Also called the compound topographic index, the wetness index describes the effect of topography (slope and aspect) on the location and size of areas of water accumulation in soils. In its simplest form, the wetness index is calculated as: wi=ln (α/tan β), where α is upslope contributing area and β the local surface gradient. See Sulebak et al. (2000) Geografiska A 82, 1.
Subjects: Earth Sciences and Geography.