SWMM-CAT allows users to evaluate climate change impacts on stormwater runoff volume and quality, and to explore how the application of various low-impact development (LID) options can be used to alter these hydrological parameters. SWMM provides a spatial and temporal analysis of runoff quality and quantity by dividing basins into multiple sub-catchment areas and analyzing runoff at different time steps. It covers a variety of different drivers that can cause runoff in urban areas, including rainfall, snowmelt, and groundwater percolation, among others, and also allows for mapping and modeling of different sub-catchment drainage system components, including pipes, channels, diversion structures, storage and treatment facilities, and natural channels. These components allow users to examine relationships between total rainfall, runoff, and various routing options at a sub-catchment scale to effectively plan and design stormwater and sewer systems.