GIS-Based Multi-Criteria Flood Hazard Assessment in a Mountainous Basin: A Case Study of the Melamchi River, Nepal
DOI:
https://doi.org/10.64862/Keywords:
Flood Hazard Mapping, Disaster, Susceptibility, AHP- MCDAAbstract
Floods are among the most devastating hydro-meteorological hazards, causing major human and economic losses worldwide. Nepal’s rugged topography, monsoon-driven climate, active tectonics, and unregulated development heighten its vulnerability—particularly in mountainous river basins such as the Melamchi River Basin, Sindhupalchowk, which suffered severe flooding in 2021.
This study applies a GIS-based Multi-Criteria Decision Analysis (MCDA) integrated with Analytical Hierarchy Process (AHP) to assess flood risk in the basin. Ten key parameters—Elevation, Slope, Curvature, Precipitation, Land Use/Land Cover (LULC), Soil type, Distance to Roads (D2Road), Normalized Difference Vegetation Index (NDVI), Topographic Wetness Index (TWI), and Distance to River (D2River)—were derived from high-resolution datasets including SRTM, ALOS PALSAR, Sentinel-2, FAO soil maps, and WorldClim precipitation data (2012–2022).
Data were standardized, reclassified into susceptibility classes, and weighted via AHP, yielding a consistency ratio (CR) of 0.0835—within the acceptable range. A Weighted Linear Combination (WLC) method produced the Flood Hazard Index (FHI), categorizing the basin into five zones: Very Low, Low, Moderate, High, and Very High hazard. Precipitation (19.04%), TWI (15.38%), and D2River (15.12%) were the most influential factors. The steep elevation gradient (800–5,875 m) affects runoff, with low-lying areas prone to water accumulation. NDVI and LULC analyses indicated sparse vegetation and impervious surfaces increase vulnerability, while dense forest reduces it. Loamy and silty soils, combined with poorly drained road-adjacent and river-proximate areas, further elevate risk.About 38% of the basin lies in High to Very High hazard zones, with 26% in Moderate risk.The study identifies that the Melamchi River Basin contains extensive areas in low-lying, gently sloping terrain near river channels and poorly drained zones, which fall into High to Very High flood hazard categories, while moderately elevated and vegetated slopes exhibit lower vulnerability.
This study confirms that AHP-based MCDA effectively integrates environmental and anthropogenic factors for accurate flood hazard mapping, supporting resilient land use, infrastructure planning, and disaster risk reduction in mountainous watersheds.
References
Adhikari, D. P., & Koshimizu, S. (2005). Geological and geomorphological study of debris flows in the Kulekhani watershed, central Nepal. Journal of Nepal Geological Society, 31, 21–30.
Adhikari, B., Neupane, M., & Sthapit, B. (2019). Impact of anthropogenic activities on flood hazard in mountain watersheds. Journal of Hydrology and Meteorology, 15(1), 45–55.
Asian Development Bank. (2013). Melamchi Water Supply Project: Summary environmental impact assessment. https://www.adb.org/projects/documents/melamchi-water-supply-project-summary-eia
Beven, K. J., & Kirkby, M. J. (1979). A physically based, variable contributing area model of basin hydrology. Hydrological Sciences Bulletin, 24(1), 43–69.
Bhattarai, P., & Regmi, A. D. (2018). Flood risk mapping using geospatial techniques. Journal of Natural Disaster Science, 39(2), 23–31.
Correia, F. N., Fordham, M., & Saraiva, M. G. (1999). Flood hazard assessment and management: Interface with the public. Water International, 24(3), 108–116.
Dahal, R. K., & Hasegawa, S. (2008). Rainfall-induced landslides in Nepal. International Journal of Erosion Control Engineering, 1(1), 1–8.
Dhital, M. R., Khanal, N. R., & Thapa, K. B. (2021). The 2021 Melamchi disaster: Causes, impacts and implications. Journal of Nepal Geological Society, 62, 1–14.
Drăguţ, L., & Blaschke, T. (2006). Automated classification of landform elements using object-based image analysis. Geomorphology, 81(3–4), 330–344.
Duncan, J., Wright, S., Wong, K. S., & Brandon, T. (2003). Soil strength and slope stability. John Wiley & Sons.
FAO. (2003). Digital soil map of the world. Food and Agriculture Organization of the United Nations.
Farr, T. G., Rosen, P. A., Caro, E., Crippen, R., Duren, R., Hensley, S., ... & Alsdorf, D. (2007). The shuttle radar topography mission. Reviews of Geophysics, 45(2). https://doi.org/10.1029/2005RG000183
Fernandez, D. S., & Lutz, M. A. (2010). Urban flood hazard zoning in Tucumán Province, Argentina, using GIS and multicriteria decision analysis. Engineering Geology, 111(1–4), 90–98.
Fick, S. E., & Hijmans, R. J. (2017). WorldClim 2: New 1-km spatial resolution climate surfaces for global land areas. International Journal of Climatology, 37(12), 4302–4315.
Gigović, L., Pamučar, D., Božanić, D., & Ljubojević, S. (2017). Flood hazard mapping using GIS and multi-criteria analysis: A case study of Serbia. Water, 9(5), 360.
ICIMOD. (2021). Melamchi Flood Disaster 2021: Rapid assessment report. International Centre for Integrated Mountain Development.
Jenson, S. K., & Domingue, J. O. (1988). Extracting topographic structure from digital elevation data for geographic information system analysis. Photogrammetric Engineering and Remote Sensing, 54(11), 1593–1600.
Jiang, B., Claramunt, C., & Batty, M. (2012). Geometric accessibility and geographic information: Extending desktop GIS to space syntax. Computers, Environment and Urban Systems, 26(4), 353–369.
Lee, S., Kim, Y. S., Oh, H. J., & Park, I. (2017). Flood susceptibility mapping using frequency ratio, analytic hierarchy process, and logistics regression methods. Environmental Earth Sciences, 68(1), 1443–1454.
Malczewski, J. (1999). GIS and multicriteria decision analysis. Wiley.
Malczewski, J. (2006). GIS-based multicriteria decision analysis: A survey of the literature. International Journal of Geographical Information Science, 20(7), 703–726.
MoWS. (2022). Post-flood damage assessment of Melamchi Water Supply Project. Ministry of Water Supply, Government of Nepal.
Mustafa, A. A., Sulaiman, W. N. A., & Karim, O. A. (2005). Flood hazard assessment of the Klang River Basin, Malaysia. Environmental Geology, 48(8), 1113–1123.
Paudyal, D. R., Thapa, B. R., & Tuladhar, A. M. (2012). Urban growth modeling and flood risk assessment using GIS. Journal of Urban and Environmental Engineering, 6(1), 47–55.
Prasai, R., & Thapa, N. (2022). Land use change and its impact on flood risk in mountainous watersheds. Nepal Journal of Environmental Science, 10(2), 66–74.
Saaty, T. L. (1977). A scaling method for priorities in hierarchical structures. Journal of Mathematical Psychology, 15(3), 234–281.
Saaty, T. L. (1980). The analytic hierarchy process. McGraw-Hill.
Saaty, T. L., Vargas, L. G., & Forman, E. H. (2012). Models, methods, concepts & applications of the analytic hierarchy process. Springer Science & Business Media.
Senanayake, I. P., Welivitiya, W. D. D. P., & Nandalal, K. D. W. (2016). Flood risk assessment and mapping in urban environments: A case study of Colombo, Sri Lanka. ISPRS International Journal of Geo-Information, 5(5), 78.
Sharma, R., Thapa, M., & K. C., M. (2021). Topographical analysis for flood modeling in mountain basins. Journal of Hydrology and Meteorology, 14(1), 54–63.
Shrestha, S., Babel, M. S., & Maskey, S. (2020). Climate change impacts on water resources in the upper Blue Nile Basin, Ethiopia. International Journal of Climatology, 40(3), 1470–1488.
Tehrany, M. S., Pradhan, B., & Jebur, M. N. (2014). Flood susceptibility mapping using a novel ensemble approach based on support vector machine and frequency ratio. Geomatics, Natural Hazards and Risk, 5(3), 243–265.
UNDRR. (2019). Global assessment report on disaster risk reduction. United Nations Office for Disaster Risk Reduction.
World Bank. (2020). World Bank disaster risk management report: Flood resilience in South Asia. https://www.worldbank.org
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