Civil Engineering and Architecture Vol. 13(6), pp. 4534 - 4545
DOI: 10.13189/cea.2025.130629
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Assessing the Performance of HEC-RAS 2D for Flash Flood Simulation in Mountainous Rural Eco-Tourism Area of Kampung Melangkap, Malaysia

Rosdianah Ramli ¹, Janice Lynn Ayog ^1,2,*, Ejria Saleh ^2,3, Mohammad Radzif Taharin ^1
1 Faculty of Engineering, Universiti Malaysia Sabah, Malaysia
² Natural Disaster Research Centre, Universiti Malaysia Sabah, Malaysia
³ Borneo Marine Research Institute, Universiti Malaysia Sabah, Malaysia

ABSTRACT

Flooding presents significant risks to rural communities, particularly those dependent on eco-tourism. While HEC-RAS 2D hydrodynamic modelling is widely applied in urban and lowland areas, limited research has evaluated its performance in rural, mountainous terrains where infrastructure and flood vulnerability intersect. This study addresses that gap by assessing the suitability of HEC-RAS 2D for simulating a flash flood event in December 2022 in Kampung Melangkap, Sabah, Malaysia. The model integrated river discharge and water level data with high-resolution digital surface models (DSM) generated through drone surveys. Three governing equations available in HEC-RAS - Diffusive Wave (DW), Shallow Water Eulerian-Lagrangian Method (SW-ELM), and Shallow Water Local Inertia Approximation (SW-LIA) - were tested using two computational grid sizes (20 m and 25 m). Model validation was conducted using observed flood depths and interviews with local communities from the most affected areas. The SW-ELM model with a 25 m computational grid produced the most accurate flood depth and extent simulations, with the smallest deviation from observed data. Among the tested configurations, it also balanced accuracy and computational efficiency, making it the most suitable option for flood modelling in the study area. These findings support the use of HEC-RAS 2D as a practical tool for flood risk assessment in rural eco-tourism regions.

KEYWORDS
HEC-RAS, 2D Flood Modelling, Rural Eco-Tourism, Shallow Water Equations, Diffusive Wave

Cite This Paper in IEEE or APA Citation Styles
(a). IEEE Format:
[1] Rosdianah Ramli , Janice Lynn Ayog , Ejria Saleh , Mohammad Radzif Taharin , "Assessing the Performance of HEC-RAS 2D for Flash Flood Simulation in Mountainous Rural Eco-Tourism Area of Kampung Melangkap, Malaysia," Civil Engineering and Architecture, Vol. 13, No. 6, pp. 4534 - 4545, 2025. DOI: 10.13189/cea.2025.130629.

(b). APA Format:
Rosdianah Ramli , Janice Lynn Ayog , Ejria Saleh , Mohammad Radzif Taharin (2025). Assessing the Performance of HEC-RAS 2D for Flash Flood Simulation in Mountainous Rural Eco-Tourism Area of Kampung Melangkap, Malaysia. Civil Engineering and Architecture, 13(6), 4534 - 4545. DOI: 10.13189/cea.2025.130629.