Water resource availability as a sustainability issue

Climate change is expected to affect global freshwater resources as precipitation patterns change, glaciers melt and sea levels rise. These effects will further intensify water stress experienced from population growth, economic development and industrial pollution. Water may thus be the limiting resource for many economic activities. Although the industrial sector takes up only about one-fifth of the water being used globally, water usage intensity is significant to all businesses whose sustainability will depend on its availability, cost and quality. Furthermore, with industries utilizing raw materials derived from agriculture, the sector which utilizes more than two-thirds of the global water consumption, water use in the industry may prove to be greater than what is immediately obvious. The link between industrial and agricultural activity indicates that the total water intensity (referred to as water footprint) of an organization is not only limited to the operational water directly utilized in processing the final product, but also includes the water utilized in all processes involved in the product supply chain. Water footprinting accounts for both direct and indirect water use in industrial systems making it a useful concept in dealing with transboundary concerns of virtual water trade vis-à-vis local water availability. This simply means that dry countries may opt to import water intensive products or services from nations with more water resources rather than manufacturing these items using their own limited supplies. The interested reader can visit the website http://www.waterfootprint.org for more information.

The concepts of virtual water (introduced by Allan in 1998) and water footprint have been used to assess the actual water intensity of products and processes. These were initially utilized to analyze the water footprint and virtual water trade of nations due to the consumption of agriculture-based products and have been recently extended to the product brand level. The concept of water footprint is utilized to assess water intensity at various levels of economic activity depending on the scope and goal of the study being undertaken. The main building blocks are the processes being accounted for either throughout a supply chain or as bounded by the region of interest. The total water footprint is defined as the associated amount of freshwater used to produce the goods and services consumed by a defined group, such as a business entity or a country. At the corporate level, the business water footprint will consist of the total amount of freshwater used (directly and indirectly) to run the business unit; it consists of operational water directly used by industrial plants, and the indirect water embedded in the raw materials utilized by the plant in the form of virtual water. The business water footprint is the total amount of water utilized in the supply chain of a business unit in order to support its activities and can be considered as a consumption-based indicator for water use. On the other hand, the water footprint may also be defined to account for the water intensity associated with all the activities within a specified geographical region, including the production of goods for export, local consumption and exhausting local resources. This second case reflects a production-based indicator of water use.

The total water footprint consists of three components, namely green water, blue water and gray water. Green water pertains to the amount of rainwater evaporated or rainwater incorporated in the product during the production process and is typically applicable to agricultural products. It accounts for the rainwater required to grow a given quantity of crop. Blue water is the amount of surface and ground water evaporated or incorporated into the product due to the production process and hence does not return to the environment in liquid form. If water is taken up in a process and returned to the environment in liquid form, the net consumption is zero, and all that is required is a footprint index that takes into account the degradation of water quality. According to Hoekstra and Chapagain (2007), this gray water footprint component refers to “the volume of water required to dilute pollutants to such an extent that concentrations are reduced to agreed maximum acceptable levels.” The overall water footprint is simply the sum of these components. In the production of cotton textile, for example, growing the crop requires water. This water requirement will consist of green and blue water footprints. Suppose, for example, that 2,000 tons of rainwater (green water) and 5,000 tons of irrigation water (blue water) are required to grow a ton of cotton. Furthermore, in order to process the cotton crop into textile, 1,000 tons of water are taken up from the environment, and returned as wastewater that meets legislated effluent standards, hence, the associated gray water is 1,000 tons. The total water footprint for the production of one ton of cotton textile is thus 8,000 (2,000 + 5,000 + 1,000) tons, a figure which is eight times more than the operational water used in the manufacturing stage.

My own recent research has dealt with the development of strategies for water conservation utilizing the concepts of water footprint and virtual water which was part of my Ph.D. work on an integrated approach to efficient water use in industrial ecosystems. The water footprint concept paints a better picture of the impact of products and services on water resources. The methodology I developed makes it possible to identify the optimized product supply chain of material and product exchange between different regions to satisfy the regional demand for products and achieve consumption- or production-based water footprint goals. This particular research was recently published in the Journal of Cleaner Production and is co-authored by Professors Raymond Tan and Alvin Culaba from De La Salle University and Professor Jose Cruz Jr., formerly from the Ohio State University.

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Kathleen B. Aviso is currently an associate professor in the Chemical Engineering Department and a researcher at the Center for Engineering and Sustainable Development Research (CESDR) at De La Salle University, Manila, Philippines. She received her BS in Chemical Engineering (cum laude) from the University of the Philippines-Diliman in 2000. She completed her MS in Environmental Engineering and Management (with high distinction and the outstanding master’s thesis) in 2006 and her Ph.D. in Industrial Engineering in 2010 from De La Salle University. She received the 2008 Outstanding Scientific Paper Award from the Philippine National Academy of Science and Technology (NAST) and recently won the 2010 NAST Talent Search for Young Scientists. Her current research work focuses on the use of quantitative techniques for designing schemes of efficient use of water in industrial ecosystems. She now has 10 published and forthcoming papers in ISI-indexed journals. E-mail at [email protected].