Compound Topographic Index/Catchment Wetness Index from DTM data

Discussion created by kellyw82 on Nov 30, 2011
Hi folks,

I know there has been some discussion on the forums about this already but I'm really needing to get some expert advice.

We have DTM data in .asc format for a proposed development site and I need to be able to calculate the CTI/CWI to determine areas of the site that are likely to become saturated.  The resolution of the elevation data is 50m so I'm aware that the outputs may not as accurate as required but the development is at the planning stage so we only need to show the general areas.

From previous discussions on the forum it looks like the CTI could be calucated using the Raster Calculator but i've not got much experience using this tool so I would not know where to begin.

If Raster Calculator cannot be used can anyone please direct me to a tool or script that I can download?

We're using ArcGIS 10 with an ArcEditor license.  We also have a license for Spatial Analyst

Many thanks,