Interpreting Model Results

L-THIA results can be used to change land use based on soil type to minimize impact. The same land use located on different hydrologic soil types has different impacts. Because the amount of runoff generated by different land uses is a function of the hydrologic soil type and the land use, relocating land uses based on the hydrologic soil type can in some cases significantly reduce the long-term impact of the development.

Locating land uses that generate large amounts of runoff (eg. commercial) on soils that have naturally low infiltration rates (Hydrologic Soil Group D) reduces the hydrologic impact of the land use change. Covering soils that already don't soak up much water with impervious surface produces much less impact than covering well-drained soils with an impervious surface.

Various land use change scenarios and the corresponding change in runoff and Non Point Source (NPS) pollutants have been discussed here to assist the users to interpret model results.

• Agricultural land to low density residential : why does the runoff decrease?
• Forest to high density residential
• Commercial to high density residential
• Industrial to high density residential
• Agricultural land to commercial use
• Grass/pasture to high density residential