TITLE:
Assessment of Soil Erodibility in the Mont Rolland Dam and Lac de Guiers Watersheds (Senegal)
AUTHORS:
Samba Bousso, Mory Coulibaly, Saïdou Ndao, Makhlay Ba
KEYWORDS:
Soil Erodibility Factor K, Soil Loss, Water Erosion
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.18 No.10,
October
23,
2026
ABSTRACT: Water erosion and associated sedimentation threaten the sustainability of reservoirs and surface water resources in Senegal. Because soil-loss estimates using USLE, RUSLE and USPED depend directly on the soil erodibility factor K, the selected K formulation can substantially affect model outputs. This study compares six approaches—Wischmeier, EPIC, Römkens-Renard, Torri- Poesen-Borselli, Auerswald et al., and the Römkens-Renard relationship using a Shirazi-derived geometric mean diameter—using 20 samples from the Mont Rolland Dam watershed and 28 samples from the Lac de Guiers watershed. With the updated calculations, mean K at Mont Rolland ranges from 0.01014 for the Römkens-Renard relationship with Shirazi-derived Dg to 0.05007 for Auerswald et al.; EPIC and Wischmeier yield similar means (0.03639 and 0.03618, respectively). At Lac de Guiers, mean K ranges from 0.01079 for Römkens-Renard to 0.02274 for the Shirazi-derived Dg implementation; Torri-Poesen-Borselli gives 0.01291 and has the lowest relative dispersion (CV = 6.09%). Wischmeier and Auerswald remain strongly correlated in both watersheds (r = 0.963 at Mont Rolland and r = 0.988 at Lac de Guiers), whereas several other inter-method relationships differ between sites. The updated results confirm that K is strongly method-dependent and support multi-method sensitivity analysis and local validation before selecting K for erosion modelling.