Application of L-THIA Model in the Impact Assessment of Land use Change Effects on Water Resources

Land use changes have considerable effects on the environment and direct reduction of water resources and water quality are two of them. In the present study, the L-THIA model has been applied to model and evaluate the hydrologic effects of land use change. L-THIA model is a hydrological model that is available through L-THIA GIS / NPS extension in Arcview software. L-THIA gives long-term average annual runoff for a land use configuration based on actual long-term climate data, soils, and land-use data. While most hydrological models are complex, expensive and require a lot of data and time, L-THIA model can take advantage of its simplicity, availability and only needs low cost data. In the present study, this model has been described to evaluate the effects of land use change on water resources. The model has been used in many studies in different areas all of them showing increased depth and volume of runoff after conversion of natural to manmade features. We find the need for land use planning and management programs to careful inclusion of the effects of land use change on water systems. Through application of this model and prediction of future land use scenarios, we can predict the impacts on surface water and design land use so as to cause the least negative impacts on water resources.