Residential outdoor water use in Tucson, Arizona: Geospatial, demographic and temporal perspectives

Outdoor water use by single-family residences in the desert city of Tucson, Arizona is investigated as a multi-scaled coupled human-environment system, using remotely sensed images, GIS data, household water use records and survey responses. Like many desert cities, Tucson's municipal water system faces stresses at multiple spatial and temporal scales: rising demand, limited supplies, competition for distant resources and the likelihood of shortages due to regional climate change. Though the need for demand management is recognized, conflict between the long-term regional scale of the ecosystem that sustains Tucson's water supply and the short-term, local scale of the municipal utility results in a "lack of fit", shown here as the inability to reduce consumption to sustainable levels.;While direct regulation of outdoor water use has not been successful, geographic research suggests that modification of the built environment, the focus of the three studies comprising this dissertation, holds promise as a demand management strategy. The first study is a spatial analysis of survey responses on outdoor water use practices during a drought. Next, the potential for substituting common amenities (irrigated landscapes and swimming pools) for private ones is investigated. Residential use was found to be sensitive to park proximity, greenness (proxied by the Normalized Difference Vegetation Index), size and presence of a park pool. Most small parks were net water savers; large parks offered the opportunity to substitute reclaimed water for potable supplies.;The last study correlates long-term Landsat-based vegetation and water use trends and integrates these with a spatial analysis of kinetic temperatures. Findings indicate that despite reduced water use, Tucson became greener over the 1995 -- 2008 period. This effect is attributed to a pulse of vegetation establishment in response to a shift in the El Nino -- Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) around 1976 and to irrigation prior to the study period. I conclude that although the coupled human-environment system of Tucson's municipal water supply and use practices is complex, there are scale-dependent competitive advantages to be gained through thoughtful modification of the built environment.