WMS:Drainage Module

A primary use of WMS is to automatically delineate watershed, stream, and sub-basin boundaries from digital elevation sources such as TINs and DEMs. The drainage module includes all of the commands necessary to perform the automated delineations in preparation of running one of the hydrologic models.

While delineation can be performed using either DEMs or TINs, it is generally easier to use DEMs. In general the DEM method is simpler and more repeatable because of the uniform nature of a DEM data structure. When inadequate elevation resolution is available (i.e. many urban ares) then the feature object method of delineation should be considered.

Some basic guidelines might be:

1. DEMs are better for larger, rural watersheds
2. TINs might be more appropriate for smaller, urban areas with adequate resolution
3. The feature object method works well if no elevation data exist, or if the resolution of the elevation data is not adequate.

Since a DEM or TIN delineation can be converted to feature objects you may want to consider modifying an initial delineation with an elevation source manually with the feature objects. However, you must realize that some of the parameters computed from the elevation data will be compromised when manual adjustments are made with the feature objects. Be careful and understand what/why you are making modifications.

Related Topics

• Watershed Delineation with DEMs
• Watershed Delineation with TINs
• Watershed Delienation with Feature Objects
• DEMs
• TINs