Water Management, Conservation, and Preservation

Transcription

1 em feature by Suzanne Thomas-Cole, James Weinbauer, and Don Galya Suzanne Thomas-Cole, P.E., is program director, environment; James Weinbauer is vice president, sustainable development; and Don Galya, P.E., is vice president, water and natural resources all with AECOM. suzanne.t. Water Management, Conservation, and Preservation Sustainable water resource management is the next major global target that will lead corporations, governments, and others to develop system-wide solutions for water, public health, carbon, and energy use. A standardized and certifiable water footprint methodology is necessary to measure, assess, and reduce water usage impacts on humans and the environment. This discussion addresses the issues, risks, and methodologies leading the development of sustainable water management programs. Is Water the Next Carbon? Sustainable water is a term used by many different stakeholders in many different ways. The term links water resources with the sustainable management of water supply, usage, and discharge. As we work to conserve and preserve our water resources, concerns vary in degree of importance. For industry, especially those with high consumption levels, availability, reliability, and quality are the primary concerns. For municipalities, availability, reliability, and protection of quality are the key issues. For both public and private entities, the definition of risk tolerance will define how to manage water in a sustainable manner. For the public, conservation is paramount. As with carbon, water has become a global issue. The availability and quality of water has been a concern for many years. Water management practices are often hindered by ownership issues and water rights that are not clearly defined. Various government agencies manage quality through regulatory processes; however, no single agency is mandated to control the supply, address the cumulative impacts at the watershed level, and manage water availability. One agency may approve or permit consumption while others may permit discharge or govern quality. Water scarcity driven by frequent droughts in many parts of the world is intensified by over allocation and unchecked consumption. There is a need for an international water stewardship standard that is performancebased and aimed at sustainable water use. Multiple drivers justify water 8 em may 2011 awma.org

2 stewardship standards, including investor-driven disclosure and business risk identification, independent sustainability indices like the Dow Jones Sustainability Index, and customer-driven initiatives aimed at responsible management of water especially in arid climates. Adding to the complexity of sustainable water are the unknowns or externalities associated with climate change. Our response to the next carbon requires the use of integrated water management strategies in order to evaluate risks, mitigate controllable causes, and adapt to the extent feasible. For many, the drivers for action include business risk, sustainability, reduced costs, regulatory changes, increased compliance margin, and delivery reliability. The benefits of developing integrated water management strategies are great, and address the nature of sustainability by addressing the triple bottom line of environmental, social, and economic responsibility. Sustainable Water Management Emerging tools include the development of water footprints by corporate entities delineated by usage and business sector in addition to watershed footprints addressing supply, public health, use, and discharge. Figure 1 illustrates the progression of steps from simple process water footprints to more sophisticated product, consumer, or geographic footprints. Tools are rapidly developing to address each of these steps (Editor s Note: see Water Conservation Comes of Age Computing Your Water Footprint on page 13). Efforts are also aimed at the creation of a voluntary international water stewardship standard. The Alliance for Water Stewardship (allianceforwaterstewardship.org) is leading efforts through a multistakeholder process to develop an International Water Stewardship Standard that is intended to have broad applicability across sectors, habitats, and geographies. As an entity (facility or corporation) develops a sustainable water management program, the identification and quantification of water metrics is a critical first step. A few commonly used sources of water metrics and supporting tools include: Global Environmental Management Initiative (eoearth.org). This water reporting module includes three water profile forms: water use, impact, and source reliability. Global Reporting Initiative (GRI; globalreporting.org). The GRI is a generally accepted framework for reporting on an organization s economic, environmental, and social performance. The disclosures include a number of key water performance indicators, including total water withdrawal by source, sources significantly affected by withdrawal, percent and total volume recycled and reused, and total water discharged by quality and destination. awma.org may 2011 em 9

3 Figure 1. Water footprinting progression. Source: Water Footprint Network, University of Twente, The Netherlands Figure 2. Example risk factors for water users. Global Water Tool developed by the World Business Council for Sustainable Development (wbcsd.org). This tool allows companies to map water use and assess risks to global operations and supply chain. This tool uses an online spreadsheet calculator, including a water inventory with elements addressing water use, discharge, recycling, and consumption. This tool also compares water use to water availability along with other stress information available globally and presents a risk analysis for facilities or entire companies. Water Footprint Network (WFN; waterfootprint.org) and Water Footprint Working Group. The WFN s goals are to develop and apply water footprint methodologies in water management practices. Calculations are made by defining water volumes using the following three components: Green (rainwater evaporated during the production process; e.g., agricultural products, including crops and trees), Blue (volume of surface and groundwater evaporated as a result of production or service), and Grey (wastewater associated with production of goods and services; quantified as the volume required to dilute pollutants to meet water quality standards). National Council for Air and Stream Improvement (NCASI; ncasi.org). This water inventory tool tracks water use for the Forest Products Sector by including surface and groundwater inputs in fiber and non-fiber raw materials, use in processes, and water fate, including discharge to surface and groundwater, evaporation, water in residuals, and products. It considers the contribution of forests to freshwater supply. These metrics and tools are evolving from the public and private sector. No single water metric is currently capable of addressing all needs, including measuring impacts of local water use on humans residing in the region or local ecological conditions. 10 em may 2011 awma.org

4 Risk Factors Key factors in sustainable water management also include vulnerability and adaptation. Vulnerability to the effects of unsustainable water management is a function of both risk tolerance and the adaptive capacity of an organization. Figure 2 illustrates a simple prioritization of individual facility water footprints with identification of risk for these water users from drought conditions and longer term water scarcity/availability issues. Two primary risks are the potential for restrictions or loss of a water supply source, and increased flooding potential. Both of these risks have historically been experienced on a periodic basis globally. The U.S. Drought Monitor ( dm/monitor.html) illustrated in Figure 3 shows that even during the generally wet, snowy winter of 2010/2011 there was widespread drought in the southern United States. Climate change predictions for some locations, such as Southwest United States and Southern Europe, indicate these areas expect to experience decreased average precipitation with correspondingly decreased availability of water resources. Predictions also indicate that many locations will experience an increased potential for extreme high intensity precipitation events and resulting flooding. Some locations, such as the Northeast United States, are expected to have both more extreme precipitation events coupled with an increase in the number of dry days between precipitation events. As a result, there is an increased potential for both flooding and drought even at the same location. Other environmental risks to facilities that should be considered include water quality parameters that may restrict water use or require additional water treatment, low flow rates in receiving water bodies that lead to restrictive discharge permit limits, water quality and aquatic biology effects of wastewater discharges, and decreases in natural water resource availability and associated effects on aquatic biology and water quality due to consumptive water use. Adaptation Strategies The evaluation of potential adaptation strategies is crucial to a successful water management program. Strategies that consider engineering feasibility; costs and benefits; technological, logistical, political, regulatory, and institutional constraints; and uncertainties are needed. Some strategies that might be considered are discussed on the following page. awma.org may 2011 em 11

5 Figure 3. The U.S. Drought Monitor. Source: dm/monitor.html. Though it is not possible to ensure an available water supply that will meet all needs under all circumstances, the risk of an inadequate water supply can be reduced by developing supplemental water supply sources and decreasing/optimizing water demand. Potential water sources, in addition to surface water bodies and groundwater, include use of stormwater storage, flood skimming, grey water, or wastewater. Some of these would likely require treatment before use. Methods to decrease water demand include water use minimization/optimization, recycling, and xeriscaping (i.e., landscaping in ways that reduce or eliminate the need for supplemental water from irrigation) to reduce landscape watering needs. Decreasing water demands will reduce environmental risks to water resources, ecosystems, and aquatic biology. The potential for flooding is unavoidable. However, it is possible to manage the risk by flood proofing facilities (e.g., increasing the elevation of structures, using waterproof doors), using low-impact design methods to manage stormwater (e.g., retention and infiltration systems, reduction in impermeable surface area, constructed wetlands, green roofs), and protecting large-scale areas from flooding using flood control structures (e.g., levees) and increasing flood storage in a watershed using constructed wetlands and floodway buffer zones. Water quality risks can be minimized by evaluating the existing water quality standards for the source/ receiving waters, performing water quality modeling, assessing the need for site specific water quality criteria, and upgrading wastewater treatment systems to meet protective discharge permit limits. Minimization of waste streams will assist in reducing pollutant loads and associated water quality risks. Conclusion The integration of a whole system sustainability solution will include the management of water, carbon, and energy. As part of such a solution, individual facility, corporate, or geographical water management programs will address a range of factors and provide definition of and a pathway to reduce risk and achieve sustainable water management goals. Water stewardship standards that seek to identify and evaluate opportunities and risks in a multi-stakeholder environment will be the most successful. em 12 em may 2011 awma.org