风险4个准则层选取10个指标,构建多目标多层次风险预警体系,基于专家打分结果采用模糊层次分析法确定指标权重,最终根据综合得分评价韭园沟流域淤地坝系风险状态。结果显示:1)韭园沟流域淤地坝运行管理风险的等级最高;大部分淤地坝结构风险为轻度风险状态;洪水风险和损失风险随着降雨重现期的增加而增大。2)当设计暴雨由10年一遇提高到300年一遇时,韭园沟流域淤地坝中处于重度危险的淤地坝比例从0增加到5.3%,轻度危险的淤地坝比例从60.5%降低到42.1%。本研究模拟不同重现期降雨下淤地坝运行风险,为淤地坝运行管理提供科学依据。

[Background]Sick and dangerous check dams will seriously threaten people’s lives and economic and property safety,and restrict the healthy development of soil and water conservation and ecological construction in the Loess Plateau.To promote the ecological protection and high-quality development of the Yellow River Basin,it is particularly important to identify the risk factors of check dams,ensure the safety of people’s lives and production,and promote local economic development.[Methods]Check dams in the Jiuyuangou watershed,which is a demonstration basin of check dam construction on the Loess Plateau,were taken as the research object.To build a multi-objective and multi-level risk early assessment system,10 risk assessment indicators were selected from the 4 criterion levels of loss risk,structural risk,flood risk and operation management through data collection,hydrological statistics,and numerical simulation,the indicator weights were determined based on expert scoring results using fuzzy analytic hierarchy process,and the risk status of check dam systems in the Jiuyuangou watershed were finally evaluated based on the comprehensive score.[Results]1)The operation management risk level was the highest among the four criterion levels,which was a severely dangerous state for most check dams due to the ineffectiveness of check dam management.The structural risks were of most check dams in a mildly risky state as most check dams were rarely damaged,and the junction of the discharge structure and the dam body also worked well.The flood risk and loss risk increased with the increase of the rainfall return period.The flood risk of most check dams was in a moderately risky state,but the risk rate increased greatly when the designed rainstorm increased from 10 years reappearing period to 300 years reappearing period,the loss risk of most check dams were generally safe when designed rainfall was 10 years reappearing period and became mildly dangerous under 300 years reappearing period.2)When the designed rainstorm increased from 10 years reappearing period to 300 years reappearing period,the severely dangerous check dams increased from 0 to 5.3%,the mildly dangerous check dams decreased from 60.5%to 42.1%.The risk of check dam system in Jiuyuangou watershed increased with the increase of the designed rainstorm.[Conclusions]This study assessed the operation risks of the check dam system in the Jiuyuangou watershed under different rainfall return periods,which may provide a scientific basis for the operation and management of check dams,toensure the safe andstable operation of check damsand lay a foundation for the establishment of safety emergency mechanisms and operational measures.