Problems and possibilities in urban drainage

Urban drainage problems in Canada will grow with increasing urbanization. In developing areas problems are related to increased volumes and rates of surface runoff; problems in developed areas are overloaded sewerage systems, combined sewer overflows, and urban surface water pollution. Research and demonstration programs in Canada and the United States are examining potential solutions to these problems. Rate and volume of storm water may be controlled by diversion of unwanted water or by storage. Controls on quantity include source controls, combined sewerage system modifications and operational changes, and treatment methods. Urban drainage models can simulate system behaviour and evaluate performance of alternative solutions. The three most generally useful models are STORM, Storm Water Management Model (SWMM), and the Illinois Urban Drainage Area Simulator (ILLUDAS). Development and application of models may be the most significant single result of urban drainage research and demonstration activities.