Optimal Planning for Urban Storm Drainage Systems

A watershed in an urban area may be partitioned into subbasins, each of which is a tributary to a downstream subbasin or to a receiving water body. The planning of a storm drainage system for such a watershed according to the requirements of Section 208, PL 92-500, can be efficiently accomplished by coordination of the interactions among the subbasins. A model for these interactions is presented and implemented in the urban storm drainage planning model URBDRAIN. The planning variables in the model are maximum conveying capacities of the drainage network, placement and size of detention storage facilities, and size of a central treatment facility. A two-level optimization solution procedure is shown which provides minimal-cost values for the planning variables. An example application is shown for a medium size community in Indiana.