AbstractsGeography &GIS

Water resources around the world are under increasing pressure from growing populations and the matching demand for food. Climate change is making its presence felt through trends to decreased rainfall and increased temperatures and evaporation rates, resulting in longer and more frequent spells of dry weather. Urban areas are competing more strongly with irrigated agriculture, industry and the environment for a share of the water supply. Urban water demand management has thus come into sharper focus as an integral part of any sustainable water management strategy. Urban irrigation, the watering of lawns and garden beds in the residential sector and irrigation of public open spaces like sporting grounds and parks, forms a significant component of urban water demand. Irrigation demand provides, in theory, more scope and opportunities for demand reduction and water use efficiency than indoor water demand, but in practice indoor demand has received greater levels of attention and investment from urban water service providers. This is because urban irrigation demand and its water saving potential, influenced by a complex set of climatic, biophysical, technological and behavioural factors, are relatively more difficult to analyse and predict. A random approach to the development of outdoor demand management programs, the lack of evaluation of such programs where they exist, and reliance on mandatory water restrictions for achieving reductions in demand, are symptoms of the problem. The thesis seeks to address the problem by proposing a modelling framework based around the concepts of landscape irrigation budget and water saving potential, and argues that the proposed framework provides a rational and systematic approach to development of demand management policies and programs for urban irrigation through its capacity to: (a) develop irrigation benchmarks and budgets for different urban landscape types located in different soil–climate zones; and (b) evaluate the effectiveness of demand management programs and policies. The thesis explores this proposition by applying the proposed concepts and framework to a selection of domestic gardens attached to single detached dwellings located in the local government areas of Kogarah and Penrith, representing two different soil–climate zones within the Greater Sydney Metropolitan area of New South Wales, Australia. The research methodology integrates the following: (a) a survey of domestic gardens, using aerial photographs, to characterise them with respect to their area, water use and microclimate characteristics; (b) building a conceptual biophysical model using a rational approach to estimate landscape irrigation budget for those gardens; (c) estimating irrigation budgets for gardens in the two areas; (d) water demand modelling using historical metered water consumption data (for a period when there were no water restrictions) to estimate the water saving potential of those gardens; and (e) analysis of historical metered consumption data (for a period when water restrictions…