Tuesday, 13 January 2009: 11:30 AM
The evolution of urban heat island and water demand
Room 124B (Phoenix Convention Center)
Urban water demand in the arid Southwestern U.S. is influenced by the type, age, and structure of residential and public landscaping. Urban heat island (UHI) coupled with regional climate change have important impacts on urban water demand. This paper relates 2000 – 2006 residential water use in Tucson, Arizona to modified Penman potential evapotranspiration (ETref) derived from weather station data. ETref exhibits increasing trends for the months of December – May, but declining trends for June – November. Tmin station data indicate that the rate of urban warming still remains greater than the regional warming trend, but that the rate of UHI urban-nonurban Tmin divergence has decreased, which is partially attributed to ET from irrigated urban vegetation. Geospatial analysis of normalized difference vegetation index (NDVI) and surface temperature derived from 1984 – 2005 Landsat Thematic Mapper imagery demonstrate the evolution of urban spatial patterns with stable NDVI of mature vegetation in the older urban core contrasted by increasing NDVI in the expanding urban fringes. Spatially disaggregated urban water use is shown to have similar patterns and follow similar temporal trends. The UHI implications of urban landscaping are discussed.