ESRI ArcView GIS software version 3.1 to 3.3 and its Spatial Analyst 1.0 or 2.0 extension are required.  Visit ESRI online at http://www.esri.com for more information about their GIS products.

See the links below for additional details: 

L-THIA GIS extension manual in pdf format

Preparing L-THIA rainfall input data (Word document)

L-THIA GIS extension software zip file

Sample data set for L-THIA GIS
 

Obtaining L-THIA Rainfall Input Data from the WWW Version 

Rainfall data in the format required by the L-THIA GIS tool is automatically created from a national database when you run WWW L-THIA. Using the state and county you provided, a text file is built from a datbase of 30 years of weather observations.

You can download this file to use with your GIS version of L-THIA on your PC. Begin by using the L-THIA WWW tool to create the runoff file.

Run the online version,use the "input" option to setup and make an L-THIA run for the county(s) of interest. Note, you will need to provide an area for at least one land use and soil combination in the form for Current Year. The rainfall data in L-THIA format for the state and county you select can be downloaded by following the link on the results page that says:  [ RAINFALL DATA ].