Soil Erosion Susceptibility Assessment of the Seyhan River Basin Using Stream Power Index (SPI) and Topographic Wetness Index (TWI)

Year 2026, Volume: 8 Issue: 1 , 28 - 38 , 30.03.2026

Onur Güven , Ümit Yıldırım

https://izlik.org/JA52FY96MJ

Abstract

This study aims to identify soil erosion-sensitive areas in the Seyhan River Basin by jointly evaluating the Stream Power Index (SPI) and the Topographic Wetness Index (TWI). The analyses were conducted in a Geographic Information System (GIS) environment using topographic–hydrological parameters derived from a 30 m resolution Digital Elevation Model (DEM). SPI represents the erosive power of flowing water based on slope and flow accumulation, whereas TWI reflects the spatial distribution of water accumulation and soil saturation. The results indicate that high SPI values are concentrated in the middle and upper parts of the basin, where steep slopes and dense drainage networks prevail, highlighting areas with higher erosion susceptibility. In contrast, elevated TWI values are mainly observed in valley bottoms, low-slope areas, and basin outlet zones, indicating regions dominated by surface runoff and sediment accumulation processes. The combined interpretation of SPI and TWI maps enabled a clear spatial distinction between erosion- and deposition-dominated zones, revealing the strong topographic control on erosion dynamics across the basin. Unlike approaches that rely on subjective weighting or complex modeling, the proposed SPI–TWI-based framework offers a simple, objective, and data-efficient method for erosion susceptibility assessment, as it relies solely on DEM-derived topographic parameters without requiring additional soil, climate, land use, or field-based datasets, making it particularly suitable for data-scarce basins. The findings provide valuable insights for prioritizing soil conservation measures, land-use planning, and sustainable watershed management strategies in the Seyhan River Basin and similar Mediterranean environments.

Keywords

GIS-based modeling , Soil erosion , SPI , TWI , Seyhan River Basin

Ethical Statement

In the study, the authors declare that there is no violation of research and publication ethics.

Supporting Institution

This study received no external funding.

Thanks

AI–based tools were used during the preparation of this manuscript to assist with language refinement and readability. The tools did not contribute to the scientific analysis or conclusions, which remain entirely the responsibility of the author. This study received no external funding.

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