Flood hazard assessment in Kuala Langsa village, Langsa city, Aceh Province-Indonesia

Abstract

This study evaluates the flood hazard index in Kuala Langsa Village, Langsa City, Aceh, a region prone to frequent flooding due to its low-lying coastal location in eastern Aceh. It serves as a crucial link between North Sumatra and Aceh provinces. The area's significance underscores the importance of understanding and mitigating flood risks. By utilizing the coupled 1D/2D Hydraulic model, flood hazards are accurately predicted and mapped. The field data collection (as calibration) measures the maximum tidal water level based on information from residents affected by flooding on the land surface under their houses. Hydrological conditions during the December 2017 flood event are simulated using HEC-HMS. Hydraulic conditions are evaluated using HEC-RAS 6.4.1. The research aims to assess the flood hazard index in Kuala Langsa Village under spring tide conditions, considering variations in base flow and flood flow with return periods of 2 and 50 years upstream. The main results show that an FHI >2.62 (high) covers an area of 169.74 ha, 2.62 > FHI >2.23 (moderate) encompasses 172.60 ha, and FHI <2.23 (low) accounts for 222.32 ha. During the Q50 upstream flood, there was an increase in flood extent: low by 61.20 %, medium by 25.32 %, and high by 5.57 %. These findings deepen our understanding of estuary flood mechanisms and emphasize the importance of developing more effective adaptation strategies to reduce flood risks in the future.

Keywords

• Flood hazard index
• Tidal propagation
• Hydrological
• Hydraulic 1D/2D
• Adaptation calibration
• Kuala Langsa village