Integration of Nature-Based Solutions into Flood Defence for Sungai Damansara using Info Works Integrated Catchment Modelling

Abstract

In Malaysia, intense floods such as flash floods are characterized by rapidly rising water levels and sudden onset, often overwhelming flood defences and evacuation routes. The Sungai Damansara catchment in Selangor has experienced frequent and severe flooding despite conventional structural mitigation measures, including flood walls and detention ponds. Rapid urbanization in the region has reduced natural infiltration, increasing peak runoff and surface discharge. This study explores the use of Nature-Based Solutions (NBS), specifically Floodplain and Riparian Zone Restoration (Flood Resilient Redevelopment), to mitigate flooding. Critical factors such as water level and flow rate were assessed for their influence on flood severity and associated risks. A coupled 1D–2D hydrodynamic model was developed using InfoWorks Integrated Catchment Modelling (ICM) software to simulate flood behaviour under existing conditions and scenarios enhanced with NBS, flood walls, and pond modifications. Design storms with a 200-year Annual Recurrence Interval (ARI) were used to evaluate extreme flood impacts. Simulation results indicated that NBS reduced water levels by up to 12% and peak flow by up to 78% for a 200-year ARI event compared to existing conditions. In contrast, flood walls had minimal hydrologic impact, while pond modifications reduced water levels by only 4% and peak flow by 10%. These findings demonstrate that NBS can outperform conventional measures in flood attenuation while enhancing ecological resilience. The study highlights the potential of NBS to complement or even replace traditional hard infrastructure, supporting integrated and sustainable flood risk management strategies in rapidly urbanizing catchments.