How GIS Supports Sustainable Urban Drainage Systems (S U D S) Another powerful way GIS supports SUDS is through hydrological modeling. By combining rainfall data, soil characteristics, slope, and land cover, GIS-based models can simulate how water behaves during different storm events. Planners can test scenarios such as moderate rain, extreme storms, or future climate conditions. These simulations help answer practical questions: Will a proposed rain garden reduce flooding downstream? How much