Tapped Out: Growing Cities in Search of the Next Oasis

Richter, B.D., D Abell, E Bacha, K Brauman, S Calos, A Cohn, C Disla, S Friedlander O’Brien, D Hodges, S Kaiser, M Loughran, C Mestre, M Reardon, and E Siegfried. 2013. Tapped out: growing cities in search of the next oasis. Water Policy 15 (2013) 335–363

ABSTRACT: Cities around the world are struggling to access additional water supplies to support their continued growth because their freshwater sources are becoming exhausted. Half of all cities with populations greater than

100,000 are located in water-scarce basins, and in these basins agricultural water consumption accounts for

more than 90% of all freshwater depletions. In this paper we review the water development histories of four

major cities: Adelaide, Phoenix, San Antonio and San Diego. We identify a similar pattern of water development

in these cities, which begins with the exhaustion of local surface and groundwater supplies, continues with importation of water from other basins, and then turns to recycling of wastewater or stormwater, or desalination of either seawater or brackish groundwater. Demand management through water conservation has mitigated, to varying degrees, the timing of water-system expansions and the extent to which cities rely on new sources of supply. This typical water development pattern in cities is undesirable from a sustainability perspective, as it is usually associated with serious ecological and social impacts as well as sub-optimal cost effectiveness. We highlight

case examples and opportunities to invest in water conservation measures, particularly through urban–rural partnerships under which cities work with farmers to implement irrigation conservation measures, thereby freeing up water for ecological restoration and use by cities.