An Assessment of Nature-Based Solutions Water Infrastructure for Flood Risk Reduction in Unplanned Area

This study aimed to investigate the effectiveness of the Brigif Reservoir as a pioneering nature-based infrastructure solution for mitigating flood risk in the Kemang area, a significant business district in South Jakarta, and to provide a potential raw water supply for city parks. We employed coupled HEC-HMS and HEC-RAS 1D2D unsteady flow models to analyze rainfall-runoff and flood regimes before and after basin intervention in a rainfall scenario from January 2020. The flood model demonstrated highly satisfactory performance on the calibration results, as evidenced by an NSE value of 0.93 on a scale of 0 to 1. Flood risk was defined using the flood hazard, vulnerability, and capacity indices, and ArcGIS and QGIS were used to prepare and visualize the output after the model performance was qualified. The study revealed that the Brigif Reservoir could reduce the peak discharge of the January 2020 flood in the Kemang area by 19% while decreasing the risk of high-level flooding by 12%. The Brigif Reservoir, as a Nature-Based Solution (NBS) infrastructure, retains approximately 250,000 m³ of flood discharge, which can be utilized by the local government for watering gardens and as potential raw water for residents because it meets the national surface water quality standards in dry conditions and requires additional treatment during the wet season. The potential for groundwater recharge was estimated to be approximately 250 m³ and 6000 m³ for one hour and one day, respectively. For future studies, it is recommended to develop non-structural actions, such as a flood early warning system incorporating machine learning that could potentially support the operational performance of the NBS infrastructure. This study proposes the implementation of a series of sustainable infrastructure solutions, including rooftop storage, underground storage, and underground retention systems, at the building scale within each sub-catchment to mitigate flood risk levels in the Kemang region from high to acceptable levels. The findings of this research will be of significant value to the Water Resources Agency in evaluating the potential application of NBS infrastructure for flood mitigation and adaptation strategies and programs in response to the impacts of global climate change. Doi: 10.28991/CEJ-2025-011-05-07 Full Text: PDF