Optimal design and real time control of the integrated urban run-off system

Traditional design of urban run-off systems is based on fixed rules with respect to the points of demarcation between the three systems involved: the sewer system, the treatment plant and the receiving water. An alternative to fixed rules is to model the total system. There is still uncertainty with respect to a more rational formulation of demands on the performance of combined sewer overflows and the performance of separate drainage outlets during rain. There are two approaches to management: The prediction-design approach: models play an essential role in the prediction of performance and evaluation of competing alternatives for design. However, the complexity of these systems is such that the parameters associated with pollution are hardly identifiable on the basis of reasonable monitoring programmes. The empirical-iterative approach: structures are built on simplified assumptions and their performance is evaluated. If inadequate, improvements are made by another trial on an empirical basis. When monitoring has proven the performance to be inadequate, improvements can be achieved by real time control of the whole system, which combines the two approaches. Due to the complexity of the real system, the experience is that simplicity and on-line adaptation are essential features of the real time control system.