Failure of drainage systems leads to urban flooding; therefore, structural measures such as the installation of additional drainage facilities, including pump stations and detention reservoirs, have been adopted in the past to prevent and mitigate urban flooding. These measures, however, are costly and time consuming. To maximize flood mitigation efficiency, it is essential to also implement non-structural measures such as effective operation of drainage facilities. In this study, we propose a new cooperative operation scheme for urban drainage systems that involves linking centralized reservoir (CR) and decentralized reservoir (DR) operations by sharing water level information at monitoring nodes. Additionally, we develop a resilience index to assess the system's ability to mitigate, restore, and recover from inundation (i.e., failure). Most results show that flood reduction and resilience in cooperative operations are better than the current operation. However, the results of CR operation for 2010 are worse than the current operation at high monitoring node levels (1.4 m–1.5 m), and the results of DR operation for 2011 are worse than the current operation at low monitoring node levels (0.8 m–0.9 m). All results related to flood reduction and resilience in cooperative operation are superior to the current operation.

The individual and combined effects of structural and nonstructural measures on urban drainage system resilience were investigated in this study. The resilience of an urban drainage system is the system’s ability to recover from flooding or inundation damage. A novel pump operating method is proposed in this paper as a nonstructural measure, while expansion of the discharge pump capacity is considered to be a structural measure. The proposed method is demonstrated by application to the Daerim sewer network in Seoul, Korea, which has a discharge pump located in the detention reservoir at the center of the study network. The results show that less flooding is predicted with the new operating method than with the current operating method. Additionally, the new operating method, in conjunction with a pump capacity reflecting the inflow into the detention reservoir, yields stable results in most operating scenarios. The results of the resilience analysis illustrate that the new operating method applied in conjunction with sufficient pump capacity is more effective than the current operating method.