NEW APPROACH FOR OPTIMIZATION OF URBAN DRAINAGE SYSTEMS

A new approach for the optimization of urban drainage systems including the optimal selection of layout using the searching direction method and the optimal design of a given layout by discrete differential dynamic programming (DDDP) is developed and applied to a typical field study. It is found that the inclusion of such hydraulic factors as flow rate, the sizes and gradients of pipes, and the effect of on-line pumping stations into consideration, is very important in urban drainage systems layout selection. Also, the optimization of urban drainage systems including optimal layout selection can achieve much greater construction cost savings than that without the inclusion of layout optimization. It has also been demonstrated that the minimum buried depth design is not the global optimum design; instead, the global optimum design is the alternative of the optimal balance among the buried depth and the number and locations of on-line pumping stations. © ASCE.