Document Type : Research Article
Authors
1
Department of Mathematics, Mahs.C. Islamic Azad University, Mahshahr, Iran
2
Department of Geography, Mahs.C. Islamic Azad University, Mahshahr, Iran
3
Department of Environment, El.C., Islamic Azad University, Tehran, Iran.
10.22059/ije.2026.411871.1908
Abstract
Objective: This study aimed to analyze the hydrological behavior of the Savadkouh watershed in Savadkouh County, simulate flood flow, and perform flood risk zoning using hydrological and hydraulic models, considering the region’s mountainous conditions, steep slopes, heavy rainfall, and extensive land use changes.
Method: Topographic data, land use maps, soil hydrological groups, and rainfall information were collected and processed. The Watershed Modeling System (WMS) model and the Soil Conservation Service (SCS) method were applied to estimate runoff curve number (CN), moisture retention capacity, runoff depth and volume, and flood hydrograph. Hydraulic flow simulation was then conducted using the Hydrologic Engineering Center’s River Analysis System (HEC-RAS) based on 21 river cross-sections. Finally, flood zoning and flow depth maps were generated.
Results: The findings indicated that topography, soil permeability, land use type, and rainfall intensity are the most influential factors in runoff generation and flood risk increase. The average curve number (CN) of the basin was estimated at approximately 78.3, reflecting a relatively high runoff potential. Areas with hydrological soil groups C and D, intensive agricultural lands, residential areas, and steep slopes showed the highest runoff volume and flood depth. Hydrographic analysis revealed a rapid watershed response, short concentration time, and high peak discharge, increasing the probability of flash floods. Flood zoning results were consistent with locations of previous flood events.
Conclusions: The study concludes that land use change and reduction of vegetation cover have significantly increased flood risk in the basin. Effective flood risk mitigation strategies include vegetation conservation, controlling development within floodplains, reforming land use management practices, and implementing comprehensive watershed management measures.
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