The L-THIA Root River Watershed Management Tool


This collaboration between Purdue University and the

Wisconsin Department of Natural Resources

provides tools to perform environmental analyses within

the Lower Root River watershed.

Tools are available to evaluate how land cover change scenarios impact the estimates of non-point source runoff, prioritize sub-basins by erosion and sediment loading, explore low impact development (LID) options, and map-browsing.

To access the specific tools follow the links below.


Map Interface for Lower Root River Hydrologic Impact Assessment: L-THIA.

(No longer in service.)

Help Movie for this tool


LTHIA Low Impact Development Spreadsheet. (A simple version with no map input.)



What is LTHIA:

Community planners, developers and citizens of a community should be aware of the long-term impacts of landuse change on their environmental resources. LTHIA, Long-Term Hydrologic Impact Assessment, is designed to help these people to quantify the impact of land use change on the quantity and quality of their water. This tool uses the land use and a soil characteristic from the user along with thirty years of precipitation data to determine the average impact that a particular land use change or set of changes will have on both the annual runoff and the average amount of several non-point source pollutants. For those unfamiliar with the hydrologic (water related) impacts of land use change this tool along with the supporting documents will hopefully give the user enough information to start asking questions about land use changes in their area.

[ How LTHIA works ]



Spreadsheet and OWL LTHIA

There are several input screens for Standard L-THIA (using TR-55 curve numbers), which are available below.

For residents of EPA Region 5 states, there also is a GIS version which automatically categorizes landuse and soil based on your location. [ Online watershed delineation (OWL) and LTHIA ]

For those new to L-THIA and land use planning Basic Input is a good place to start. There are eight choices for land use types which most land uses fall into. For those familiar with land use planning terms or need to describe a custom land use, Detailed Input gives more land use options. The fourteen choices for land uses includes 6 lot sizes for residential housing and an option to define a custom land use. After using the Basic Input for a few analyses, a user would be able to use the Detailed Input. The advanced versionof this allows customizing EMCs as well.

[ Basic Input LTHIA Spreadsheet ]



Fact Sheet for L-THIA

Powerpoint(tm) for L-THIA workshop in Swan Creek , Ohio

Fact Sheet for LID-LTHIA

Powerpoint(tm) for LID-LTHIA workshop in Swan Creek, Ohio

Tutorial for hands-on training at a workshop.


Root River Management System Map Page

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