Enhancement of Flood Hazard Assessment through Parameters Modification: A Case Study of the Sikambing Watershed

Abstrak

This study focuses on enhancing the flood hazard assessment parameters in
Indonesia, particularly within the framework established by the National Disaster
Management Agency (NDMA) of the Republic of Indonesia. Given the
multifaceted nature of flood hazards, influenced by factors such as land cover
change, climate change, and the failure of flood control structures, it is essential
to adopt a more comprehensive approach to flood hazard assessment. The research
was conducted in the Sikambing Watershed in Medan City, North Sumatra
Province, an area that has experienced 12 significant flood events affecting over
13,000 individuals between 2020 and 2024. To improve the flood hazard
assessment, this study employs a quantitative method where hydrological and
hydraulic analyses serve as the empirical foundation, and flood hazard mapping
is carried out by modifying existing parameters to incorporate flood depth (d),
flow depth and velocity (dv), and flood duration (T). Additionally, a comparison
is made with the flood hazard map based on NDMA parameters to analyze the
changes in hazard classification. The resulting flood hazard map indicates a total
inundated area of 227.65 hectares; however, the use of different parameters results
in significant changes in the proportions of each hazard class. While the low
classification dominates both maps, there is an increase in the inundated area
classified as medium, covering 17.43 hectares, compared to only 3.25 hectares for
the medium hazard classification in the NDMA-based flood hazard map. These
results demonstrate that parameter modification provides a more comprehensive
picture of flood hazard assessment. This research is expected to contribute to
disaster mitigation planning, evacuation strategies and the development of more
effective flood control infrastructure.