A Learning and Decision Methodology for Drainage and Sanitation Improvement in Developing Cities

Abstract

In urban areas in the South drainage and sanitation systems in various states of development coexist. At a certain stage authorities have to take decisions concerning the transition from on-site to off-site systems or the unification (centralization) of the decentralized systems in their constituencies. A method is presented to support decisions about drainage and sanitation systems based on multi-criteria decision analysis in combination with stakeholder dialogues. This participatory methodology brings about a learning process in which experts and non-experts are enabled to connect local experience with systemic knowledge, in order to generate, assess and select sustainable drainage and sanitation solutions. The method is supported by a database which describes 58 drainage and sanitation options, assessment objectives, a screening aid and a performance matrix. The options are constructed on the basis of different water-using and reuse-oriented toilet types, the use/non-use of septic tanks, and different collection systems for stormwater and domestic waste water, which distinguish themselves by different environmental performance and the way the unwanted water is transported. Through application during workshops in Ho Chi Minh City (Vietnam) and Kampala (Uganda) insight was gained in the possibilities of the method and in items to be improved.