Probabilistic urban flood risk assessment of multi-sectoral economic losses due to levee overtopping

• Advanced flood models using detailed ground data predict water flow with high accuracy. • Maps show how rare flood events cause deeper water and wider spread in affected areas. • Economic damage estimates help officials plan protection for flood-prone communities. Flooding has been identified as one of the most frequent and economically disastrous natural hazards in Indonesia. However, most of the monetary loss due to flooding has been carried out using deterministic methods, which disregard the uncertainties associated with extreme precipitation and the exposure of multiple sectors. In addition, none of the existing research has considered the probabilistic flood risk associated with economic loss stemming from levee overtopping to multi-sectoral economic systems. Such a framework should be established to promote the resiliency of communities residing in riverine settings. This paper presents a probabilistic flood risk assessment of Citeureup Village in the Cikapundung River Basin, where floods caused by levee overtopping regularly occur during extreme rain events. First, a calibrated hydrological and hydraulic modeling is performed through 2D analysis using HEC-RAS, considering several rainfall hydrographs at different return periods. Model calibration is carried out using observed floods and local hydrological features. Spatial flood hazard maps are developed based on the evaluated hydrograph. Finally, flood risk associated with economic loss in various sectors, including residential, agricultural, and industrial regions, is evaluated by convolving the flood hazard map with the damage factor and the unit replacement cost associated with each sector. It is found that the events with higher return periods resulted in more serious inundation and considerably larger economic losses. In addition, the results presented in this study can identify key sectors that are affected by floods in the analyzed region. Therefore, this study can serve as a tool for decision-making and disaster countermeasures for the critical economic sectors in the region.