Analysis of drainage capacity in Xicheng district, Beijing with InfoWorks ICM

To evaluate flood control and drainage capacity in Xicheng district, Beijing, a refined flood control and drainage model is constructed with InfoWorks ICM． Simulation for peak flood discharge and total flood volume show error ranges of−16.7%~19.1% and −13.2%~6.9% respectively． Drainage capacity of pipelines and flood conveyance capacity of rivers under different rainfall durations and patterns are analyzed, and causes of urban flooding are diagnosed． Up to 41% of the pipeline network in Xicheng district has drainage capacity below 1-year return period, indicating rather poor drainage capacity． Maximum water level in downstream section of West Moat River under the 100-year return period is approximately 0.681 meters below embankment, indicating a potential safety risk． In upstream section of the North Moat River, maximum water level under the 100-year return period is about 0.60 meters, which exceeds the warning water level for that river section． Under a long-duration (24 hours) rainfall scenario with a 100-year return period, maximum water depth of urban flooding in Xicheng district reaches 1.710 meters． Therefore flood and drainage hazards in Xicheng district are primarily concentrated in areas with old houses, aging residential buildings, in shantytowns and mixed-use zones, which require focused attention． These findings will provide critical data support for flood and waterlogging management, and pipeline upgrades in Xicheng district． By integrating distribution of underground spaces and waterlogging points, these data provide ground for development of emergency plans for dual-use floodwater storage and retention spaces．