Are you watering your lawn? High-resolution data may help to devise effective water conservation strategies in urban areas around the world By Terri S. Hogue1 and Stephanie Pincetl2
PHOTOS: (LEFT) LUCY NICHOLSON/REUTERS/CORBIS; (RIGHT) ALBERTO RIGAMONTI/THINKSTOCK
I
ing restrictions. The City of Los Angeles, which imports over 90% of its water supply, is under mayoral directive to reduce imported water by 50% and increase local water sources. Policies to conserve water differ widely across urban centers and are formulated based on institutional structure, history, and governing bodies. Common practices include price increases or pricing structure change (altering or expanding a tier structure), volume reductions, policing efforts and fines, watering restrictions, and landscape replacement programs. There is evidence that nonpecuniary strategies such as social comparisons of water use can make some difference in water consumption as well, especially for high users, but the effects are not large (4).
Historical research on water use in cities has relied on intelligent intuition, modeled data, or small-sample data. Early work in California was driven by the Pacific Institute (6), which relied mainly on population estimates and empirical coefficients for statewide regions. More recent analyses have used multivariate or statistical regression models to evaluate urban demand (7, 8), although still largely based on modeled data. For example, Balling and Gober evaluated the response of annual water use to climate conditions in Phoenix, Arizona (7). Although overall water use fell over the study period, annual water use rose with higher temperatures, lower precipitation, and drought conditions. Watering habits suggest that many residents were unaware of optimal watering for their landscapes. Mini et al. found residential water use in Los Angeles to be driven by household income, landscape greenness, water rates, and allocated volumes (8), with 10% of single-family customers using 30% of all residential water in the city. Outdoor water use accounts for a large percentage of total water use in many arid cities, ranging from 40 to 70% depending on climate, pricing, and sociodemographic fac-
ncreases in urban populations, particularly in semi-arid cities, have led to unsustainable water use in many regions of the world. Water is frequently drawn from outside urban boundaries, but these remote water sources are becoming less reliable due to global climate change and regional political conflict. In response, urban water conservation efforts have been expanding and cities are pressured to reduce demand. Yet, as seen currently in California, measures to reduce water use are having limited effect (1). Can better data help to underpin water use policy? Between 2003 and 2012, Australia experienced the longest and most severe drought on record, prompting extensive conservation efforts to maintain water supplies (2). In Brazil, the states of São Paulo and Rio de Janeiro are at their lowest levels of water supply in 80 years, with reservoirs at ~5% of capacity. Water managers in these states are targeting conservation efforts at those with high consumption levels, offering discounts for reduced use and decreasing allotments to industry and agriculture (3). The ongoing drought in California drought. A field of dead almond trees in Coalinga in the Central Valley, California, on 6 May 2015 (left) illustrates the severity of the western United States the ongoing drought. In response, state water regulators have recently adopted mandatory cutbacks in urban water use (right). (see the photos) has also led to accelerated efforts in water conservation However, few studies have evaluated the tors (9). Work in this area is accelerating as and expanded regulation on groundwater effect of implemented conservation meamanagers look for methods to better refine consumption. sures, especially across diverse socioecooutdoor use and landscape irrigation. For The governor of California has declared nomic groups, citywide regions, or water example, Kaplan et al. (10) used high-resoemergency mandatory restrictions to districts. Institutions generally track citylution Landsat data and an evapotranspiraachieve a 25% statewide reduction in potawide water consumption trends, but rarely tion model to estimate outdoor water use ble urban water use. Cities across the state is there detailed spatial and temporal analyand drought response in the Phoenix area. are drafting integrated water management sis to quantify where and when conservation Evapotranspiration (the water transmitted plans that include viewing all water sources efforts are successful or where efforts should back to the atmosphere through plants) and (including, for example, recycled wastewabe reformulated to reach consumers who are water consumption values stayed elevated ter and storm runoff ) as suitable for coninsensitive to implemented policies. For exover agricultural regions during drought, sumption. The cities are also accelerating ample, outdoor water use is often reduced whereas urban landscape and the surroundwater conservation efforts, including new during a period of drought but may rebound ing desert regions showed lower evapotier pricing regimes and mandatory wateror even increase after there has been rain. transpiration and overall water use during Moreover, little is known about the relationdrought. Thus, conservation measures for ship between water use reductions and repark areas in Phoenix during drought years 1 Department of Civil and Environmental Engineering, Colorado gional urban greenness, although concern appear to have been effective. Mini et al. School of Mines, Golden, CO 80401, USA. 2Institute of the Enviabout this is often behind resistance to water have shown that in Los Angeles, where outronment and Sustainability, UCLA, Los Angeles, CA 90095, USA. conservation (5). door use accounts for 54% of residential E-mail: [email protected] SCIENCE sciencemag.org
19 JUNE 2015 • VOL 348 ISSUE 6241
Published by AAAS
1319
Downloaded from www.sciencemag.org on June 18, 2015
WATER CONSERVATION
INSIGHTS | P E R S P E C T I V E S
REFERENCES AND NOTES
1. See, for example, www.theguardian.com/us-news/2015/may/05/ california-falls-short-water-saving-target-drought. 2. B. Neal et al., Water Management 167, 435 (2014). 3. NPR, A historic drought grips Brazil’s economic capital (10 February 2015; www.npr.org/sections/ parallels/2015/02/10/384971276/a-historic-droughtgrips-brazils-economic-capital. 4. P. J. Ferraro, M. K. Price, Rev. Econ. Stat. 95, 64 (2013). 5. C. Carandang, thesis, Civil and Environmental Engineering, Colorado School of Mines, Golden, CO (2015). 6. P. H. Gleick et al., Waste Not Want Not: The Potential for Urban Water Conservation in California (Pacific Institute, Oakland, CA, 2003), appendix B. 7. R. C. Balling Jr., P. Gober, J. Appl. Meteorol. Climatol. 46, 1130 (2007). 8. C. Mini et al., Water Policy 16, 1054 (2014). 9. R. St. Hilaire et al., HortScience 43, 2081 (2008). 10. S. Kaplan et al., Environ. Manage. 53, 855 (2014). 11. C. Mini et al., Resour. Conserv. Recycling 94, 136 (2015). 12. C. D. Beal, J. Flynn, The 2014 Review of Smart Metering and Intelligent Water Networks in Australia and New Zealand (Report prepared for Water Services Association of Australia by the Smart Water Research Centre, Griffith University, Gold Coast, Queensland, Australia, November 2014). 13. T. R. Gurung et al., J. Clean. Prod. 87, 642 (2015). 14. T. Boyle et al., Water 5, 1052 (2013). 15. D. P. Giurco, S. B. White, R. A. Stewart, Water 2, 461 (2010). 10.1126/science.aaa6909
1320
Foreign ministers discuss Iran’s nuclear program in Lausanne, April 2015.
NUCLEAR SECURITY
After the Iran deal: Multinational enrichment World powers should buy a stake in Iran’s enrichment capacity and accept the same rules By Alexander Glaser, Zia Mian,* Frank von Hippel
I
n April 2015, Iran and the E3+3 nations (France, Germany, and the United Kingdom, plus China, Russia, and the United States) negotiated a framework for a “comprehensive solution that will ensure the exclusively peaceful nature of the Iranian nuclear program” (1, 2). The final settlement, expected by July 2015 or soon after, would constrain Iran’s activities for various extended periods in return for the lifting of sanctions and affirm Iran’s right to pursue its nuclear program POLICY free of the limits on its uranium enrichment capacity a decade or more from now. What happens when these restrictions begin to phase out? We outline one approach to limit the long-term risk by using the next 10 years to convert Iran’s national enrichment plant into a multinational one, possibly including as partners some of Iran’s neighbors and one or more of the E3+3 countries. After Iran’s enrichment efforts were made public in 2003, the United States organized a broad alliance to pressure Iran to end this program, fearing that it was seeking nuclear weapons. Despite ever more punishing international sanctions, Iran built up its enrichment capacity, insisting that this program was peaceful and permitted under the 1968 nonproliferation treaty (NPT), which recognizes an “inalienable right of all the Parties to the Treaty to develop research, production
and use of nuclear energy for peaceful purposes without discrimination” (3). As part of its efforts to address concerns about the proliferation risks from its nuclear program, in November 2013 Iran agreed with the E3+3 on a Joint Plan of Action involving temporary limitations on its nuclear activities in exchange for limited sanctions relief (4). The April 2015 framework for a final settlement builds on the joint plan and includes limiting Iran to one operating enrichment plant (at Natanz); placing limits on its capacity, enrichment level, and stockpile of enriched uranium for “specified durations”; and an agreed-upon plan for Iran’s centrifuge research and development. It also includes constraints on the plutonium production capacity of research reactors and an agreement by Iran not to separate plutonium from spent fuel or other irradiated uranium. The final element is increased transparency, including of centrifuge fabrication, and enhanced access for International Atomic Energy Agency (IAEA) inspectors to assure compliance. These transparency measures encompass and go beyond the reporting and access obligations of normal IAEA safeguards on NPT nonweapon states, including an additional protocol to the IAEA safeguards agreement, which Iran has signed and agreed to implement. Program on Science and Global Security, Princeton University, Princeton, NJ, USA. *Corresponding author. E-mail: [email protected]
sciencemag.org SCIENCE
19 JUNE 2015 • VOL 348 ISSUE 6241
Published by AAAS
PHOTO: GLEN JOHNSON/US STATE DEPARTMENT
water consumption, mandatory restrictions improved total water savings by up to 23%, whereas voluntary water restrictions resulted in only 6% water savings (11). Data from water meters can also help to inform water conservation measures. Progress is being made in dual metering (indoor/ outdoor billing segregation), smart metering (real-time monitoring that transmits to the utility), and intelligent metering (real-time monitoring that can also include informational feedback and control options) (12, 13). The extensive, detailed data provide valuable information on consumer use to utilities and resource managers. However, smart and intelligent metering systems are expensive and not yet widely used (14). The data are typically not in a user-friendly format, requiring sophisticated data processing for analysis. Further work is also needed to better understand how information from advanced metering technologies can help to influence consumer water use (15). If detailed observational data are combined with other databases and advanced models, they can inform targeted water conservation efforts. However, many water agencies do not have technical capacity to mine data over time and analyze change. For example, the current drought in California has led to calls to develop and report water use analysis, because agencies lack the ability to differentiate indoor and outdoor water use to evaluate the effectiveness of water conservation measures. Applying water use models that acknowledge sociodemographic characteristics and local characteristics, such as size of residence, outdoor water use, and vegetation, will be crucial for meeting water conservation goals and targets. ■
Are you watering your lawn? Terri S. Hogue and Stephanie Pincetl Science 348, 1319 (2015); DOI: 10.1126/science.aaa6909
This copy is for your personal, non-commercial use only.
If you wish to distribute this article to others, you can order high-quality copies for your colleagues, clients, or customers by clicking here.
The following resources related to this article are available online at www.sciencemag.org (this information is current as of June 18, 2015 ): Updated information and services, including high-resolution figures, can be found in the online version of this article at: http://www.sciencemag.org/content/348/6241/1319.full.html This article cites 10 articles, 1 of which can be accessed free: http://www.sciencemag.org/content/348/6241/1319.full.html#ref-list-1 This article appears in the following subject collections: Geochemistry, Geophysics http://www.sciencemag.org/cgi/collection/geochem_phys
Science (print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by the American Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005. Copyright 2015 by the American Association for the Advancement of Science; all rights reserved. The title Science is a registered trademark of AAAS.
Downloaded from www.sciencemag.org on June 18, 2015
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PHOTOS: (LEFT) LUCY NICHOLSON/REUTERS/CORBIS; (RIGHT) ALBERTO RIGAMONTI/THINKSTOCK
I
ing restrictions. The City of Los Angeles, which imports over 90% of its water supply, is under mayoral directive to reduce imported water by 50% and increase local water sources. Policies to conserve water differ widely across urban centers and are formulated based on institutional structure, history, and governing bodies. Common practices include price increases or pricing structure change (altering or expanding a tier structure), volume reductions, policing efforts and fines, watering restrictions, and landscape replacement programs. There is evidence that nonpecuniary strategies such as social comparisons of water use can make some difference in water consumption as well, especially for high users, but the effects are not large (4).
Historical research on water use in cities has relied on intelligent intuition, modeled data, or small-sample data. Early work in California was driven by the Pacific Institute (6), which relied mainly on population estimates and empirical coefficients for statewide regions. More recent analyses have used multivariate or statistical regression models to evaluate urban demand (7, 8), although still largely based on modeled data. For example, Balling and Gober evaluated the response of annual water use to climate conditions in Phoenix, Arizona (7). Although overall water use fell over the study period, annual water use rose with higher temperatures, lower precipitation, and drought conditions. Watering habits suggest that many residents were unaware of optimal watering for their landscapes. Mini et al. found residential water use in Los Angeles to be driven by household income, landscape greenness, water rates, and allocated volumes (8), with 10% of single-family customers using 30% of all residential water in the city. Outdoor water use accounts for a large percentage of total water use in many arid cities, ranging from 40 to 70% depending on climate, pricing, and sociodemographic fac-
ncreases in urban populations, particularly in semi-arid cities, have led to unsustainable water use in many regions of the world. Water is frequently drawn from outside urban boundaries, but these remote water sources are becoming less reliable due to global climate change and regional political conflict. In response, urban water conservation efforts have been expanding and cities are pressured to reduce demand. Yet, as seen currently in California, measures to reduce water use are having limited effect (1). Can better data help to underpin water use policy? Between 2003 and 2012, Australia experienced the longest and most severe drought on record, prompting extensive conservation efforts to maintain water supplies (2). In Brazil, the states of São Paulo and Rio de Janeiro are at their lowest levels of water supply in 80 years, with reservoirs at ~5% of capacity. Water managers in these states are targeting conservation efforts at those with high consumption levels, offering discounts for reduced use and decreasing allotments to industry and agriculture (3). The ongoing drought in California drought. A field of dead almond trees in Coalinga in the Central Valley, California, on 6 May 2015 (left) illustrates the severity of the western United States the ongoing drought. In response, state water regulators have recently adopted mandatory cutbacks in urban water use (right). (see the photos) has also led to accelerated efforts in water conservation However, few studies have evaluated the tors (9). Work in this area is accelerating as and expanded regulation on groundwater effect of implemented conservation meamanagers look for methods to better refine consumption. sures, especially across diverse socioecooutdoor use and landscape irrigation. For The governor of California has declared nomic groups, citywide regions, or water example, Kaplan et al. (10) used high-resoemergency mandatory restrictions to districts. Institutions generally track citylution Landsat data and an evapotranspiraachieve a 25% statewide reduction in potawide water consumption trends, but rarely tion model to estimate outdoor water use ble urban water use. Cities across the state is there detailed spatial and temporal analyand drought response in the Phoenix area. are drafting integrated water management sis to quantify where and when conservation Evapotranspiration (the water transmitted plans that include viewing all water sources efforts are successful or where efforts should back to the atmosphere through plants) and (including, for example, recycled wastewabe reformulated to reach consumers who are water consumption values stayed elevated ter and storm runoff ) as suitable for coninsensitive to implemented policies. For exover agricultural regions during drought, sumption. The cities are also accelerating ample, outdoor water use is often reduced whereas urban landscape and the surroundwater conservation efforts, including new during a period of drought but may rebound ing desert regions showed lower evapotier pricing regimes and mandatory wateror even increase after there has been rain. transpiration and overall water use during Moreover, little is known about the relationdrought. Thus, conservation measures for ship between water use reductions and repark areas in Phoenix during drought years 1 Department of Civil and Environmental Engineering, Colorado gional urban greenness, although concern appear to have been effective. Mini et al. School of Mines, Golden, CO 80401, USA. 2Institute of the Enviabout this is often behind resistance to water have shown that in Los Angeles, where outronment and Sustainability, UCLA, Los Angeles, CA 90095, USA. conservation (5). door use accounts for 54% of residential E-mail: [email protected] SCIENCE sciencemag.org
19 JUNE 2015 • VOL 348 ISSUE 6241
Published by AAAS
1319
Downloaded from www.sciencemag.org on June 18, 2015
WATER CONSERVATION
INSIGHTS | P E R S P E C T I V E S
REFERENCES AND NOTES
1. See, for example, www.theguardian.com/us-news/2015/may/05/ california-falls-short-water-saving-target-drought. 2. B. Neal et al., Water Management 167, 435 (2014). 3. NPR, A historic drought grips Brazil’s economic capital (10 February 2015; www.npr.org/sections/ parallels/2015/02/10/384971276/a-historic-droughtgrips-brazils-economic-capital. 4. P. J. Ferraro, M. K. Price, Rev. Econ. Stat. 95, 64 (2013). 5. C. Carandang, thesis, Civil and Environmental Engineering, Colorado School of Mines, Golden, CO (2015). 6. P. H. Gleick et al., Waste Not Want Not: The Potential for Urban Water Conservation in California (Pacific Institute, Oakland, CA, 2003), appendix B. 7. R. C. Balling Jr., P. Gober, J. Appl. Meteorol. Climatol. 46, 1130 (2007). 8. C. Mini et al., Water Policy 16, 1054 (2014). 9. R. St. Hilaire et al., HortScience 43, 2081 (2008). 10. S. Kaplan et al., Environ. Manage. 53, 855 (2014). 11. C. Mini et al., Resour. Conserv. Recycling 94, 136 (2015). 12. C. D. Beal, J. Flynn, The 2014 Review of Smart Metering and Intelligent Water Networks in Australia and New Zealand (Report prepared for Water Services Association of Australia by the Smart Water Research Centre, Griffith University, Gold Coast, Queensland, Australia, November 2014). 13. T. R. Gurung et al., J. Clean. Prod. 87, 642 (2015). 14. T. Boyle et al., Water 5, 1052 (2013). 15. D. P. Giurco, S. B. White, R. A. Stewart, Water 2, 461 (2010). 10.1126/science.aaa6909
1320
Foreign ministers discuss Iran’s nuclear program in Lausanne, April 2015.
NUCLEAR SECURITY
After the Iran deal: Multinational enrichment World powers should buy a stake in Iran’s enrichment capacity and accept the same rules By Alexander Glaser, Zia Mian,* Frank von Hippel
I
n April 2015, Iran and the E3+3 nations (France, Germany, and the United Kingdom, plus China, Russia, and the United States) negotiated a framework for a “comprehensive solution that will ensure the exclusively peaceful nature of the Iranian nuclear program” (1, 2). The final settlement, expected by July 2015 or soon after, would constrain Iran’s activities for various extended periods in return for the lifting of sanctions and affirm Iran’s right to pursue its nuclear program POLICY free of the limits on its uranium enrichment capacity a decade or more from now. What happens when these restrictions begin to phase out? We outline one approach to limit the long-term risk by using the next 10 years to convert Iran’s national enrichment plant into a multinational one, possibly including as partners some of Iran’s neighbors and one or more of the E3+3 countries. After Iran’s enrichment efforts were made public in 2003, the United States organized a broad alliance to pressure Iran to end this program, fearing that it was seeking nuclear weapons. Despite ever more punishing international sanctions, Iran built up its enrichment capacity, insisting that this program was peaceful and permitted under the 1968 nonproliferation treaty (NPT), which recognizes an “inalienable right of all the Parties to the Treaty to develop research, production
and use of nuclear energy for peaceful purposes without discrimination” (3). As part of its efforts to address concerns about the proliferation risks from its nuclear program, in November 2013 Iran agreed with the E3+3 on a Joint Plan of Action involving temporary limitations on its nuclear activities in exchange for limited sanctions relief (4). The April 2015 framework for a final settlement builds on the joint plan and includes limiting Iran to one operating enrichment plant (at Natanz); placing limits on its capacity, enrichment level, and stockpile of enriched uranium for “specified durations”; and an agreed-upon plan for Iran’s centrifuge research and development. It also includes constraints on the plutonium production capacity of research reactors and an agreement by Iran not to separate plutonium from spent fuel or other irradiated uranium. The final element is increased transparency, including of centrifuge fabrication, and enhanced access for International Atomic Energy Agency (IAEA) inspectors to assure compliance. These transparency measures encompass and go beyond the reporting and access obligations of normal IAEA safeguards on NPT nonweapon states, including an additional protocol to the IAEA safeguards agreement, which Iran has signed and agreed to implement. Program on Science and Global Security, Princeton University, Princeton, NJ, USA. *Corresponding author. E-mail: [email protected]
sciencemag.org SCIENCE
19 JUNE 2015 • VOL 348 ISSUE 6241
Published by AAAS
PHOTO: GLEN JOHNSON/US STATE DEPARTMENT
water consumption, mandatory restrictions improved total water savings by up to 23%, whereas voluntary water restrictions resulted in only 6% water savings (11). Data from water meters can also help to inform water conservation measures. Progress is being made in dual metering (indoor/ outdoor billing segregation), smart metering (real-time monitoring that transmits to the utility), and intelligent metering (real-time monitoring that can also include informational feedback and control options) (12, 13). The extensive, detailed data provide valuable information on consumer use to utilities and resource managers. However, smart and intelligent metering systems are expensive and not yet widely used (14). The data are typically not in a user-friendly format, requiring sophisticated data processing for analysis. Further work is also needed to better understand how information from advanced metering technologies can help to influence consumer water use (15). If detailed observational data are combined with other databases and advanced models, they can inform targeted water conservation efforts. However, many water agencies do not have technical capacity to mine data over time and analyze change. For example, the current drought in California has led to calls to develop and report water use analysis, because agencies lack the ability to differentiate indoor and outdoor water use to evaluate the effectiveness of water conservation measures. Applying water use models that acknowledge sociodemographic characteristics and local characteristics, such as size of residence, outdoor water use, and vegetation, will be crucial for meeting water conservation goals and targets. ■
Are you watering your lawn? Terri S. Hogue and Stephanie Pincetl Science 348, 1319 (2015); DOI: 10.1126/science.aaa6909
This copy is for your personal, non-commercial use only.
If you wish to distribute this article to others, you can order high-quality copies for your colleagues, clients, or customers by clicking here.
The following resources related to this article are available online at www.sciencemag.org (this information is current as of June 18, 2015 ): Updated information and services, including high-resolution figures, can be found in the online version of this article at: http://www.sciencemag.org/content/348/6241/1319.full.html This article cites 10 articles, 1 of which can be accessed free: http://www.sciencemag.org/content/348/6241/1319.full.html#ref-list-1 This article appears in the following subject collections: Geochemistry, Geophysics http://www.sciencemag.org/cgi/collection/geochem_phys
Science (print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by the American Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005. Copyright 2015 by the American Association for the Advancement of Science; all rights reserved. The title Science is a registered trademark of AAAS.
Downloaded from www.sciencemag.org on June 18, 2015
Permission to republish or repurpose articles or portions of articles can be obtained by following the guidelines here.
