Representation and Evaluation of Low Impact Development Practices with L-THIA-LID: An Example for Site Planning

A computational framework was developed to represent, evaluate, and report the effectiveness of low impact development practices using the Long-Term Hydrologic Impact Assessment-Low Impact Development (L-THIA-LID) model. This framework consists of a four-step methodology to characterize the impacts of LID practices on runoff and pollutant loading using modified Curve Number (CN) values. The methodology was demonstrated in a case study of a residential subdivision in Lafayette, Indiana. The LID practices represented in this study are commonly used to mitigate hydrologic impacts of urbanization. Simulation results showed that water sensitive design principles could bring post-developed hydrology to a level comparable to that of pre-development. Implementation of LID practices should be carefully planned with preliminary studies and optimization techniques to attain intended goals. The methodology outlined in this study can be utilized within other computational models that support simulation of LID practices with the CN approach to assess the beneficial uses of these practices.