基于SWMM模型的城市洪涝过程模拟及风险评估

SWMM-Based Urban Flood Modelling and Risk Evaluation

以SWMM模型作为研究基础,建立了西安市沣西新城区洪涝过程模型,对由暴雨强度公式和芝加哥降雨过程线合成的不同重现期、历时120 min、雨峰系数为0.4的降雨情景开展洪涝过程及其风险评估研究。计算结果表明:该区域设计的排水管网可抵御3年一遇暴雨,但高于此重现期的暴雨会出现不同程度的内涝;溢流最严重的节点在重现期为T=10年暴雨中最大积水深约0.20 m,对城市影响程度不大,但在T=20年暴雨中最大积水深可达0.56 m,可引起严重灾情。根据积水深度模拟结果,可初步判断出在T=20年暴雨过程的特定时段(75~105 min)内,积水会导致以溢流节点为中心10 m范围内的行人和车辆失稳。

Owing to the impacts of urbanization and climate change,urban floods become more and more serious,which is one of the urgent problems to be solved.Therefore,it is necessary to conduct flood inundation modeling and risk assessment in urban area.A coupled model on basis of SWMM has been proposed for predicting urban flooding in Fengxi New town,Xian.This model was used to simulate the process of urban flood routing and assess the corresponding flood risk under various rainstorm scenarios of different return periods with the duration of 2 hours and the rain peek coefficient of 0.4,which were designed by the rainstorm intensity formula and the Chicago rainfall hydrograph.These results show:the designed drainage network in the study area can withstand the rainstorm with a 3-year return occurrence,but for the rainstorm whose return period is higher than this frequency,different degrees of waterlogging would occur;the node with the most serious overflowing would have the maximum ponding depth of 0.20 m for the rainstorm with the frequency of T=10a,and it would cause a little influence on the city management.This node would have the maximum ponding depth of 0.56 m for the rainstorm with the frequency of T=20a,which would lead to severe urban flood disaster.According to the ponding water depth obtained from the simulation results,the evacuation information needs to be issued timely in the case of the rainstorm with the frequency of T=20a,and the ponding water can lead to instability of pedestrians and vehicles around the overflowing node with a 10 m radius during the rain period from 75 to 105 min.