地面沉降对蓄滞洪区调度及风险的影响研究

Influence Analysis of Land Subsidence on Flood Dispatching and Risk in Detention Basin

综合分析大黄堡蓄滞洪区不同年份的遥感数据和水准点数据,可知该区域年均沉降量由1989—2002年的20,mm降至2002—2010年的12,mm,虽呈整体下降趋势,但总沉降量仍然较大.为提高分析的全面性,综合考虑了入流河道堤防沉降对蓄滞洪区的影响,数据分析表明堤防每沉降100,mm,河道泄流能力下降30,m^3/s,从而导致蓄滞洪区入流量增加.针对大黄堡蓄滞洪区采用交替方向隐式(ADI)法建立二维洪水演进模型,模拟结果表明:地面沉降对蓄滞洪区库容有影响,在设计水位情况下蓄量比沉降前增加了14%,;地面沉降后100年一遇洪水时,原调度方案不能满足滞洪要求,需改变原只启动前3区的调度原则,增加启动Ⅳ区滞洪,使得淹没面积较沉降前增加了14.5%,,洪灾损失较沉降前增加了22.1%,,增加了洪灾风险.

According to the comprehensive analysis of remote sensing data and bench mark data in different years in Dahuangbao detention basin,the annual average land subsidence has dropped from 20,mm（1989—2002）to 12,mm（2002—2010）,the total settlement is still large although it has already shown a downward trend.In order to improve the comprehensiveness of analysis,the influence of embankment settlement on detention basin is considered,and the result shows that the discharge capacity falls by 30,m^3/s as the embankment elevation drops by 100,mm,which will lead to an increase in inflow.The 2D flood routing mathematical model for Dahuangbao detention basin is established using the alternating direction implicit（ADI）method.The simulation results show that land subsidence has an effect on storage capacity,which increases by 14%, compared with that before land subsidence under the design water level.When there is a 100-year flood after land subsidence,the original dispatching plan cannot meet the requirement of flood detention,the original scheduling principle of only using the first three areas should be changed,and partition Ⅳ will be used to detain flood,which will increase the inundated area by 14.5% and the flood loss by 22.1%, compared with those before land subsidence,thus leading to the increased flood risk.