Developed by Dr. Bernard Engel (Purdue University)


The Long-Term Hydrologic Impact Assessment (L-THIA) model calculates the impact of land use changes on the hydrology of a watershed. The gauges display changes in Nitrogen, Phosphorus, Suspended Solids, Lead, Copper, and Zinc before and after land use changes are made. This gives the user the ability to manipulate land uses in various locations in the watershed and visualize the resulting impacts to water quality.


  • Draw and erase areas of differing land uses to understand the effect
  • Gauges displaying contaminant and nutrient loads as land uses are altered
  • Save and print maps or data for planning and decision-making

About the Model (9:33)

Additional Information


  1. Choi, J., Engel, B. A., Muthukrishnan, S., & Harbor, J. (2003). GIS based long term hydrologic impact evaluation for watershed urbanization. Journal of the American Water Resources Association, 39(3), 623-635. doi:10.1111/j.1752-1688.2003.tb03680.x
  2. Engel, B. A., Choi, J., Harbor, J., & Pandey, S. (2003). Web-based DSS for hydrologic impact evaluation of small watershed land use changes. Computers and Electronics in Agriculture, 39(3), 241-249. doi:10.1016/s0168-1699(03)00078-4
  3. Liu, Y., Bralts, V. F., & Engel, B. A. (2015). Evaluating the effectiveness of management practices on hydrology and water quality at watershed scale with a rainfall-runoff model. Science of the Total Environment, 511, 298-308. doi:10.1016/j.scitotenv.2014.12.077
  4. Liu, Y., Theller, L. O., Pijanowski, B. C., & Engel, B. A. (2016). Optimal selection and placement of green infrastructure to reduce impacts of land use change and climate change on hydrology and water quality: An application to the Trail Creek Watershed, Indiana. Science of the Total Environment, 553, 149-163. doi:10.1016/j.scitotenv.2016.02.116

Tool Screenshots


Contact Us

Technical Contact
Lydia Utley
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Telephone :(765) 494-3580

Mailing Address
195 Marsteller St.
West Lafayette, IN 47907


Program Contact
Kara Salazar
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Telephone :(765) 496-1070