L-THIA Long-Term Hydrologic Impact Assessment Model ….provides relative estimates of change of runoff and non point source pollutants caused due to land use change.

Impervious cover and runoff... decreased groundwater recharge downstream flooding due to increased runoff rapid erosion of stream banks pollutants in runoff adversely affect aquatic life

Short-term impacts of land use change flooding property damage increased storm water drainage economic impacts

Long-term impacts of land use change Increase in surface water quantity Decrease in surface water quality Decreased groundwater recharge … eventually affecting municipal supplies Increased downstream flooding Adverse affect on aquatic life

Non-point Source (NPS) Pollution Originates from diffuse sources as a response to –Land use –Storm events Stormwater runoff from –Agricultural lands, construction sites, urban areas Long-term impacts –Storage (lake) loss from sediment deposition –Adverse effect of chemical pollutants

L-THIA Model An overview / screening model User friendly tool Does not require detailed data input Identifies need for more detailed modeling Provides "What-If" alternatives evaluation scenarios

Potential applications of L-THIA assess what can be done to minimize impact of development a criteria in the site selection process for land use change input parameter for land use zoning by planners and decision makers