沿海城市台风暴雨时空变化致涝特征模拟
Characteristics of urban waterlogging induced by spatiotemporal variations of typhoon rainfall in a coastal city
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摘要: 为探明台风暴雨时空变化对中国沿海城市内涝过程的影响, 应用地表水及其伴随输移过程数值模型, 以中国沿海城市宁波中心商贸商务区为研究对象, 进行多种移动台风降雨情景和静止台风降雨情景下的城市内涝研究。结果表明: ① 不同移动方向下的降雨会导致内涝监测点积水时间滞后, 向正西方向及西北方向移动时, 积水时间滞后0~0.5 h; 向正北方向移动时, 积水时间滞后1.5 h; 向北偏东30°方向移动时, 积水时间滞后1.5~2 h。② 在92%的模拟工况下降雨的移动会削减积水量和积水深度, 水深峰值最大削减率达4.46%; 降雨重现期从5 a增大到50 a时, 积水水深峰值削减率从0.49%下降到0.10%。③ 双峰型降雨与单峰型降雨对城市内涝积水的影响规律相似, 但前者的影响作用更小。因此, 在受台风暴雨侵袭的城市区域, 防灾减灾部门应考虑台风暴雨的时空移动特征, 进一步提高城市抗洪能力, 减少灾害损失。Abstract: To investigate the impact of spatiotemporal variations in typhoon-induced rainfall on the processes of urban waterlogging in coastal cities of China, a numerical model of surface water dynamics and its associated transport processes was applied. The central business district of Ningbo, a coastal city in China, was selected as the study area. The scope of this research encompassed a comprehensive examination of urban waterlogging under various scenarios, including conditions featuring both moving typhoon-induced rainfall and stationary typhoon-induced rainfall. The findings of this study are as follows : ① Rainfall moving in different directions leads to a delayed accumulation of water at waterlogging monitoring sites. The delay ranges from 0 to 0.5 hours when the rainfall moves directly westward or northwestward, 1.5 hours when moving directly northward, and 1.5 to 2 hours when moving in a direction 30 degrees east of north. ② In 92% of the simulated scenarios, the movement of rainfall results in a reduction in both the volume and depth of water accumulation. The maximum reduction rate of peak water depth reaches 4.46%. As the return period of rainfall increases from 5 a to 50 a, the reduction rate of peak water depth decreases from 0.49% to 0.10%. ③ The impact patterns of bimodal and unimodal rainfall on urban waterlogging are similar, but the former has a comparatively lesser impact. Therefore, in cities affected by typhoon-induced rainfall, the disaster prevention and mitigation ministry should give special consideration to the spatiotemporal movement characteristics of the typhoon-induced rainfall. This approach is crucial for further enhancing urban flood resilience and mitigating disaster losses.