Final Report: A Decision Support Tool for Sustainable Urban Water ManagementEPA Grant Number: SU831827
Title: A Decision Support Tool for Sustainable Urban Water Management
Investigators: Crittenden, John C. , Larson, Elisabeth , Corley, Elizabeth , Lyons, Erin , Johnson, Genevieve , Li, Hebi , Pokorski, Jennifer , Carlson, Joby , Li, Ke , Grimm, Nancy , McCartney, Peter , Guhathakurta, Subhrajit , Chen, Yongsheng
Institution: Arizona State University - Main Campus
EPA Project Officer: Page, Angela
Project Period: September 15, 2004 through September 14, 2005
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2004) RFA Text | Recipients Lists
Research Category: P3 Challenge Area - Water , Pollution Prevention/Sustainable Development , P3 Awards , Sustainability
The enormous growth of the human population in the twentieth century has led to a surge of population influx to urban centers. Currently ~45% of the world’s population lives in urban areas, a figure which is expected to grow by ~2.5% per year (UNEP, 2002). Cities around the world face the challenges of development and the stress of meeting the needs of the growing human population while managing and minimizing their impact on the natural environment. As the human population continues to increase, it will be essential to balance consumption and the production abilities of the planet so that humans will be able to meet their basic needs.
The existence of urbanized Phoenix is a graphic testament to the power of human planning and management to deal with severe climatic challenges. Located in an arid climate, the Phoenix area receives an average of 7 inches of rain annually. The average annual evapotranspiration is approximately 79 inches. Local water supplies are available in the form of the Salt and Verde Rivers and groundwater. Faced with a place that alternates between extreme aridity and episodic flooding, successive waves of desert dwellers took steps to implement one of the most extensive water storage and delivery systems on the planet. For example, in 1985 the Central Arizona Project (CAP) canal was built to carry water from the Colorado River to Phoenix . This physical infrastructure of dams, reservoirs, canals, and aqueducts, as well as the operating rules that govern its management, has insulated Phoenix from the harshness and uncertainty of its climate—until recently. The confluence of population growth and global warming threatens an already uncertain climatic environment. Phoenix is at the epicenter of areas in “potential water supply crisis by 2025,” a fact acknowledged by Interior Secretary Gale Norton’s Water 2025 Initiative. Phoenix added more than 100,000 residents annually between 2000 and 2002 (from 3.25 to 3.49 million) and is projected to grow to 4.5 million in 2020 and to 6.3 million by 2040 (Arizona Department of Economic Security 2002) with predictable increases in urban water demand. Added to demographic pressure is uncertainty associated with global climate change that has the potential to produce a substantive increase in the duration, frequency, and severity of droughts in the region (Houghton et al. 2001). The Growing concerns among water managers have brought them to collaborate with ASU engineers, scientists and policy analysts to enhance the region’s water sustainability.
The goal of water sustainability is to ensure adequate and safe water for drinking, personal hygiene, recreation, and irrigation while protecting the water resources and environment for future generations. The following questions are important in urban water management: How much water is needed? Where does the water come from? Is the water safe for human health? How can we avoid or minimize the environmental impact associated with urban water use? The traditional approach addresses these problems separately and it is difficult to get a complete view of the sustainability of urban water management. To enhance the sustainability of urban water management in Phoenix, our P3 project developed a systems approach that integrated different aspects of urban water management in relation to each other. A sustainable society is one that is informed and can make educated choices on sustainable options and decisions. To achieve sustainable urban water management, it is also necessary to educate the decision makers, including policy makers, water providers, and water consumers on sustainable alternatives and consequences. The culmination of our P3 project was the development of visualization tools for education and knowledge transfer.
Many other urban areas are located in arid and semi-arid climates and face the same challenges as Phoenix. For those urban areas which now have plentiful water resources, they will eventually face these challenges as the population keeps growing. In many urban areas, as in Phoenix, the growing demand has largely been met by improving and expanding storage and distribution systems as well as by mining of groundwater resources. This approach is now realized to be unsustainable because of the associated environmental impact. For example, groundwater overdraft in Phoenix has resulted in declining of groundwater levels, subsidence and earth fissuring, aquifer compaction, and water quality problems due to the migration of poor quality water along with the general deterioration of aquifer water quality with depth (Arizona Department of Water Resources, 1999). Phoenix’s past success, the severity of its current risk and the magnitude of future demand reflect the reality of many urban areas. For this reason, Phoenix is a superb laboratory for studying sustainable water management which can contribute approaches and results helpful to other urban areas facing water sustainability issues.
Urban water management involves interactions between human social decision-making, water resources, water infrastructure, and the environment. To meet the water needs of evergrowing populations while balancing the concerns about the environment, it is increasingly necessary for policy makers to look at urban water management from a big picture view and to understand how their decisions have influence on urban water demand, water infrastructure and the environment. A decision support tool that captures the dynamic relationships between urban development, water demand and environmental impact is necessary to aid in social decision making. Therefore the goal of this project was to develop a decision support tool for urban water management.
Summary of Findings: The full scope of this project includes the following: (1) integrate social decision making, urban development and land use, water demand and infrastructure, and environmental issues in urban water management; (2) determine the impact of urban development and social decisions on water demand and infrastructure; (3) determine the impact of urban water use on the environment; (4) develop educational products for education and knowledge transfer; (5) work with local agencies to examine the utility of our approach for their situations. The specific objectives of this project include: (1) perform urban development modeling; (2) perform water demand modeling; (3) analyze environmental impact exerted by urban water use; (4) Integrate sub-models into a decision support tool; (5) make presentations to local communities.
After much deliberation and study, it has been determined that the topic is an area of great interest with a strong potential for achievement, although the problem is very complicated. The successes of this phase were: a comprehensive understanding of the problem of urban growth and water demand and the complicating factors involved, development of a simplified model to simulate the interactions between urban development, water demand and environmental impact, and development of visualization tools for education and knowledge transfer. The developed tools can be used to assess the impacts of alternative urban development plans and policies on the urban water demand, infrastructure needed and the associated environmental impact, and therefore can be used to aid decision making in urban water management.
Proposed Phase II objectives and strategies:
Based on the investigation and study in Phase I, we came to realize that social decision making plays a critical role in urban water management. Social decision making determines the urban development patterns that have a large impact on the water consumption. Social decision making also determines water consumption behavior that has a large impact on the water consumption, too. In Phase I, we studied the impact of social decision making associated with urban development on the water demand. Because of the short time frame of Phase I, we did not put much effort to study the impact of social decision making associated with consumption behavior on the water demand, although we realize its importance in urban water management.
We have also realized that in the current practices urban planning and urban water planning are conducted separately. Urban water planning in many urban areas is usually based on completed urban projections. Those urban projections are sometimes produced by votes and missing a scientific basis. In some cases, the urban projections may be produced based on urban simulation modeling and have increased accuracy in representing future urban development patterns. However, the urban water planning which is separated from urban planning only tells the consequences of urban development and can not do anything to the urban planning process. Ill-planned urban development has caused many problems in urban water management. If we could foresee those problems in the process of urban planning, we could avoid inappropriate urban development patterns and minimize the occurrence of those problems. In addition, in the calculation of water demand, the water consumption behavior is usually assumed invariable. The uncertainties in urban projections and negligence of possible changes of water consumption behavior bring uncertainties to the water demand projection, and these uncertainties have a large impact on the water infrastructure.
The goal of Phase II is to further develop the decision support tool for urban water management developed in Phase I by including the following items that are missing in Phase I: (1) the impact of social decision making associated with water consumption behavior; (2) water quality and hydraulic modeling of water distribution network.