Soil cohesion was measured in the topsoil of 56 soil profiles. The lowest cohesion, 3 kPa, was detected in soils completely saturated with water. Soil cohesion model adaptation depends on many factors and is complex. We assumed a minimal cohesion of 3 kPa at critical state equilibrium all over the area, because failure is expected to occur while soils are saturated with water. Wu and Sidle 1995) used a similar cohesion value (2.5 kPa) within their slope stability model for steep forested basins