The Hydro-Economic Interdependency of Cities: Virtual Water Connections of the Phoenix, Arizona Metropolitan Area

Abstract

Abstract:Water footprinting has revealed hydro-economic interdependencies between distant global geographies via trade, especially of agricultural and manufactured goods. However, for metropolitan areas, trade not only entails commodity flows at many scales from intra-municipal to global, but also substantial intra-metropolitan flows of the skilled labor that is essential to a city's high-value economy. Virtual water flows between municipalities are directly relevant for municipal water supply policy and infrastructure investment because they quantify the hydro-economic dependency between neighboring municipalities. These municipalities share a physical water supply and also place demands on their neighbors' water supplies by outsourcing labor and commodity production outside the municipal and water supply system boundary to the metropolitan area. Metropolitan area communities span dense urban cores to fringe agricultural towns, spanning a wide range of the US hydro-economy. This study quantifies water footprints and virtual water flows of the complete economy of the Phoenix Metropolitan Area's municipalities. A novel approach utilized journey to work data to estimate virtual water flows embedded in labor. Commodities dominate virtual water flows at all scales of analysis, however labor is shown to be important for intra-metropolitan virtual water flows. This is the first detailed water footprint analysis of Phoenix, an important city in a water-scarce region. This study establishes a hydro-economic typology for communities to define several niche roles and decision making points of view. This study's findings can be used to classify communities with respect to their relative roles, and to benchmark future improvements in water OPEN ACCESS Sustainability 2015, 7 8523 sustainability for all types of communities. More importantly, these findings motivate cooperative approaches to intra-metropolitan water supply policy that recognize the hydro-economic interdependence of these municipalities and their shared interest in ensuring a sustainable and resilient hydro-economy for all members of the metropolitan area.

The vulnerability and resilience of a city's water footprint: The case of Flagstaff, Arizona, USA

“…Virtual water inflows ( V In ) and outflows ( V Out ) were calculated using commodity flows [ Rushforth and Ruddell , ] and disaggregated to the county level using regional shares (RS) of employment [ U.S. Census Buearu , ], agricultural establishments [ USDA NASS , ], and population [ U.S. Census Buearu , ]. Flagstaff's virtual water flows are a geographic extract from the National Water Economy Database (NWED).…”

“…A city balances direct physical water resource development against outsourcing of production of the goods and services of water. From this point of view, the city drives the flow of virtual water by outsourcing less valuable and more water‐intensive water uses [ Rushforth and Ruddell , ], and is the ultimate cause of the use of most water resources in the economy. Now the city takes its place in a continuum of hydro‐economic actors, ranging from small towns and rural natural resource operations up to megacities.…”

A Spatially Detailed and Economically Complete Blue Water Footprint of the United States

“…Secondly, the U.S. is a 386 large, and geographically, agronomically, climatically, and economically diverse country; water 387 use efficiencies vary dramatically from region-to-region and sector-to-sector. With respect to (4), this specifically includes flows of services and labor across county or 430 regional lines (Rushforth and Ruddell, 2015). There is a substantial absolute error introduced by 431 zeroing virtual water flows out from counties that export services and FAF-ignored goods, and 432 this error causes urban areas' net water footprints to be overestimated (and rural areas' to be 433 underestimated by exactly the same amount).…”

“…Page 24 of 54 city's economy (Rushforth and Ruddell, 2015). The Phoenix metropolitan area is notable as a 516 major city and population center that is simultaneously a large user of irrigation water for the 517 production of agricultural commodities, including locally consumed food products.…”

Review of the Water Footprint Project within Geographically Delineated Area

“…Richard Rushforth and Benjamin Ruddell [58] were the first to comprehensively analyze water footprints and virtual water flows within a municipality in metropolitan area, intra-metropolitan area flows, and national scale flows simultaneously. They quantified water footprints and virtual water flows of the complete economy of the Phoenix metropolitan area's municipalities.…”