GUIDING THE DEVELOPMENT OF URBAN DRAINAGE SYSTEMS BY SUSTAINABILITY CRITERIA

The development of urban drainage towards sustainability is discussed, primarily on the basis of case studies of mature urban drainage syste ms. Typical problems and a series of possible measures to enhance the systems performance are evaluated. We consider CSOs, receiving water q uality, and decreasing ground water levels as actual problems. We dist inguish between improvement strategies which focus on the technical sy stem itself (e.g. storm water retention tanks, real time control) and strategies which may be described either as source control or as impro ving the resilience of the receiving water. Their efficiency is evalua ted on the basis of shea term 'conventional' criteria and by means of the following sustainability criteria: systems definition (time and sp ace constants), resource efficiency and degrees of freedom. Surprising ly, the rating of the different strategies according to the two sets o f criteria are quite close: In both cases, the measures which do not n arrowly focus an the technical system obtain the better score. (C) 199 7 IWAQ. Published by Elsevier Science Ltd.