Urban Drainage Systems: Evolution of Problems

The practice of urban drainage has been traced back to some of the earliest recorded histories of humankind. The expeditious conveyance of stormwater from urbanized areas was motivated primarily by reasons of convenience and the reduction of ̄ood damage potential. The removal of domestic wastes from households using waterborne conveyances was also found to be convenient. Such practices to improve the quality of urban life, however, have resulted in other problems, such as arti®cially induced ̄ooding, increased erosion, and environmental degradation stemming from the pollution of receiving waters. As a result, attention has focused on the comprehensive management of urban drainage systems, which includes, in addition to the ancient use of conveyances such as channels and pipes, the implementation of storage and treatment facilities as well as the real-time control of entire systems. The objective of this practice, is commonly referred to as stormwater management, is to intelligently utilize components of drainage systems in a manner that will improve the quality of urban life while protecting the environment in a cost-effective manner. To facilitate the effective management of these inherently complex combinations of natural elements and engineering works, mathematical modeling is often employed to better understand system behavior and performance which in turn leads to better engineering and management decisions. This book concentrates on the mathematical modeling of urban drainage systems, particularly for planning-level decision analyses. In the present chapter we outline the problems, both past and present, related to drainage system design practices. It is fundamentally important for engineers