Individualized and Combined Effects of Future Urban Growth and Climate Change on Irrigation Water Use in Central Arizona

• Published in: Journal of the American Water Resources Association Vol. 58; no. 3; pp. 370 - 387
• Main Authors: Wang, Zhaocheng, Vivoni, Enrique R.
• Format: Journal Article
• Language: English
• Published: Middleburg Blackwell Publishing Ltd 01.06.2022
• Subjects: Agricultural land; arid lands; Arid regions; Arid zones; Climate change; climate variability/change; computational methods; Irrigation; Irrigation practices; Irrigation water; land surface model; Land use; land use/land cover change; Metropolitan areas; Residential areas; sustainability; Urban agriculture; Urban areas; Urban development; Urban environments; Urban sprawl; Urbanization; Water conservation; Water consumption; Water management; Water use
• ISSN: 1093-474X; 1752-1688
• DOI: 10.1111/1752-1688.13005

Irrigation in agricultural and urban settings is responsible for nearly 80% of the water use in the Phoenix Metropolitan Area. Over the last three decades, there has been a continuous decrease in cropland area and its water consumption. Meanwhile, urbanization has increased outdoor irrigation to maintain residential areas and parks. Given these trends, irrigation water use (IWU) is subject to large uncertainties which challenge land and water management. In this work, we used a land surface model with an irrigation module to quantify urban and agricultural IWU under the individualized and combined effects of future urban growth and anticipated climate change. A large set of scenario combinations (96 in total) allowed us to bracket plausible pathways of IWU change in the 21st Century. We found that land use change reduced IWU by −4.6% to −0.1% due to savings from crop‐urban conversion, while climate change effects led to increases in IWU by +3.8% to +8.6%. When combined, total IWU changed from +2.5% to +5.8% in the intermediate future (2041–2070) and from −0.5% to 6.8% in the far future (2071–2100). These outcomes suggest that water savings from land use change will likely not be able to compensate for the increasing demand from urban irrigation when considering climate change, under current irrigation practices. Our approach to model the interconnections between land and water under climate change can be used to support sustainable water planning in cities in other arid regions. Research Impact Statement: Central Arizona will likely have higher irrigation water use under the combined effects of climate and land use changes.