Urban water systems, demand management and sustainable development

Abstract

This thesis is about urban water demand management and its relationship to planning in the context of sustainable development.

A theory of the development of economic systems as dissipative, self-organizing systems was used as the basis for understanding sustainability. The level of development attainable is related to the rate of degradation of available energy and inversely related to environmental uncertainty. This 'development by self-organization' is unsustainable, whether based on non-renewable or renewable resources. A second concept of development relates to solving the problem of achieving desirable social goals. This can be called 'development by design'. Development by design in the context of sustainability involves a contradiction between short-term and long-term goals which cannot in principle be solved. Real life resolutions generally favour the short-term goals. The heuristic of an adaptability / efficiency trade-off was found to be as useful for issues of 'development by design' as it is for 'development by self-organization.' Since neither type of development is expected to be sustainable, the importance of preserving the conditions for renewed development after crisis are highlighted.

Urban water demand management helps to meet social goals with respect to adequate water supply and protection of local natural aquatic environments. By easing a restraint on urban growth, demand management promotes economic development. This accelerates the trend towards unsustainability. However, water demand management helps to maintain environmental local conditions needed for post-crisis recovery. This general analysis was supplemented by the analysis of three specific urban water demand management problems: (I) In a case study based on recent planning initiatives in the Regional Municipality of Waterloo, Ontario, it was found that demand management had not been as well integrated with the planning for water supply and wastewater infrastructure as it might have been. (2) A simulation model was developed which forecasts water use, water prices and the timing of expansions in water supply capacity. The unique feature of the model is the incorporation of anticipatory price smoothing. The model was successful in illustrating the need for integrating price forecasting with demand forecasting and capacity expansion planning. (3) There is the possibility with a summer water use price structure that customers with high summer water use may deliberately waste water in the winter. An analysis of summer water use pricing was done which determined the relationship of the price ratio (summer use price to base use price) to other pricing parameters needed to avoid such wastage. An emphasis on water demand management, whether motivated by water availability limits, wastewater assimilation limits, or economic limits, is a symptom of the drive for efficiency. A need for more integrated planning is likely to be felt in systems which are approaching limits because of the increase in connectedness which occurs in such systems. Other issues raised were: the energy cost of water as an economic commodity, especially in times when the dollar cost of energy is increasing; the complexity of an urban water system in relation to its vulnerability to external (economic or natural) perturbation; longterm environmental carrying capacity; and the importance of avoiding measures which might reduce the variability, and hence the adaptability, of the city economy.