Taking account of water supply infrastructure in landuse planning: An integrated supply-demand approach

Demographic pressures have led the UK Government to embark upon a substantial programme of new housing development across the country, with particular emphasis on the south and south east of England where demand is greatest. The new developments will require careful planning in terms of their geographical location, timing and in terms of infrastructure, as the current water supply network in the south and south east of England is unlikely to be able to deliver adequate, reliable supplies to planned new developments without significant investment. How should the infrastructure be expanded to best meet changes in water demand from new housing? How should new housing be planned to minimise stress on existing infrastructure and reduce total investment costs? This paper presents a novel simulation tool, INFRAPLAN, developed to provide a means of exploring different demographic, land-use planning, water demand and infrastructure investment scenarios for a 49km x 59km region in south east England. INFRAPLAN integrates a cell-based land-use change model with a network-based hydraulic simulator and provides output which can be run through the built-in optimisation engine to determine the best (least cost, maximum performance) infrastructure expansion plan. The structure and operation of INFRAPLAN is described along with results from scenarios representing variations in demographic pressure, land-use plans and infrastructure expansion. The role of integrated assessment models such as INFRAPLAN are then discussed