The WCAMS, or Watershed Characterization and Management System is a suite of tools developed to enable resource managers to estimate the impacts of various land-use change scenarios on a regional or local scale. The basic unit of operation is a user-defined drainage area, which can be as small as 20 acres.

This defined area, often called a watershed, also called a basin, drainage or catchment area, is the area contributing surface runoff to an outlet point. This "watershed" boundary is determined by selection of the outlet point, and the process of defining the boundary of a watershed is known as watershed delineation, WD. Watershed delineation processing is the very first step of hydrological analysis, and the step was traditionally implemented using paper maps and field surveying.

Today the first step is done on our server using map layers precalculated from Digital Elevation Models.

After the catchment is calculated, the software compiles landuse, soil, and weather data for that area. The hydrologic impact of the combinations of soil and landuse types is calculated using the "curve number" process. (See powerpoit below for more info on this process.) "Hydrologic impact" includes the volume and chemistry of the water flowing across this landuse-soil combination into adjacent surface waters. Our model does not use subsurface flow, nor does it change the saturation of the soil for different seasons. Our model assumes all the rainfall runs evenly across the landscape into the stream, which is to say all the landuse is used, not just landuse on slopes or in channels.

We have created "Metadata" for the map layers we use here:

http://cobweb.ecn.purdue.edu/~caagis/metadata/lthia_layers.htm

We have created a FAQ, here: http://cobweb.ecn.purdue.edu/~caagis/metadata/LTHIA_OWL_FAQ.htm

and a series of short tutorial videos here: http://cobweb.ecn.purdue.edu/~caagis/LTHIA/WCAMS_tutorials.htm

and a Powerpoint(tm) to help the user of this site.

http://cobweb.ecn.purdue.edu/~theller/demos/LTHIA_2007_training.ppt

To start the session, click here or on the watershed picture

Watershed Delineation Program by Jin-Yong Choi, Tong Zhai, & Bernard A. Engel

Agricultural & Biological Engineering Department, Purdue University

 1146, ABE Building, West Lafayette, IN, 47907-1146

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