Land use change has significant impact on the surface runoff process of a watershed. In this book, methodology is described to combine an empirical land use change model and an event scale, rainfall-runoff model to quantify the impacts of potential land use change on the storm-runoff generation in the Lai Nullah Basin. The HEC-HMS rainfall-runoff model was calibrated and validated for 5 storm events in the study area, and the results showed good consistency between the simulated and measured hydrographs at the outlet (Katarian Bridge) of the basin. The future land use scenario was forecasted based on Islamabad Master Plan and growth pattern. The calibrated HEC-HMS model was applied for these future land use scenarios to assess the potential land use impacts on the storm-runoff generation. The results indicated that the future land use as envisaged in the master plan is projected to increase the total runoff up to 100.0% as well as the peak discharge up to 83%. This book provide useful information for land use planner and manager and the methods applied can serve as a useful tool for future land use impact studies.