*Article* **Flood Reduction in Urban Drainage Systems: Cooperative Operation of Centralized and Decentralized Reservoirs**

#### **Eui Hoon Lee 1, Yong Sik Lee 1, Jin Gul Joo 2, Donghwi Jung 3 and Joong Hoon Kim 1,\***


Academic Editor: Helena Margarida Ramos Received: 5 July 2016; Accepted: 17 October 2016; Published: 22 October 2016

**Abstract:** 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.

**Keywords:** urban flooding; centralized reservoir; decentralized reservoir; cooperative operation
