NPS pollution is currently a major environmental problem that effects water quality in wetlands, lakes, rivers, oceans, and ground water resources. NPS pollution occurs when runoff from rainfall events transports man-made and natural pollutants and deposits them into these water resources. The Long Term Hydrologic Impact Assessment (L-THIA) model was used in a Geographic Information System (GIS) to estimate NPS pollution and runoff in the Kokomo, Indiana area. L-THIA was developed to provide estimates of runoff and NPS pollution based upon land use changes. It uses hydrologic soil group, land use and long-term weather data in the estimation. It is intended to provide awareness of possible long-term effects of land use changes, rather than predictingwhat will result in a specific year. For this project, three land use data sets were examined. These included USGS (1970's), GAP (early 1990's), and EROS (mid 1990's) land use data sets. The hydrologic soil group data is from a STATSGO data set. The weather information came from the www site http://danpatch.ecn.purdue.edu/~sprawl/LTHIA5/. The purpose of this project was to examine changes in runoff and NPS pollution due to the transition from agricultural to urban land use. The NPS pollutants considered included Nitrogen and Lead. The intent was to evaluate differences based upon urban development and other land use changes in the region.
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