Comprehensive Urban Stormwater System Modeling and Communications for Sustainable Urban Flood Management in Complex Plain-Escarpment Terrain

In the paper, considerations and approaches used for comprehensive urban stormwater system modeling and design for complex plain-escarpment terrain where there is potential for the system to be affected by flows from other high-steep hilly areas would be presented. Analyses of the hydrological and hydraulic modeling results and importance of coordination with pertinent agencies/public with its outcome, and support to the decision makers in formulating sustainable solution options for urban flooding problem and prioritizing the actions would be discussed. Serving the public and solving stormwater problems are the prime objective of the city engineers/planners’ decisions and actions. Managing stormwater system in densely populated foot-escarpment urban plain efficiently and effectively is complex and challenging process compared to other plain lands. There are considerable uncertainty and risks. The system designed considering design events may fail and results devastating flood due to certain reasons. Selection of the Design Event as well as consideration of all potential runoff sources, and operational and maintenance issues are crucial for effective management of urban flooding especially in areas located at the foot of the escarpment. The local storm drainage system might be affected considerably by the flows coming from higher elevation terrain or diversion of flows from other sub-catchments as a result of transitional conveyance blockage or limiting capacity exceedance. For the system to be sustainable, considerations of such potential risks and uncertainty must be assessed and taken into account comprehensively during planning and design phases. This paper would provide an insight in to the critical flooding issues and planning/design considerations. Analyses and results would be an important element in realizing the need for holistic investigations and prioritizing remedial works.