Flood Management Strategies in Indonesia: A Lesson Learned from Pepe River, Central Java

Floods occur every year and threaten communities worldwide. Indonesia is among the countries faced with this problem and still struggling to seek practical solutions to date. Further, as the country's centers of trade, business, and technology, the island of Java cannot even perform better in dealing with floods. To further understand possible damage and losses, this research investigated structural mitigation measures as part of flood management in the Pepe River, notably river channelization to increase hydraulic efficiency. For the analysis, it used HEC-RAS to observe the river capacity. Existing conditions revealed that the river could not accommodate the predicted floods based on the return periods derived from the synthetic unit hydrograph of Nakayasu. However, after running the mitigation scenario wherein hydraulic modification was applied, flood risk could be reduced by lowering the river water level. Based on the results, it can be concluded that Indonesia needs to pay more attention to other aspects: ecology, green infrastructure, and water governance, to achieve more effective flood mitigation measures because structural mitigation only provides a temporary solution.