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Flood hazard mapping and integrated mitigation measures for the Arau Watershed, Padang City
Last modified: 2022-11-15
Abstract
Cities growing in lowlands near or bordering the sea are frequently at risk of flooding. Padang, a coastal city in West Sumatra, is traversed by the Arau River, which forms a watershed with a parallel drainage pattern. This characteristic generates high flood discharge concentrated at points of confluence downstream, resulting in rapid flood responses. Learning from the history of repeated floods and considering the expected increase in rainfall due to climate change, this paper presents flood hazard analysis using a watershed approach and a design flood as the basis for mitigating flood impacts in the coastal city. The study built modeling scenarios that calculated design rainfall and inputted the probable maximum rain derived into the rational equation for quantifying flood peak discharge. The results were later compared with the river channel capacity (secondary data) to predict overflows and inundated areas. Afterward, the distribution of flooding, which indicated hazards, was spatially analyzed to determine suitable impact reduction. Finally, the model-based and government-regulated mitigation practices were compared and analyzed descriptively. Overall, the research was designed to (1) map flood hazards in the lower course of the Arau Watershed and (2) formulate integrated mitigation measures.