基于SWMM模型的城市已建区排水防涝提标改造途径探讨

DISCUSSION ON PATHWAYS FOR CAPACITY UPGRADING OF STORMWATER DRAINAGE AND FLOODING ALLEVIATION IN DEVELOPED URBAN AREAS BASED ON SWMM

随着城镇化建设高质量发展,城市排水防涝标准也在逐渐提高,因此,如何实施已建区排水系统的提标改造,是城市有机更新重要建设内容之一。以北京某已建区域为研究对象,提出了针对排水系统的排水能力和内涝防治标准GB 50014—2021《室外排水设计标准》统筹提标改造的方案,并借助于SWMM模型进行了方案优化评估。结果表明:通过海绵城市建设,在80%年径流总量控制率条件下,现状管网的排水能力可由1年一遇提标至2年一遇。在上述方案基础上,通过模拟评估内涝防治重现期(P=20 a)条件下雨水管网的过载情况,进一步提出并比较了调蓄池集中布置和分散布置2种方案,模拟结果表明:调蓄池末端集中布置无法解决上游区域管网的冒溢问题,而调蓄池分散式布置,可有效消除现状冒溢点,实现现状区域的内涝防治标准提高至20年一遇目标。因此,在已建区排水防涝提标改造过程中,根据场地空间条件,可优先考虑采用海绵城市建设与调蓄池分散式布置相结合的方式实现排水防涝提标改造目标。

With the high-quality development of urbanization,the standard of urban stormwater drainage and flooding alleviation are gradually increasing,therefore,how to realize the upgrade of stormwater drainage systems in developed areas is one of the important aspects of urban renewal.Taking a post-development area in Beijing as the research object,the pathways for upgrading the capacity of stormwater drainage system and the standard of flooding alleviation according to the revised Standard for the Design of Outdoor Wastewater Engineering(GB 50014—2021)were proposed and evaluated by SWMM.The results showed that,through the sponge city construction,the capacity of the existing stormwater drainage pipe network could be improved to 2-year return periods from 1-year,when the volume capture ratio of annual rainfall was 80%.On basis of sponge city construction,the operation of the stormwater drainage pipe was evaluated under the flooding alleviation standard of 20-year’s return periods,then the centralized and decentralized distribution ways of detention tanks were further proposed and compared.The simulation results showed that the centralized distribution of detention tanks,which located nearby the outlet of the stormwater drainage pipe,couldn’t alleviate the overflow from the drainage pipes in the upstream area,while the decentralized distribution of detention tanks could effectively eliminate the overflow from the drainage pipes in the upstream area,and upgrading the flooding alleviation capacity to 20-years’s return period.Therefore,according to site conditions,the optimal pathways to upgrading the capacity of stormwater drainage were sponge city construction,and upgrading the standard of flooding defense was the decentralized distribution of detention tanks in urban post-development areas.