Hi, all.

I'm trying to calculate Topographic Wetness Index with ArcGIS.

I was wondering how exactly is catchment slope calculated in Catchment Area module (parallel)?

I'm worried that I'm using wrong type of slope when executing topographic wetness module. Most of the literature related to TWI express TWI as Ln(a/tanB) where a is the spesific catchment area and tanB is the local slope. How does catchment slope, calculated here, correspond to this?