Seite - 16 - in options, Band summer 2018

www.iiasa.ac.atoptions ◼ summer 201816 make an effort to improve water use and regulation, and there will be rapid technology change. Depending on socioeconomic growth, water demand is likely to increase. On the other hand, we assume water use efficiency will improve, thus alleviating rapid water demand growth. We created storylines for each scenario with the stakeholders,” says Satoh. They selected three comparable combinations as water use scenarios, dubbed ‘sustainability’, ‘middle of the road’, and ‘regional rivalry’. Each of these narratives was translated into quantitative measures and used to build the scenarios into the modeling framework. In the scenario development process, a unique method, called hydro-economic classification, was applied. Countries and regions were categorized into four groups, based on their likely water scarcity problems and their ability to cope. Then, what the researchers considered to be reasonable assumptions were made. For example, a rich country with high levels of water scarcity will be better placed to cope than a poor one. “Using three global hydrological models we projected water consumption and demand. The models also project the available water resources (supply). Using the framework, we assessed water scarcity for each scenario, using a number of indicators,” says Satoh. “We projected how many people might be affected and how the hydro-economic classification for each country might change over time.” Not a pretty picture Overall, three scenarios project that the population under severe water scarcity in Asia will increase by 38-68% compared to today’s levels. As a whole, water scarcity will increase in 74-86% of regions in Asia depending on the scenario, with some 40% of the continent’s population facing severe water scarcity in the 2050s. Under the middle of the road scenario, by 2050, 20% of the land area of Asia, with a population of 1.6–2 billion people, is expected to be facing severe water scarcity. Climate change has long been accepted as the major cause of water scarcity, but some of the results surprised the researchers. “One of the biggest findings in this study is that demand change can be more significant than climate change over many parts of Asia,” says Satoh. This is the first time that socioeconomic changes have been identified as the main driver of water scarcity. Water demand for agriculture, industry, and households will increase by 30-40% by 2050 compared to 2010. By the 2050s, water demand in Asia is projected to be larger than all the other continents of the world put together. As a result of socioeconomic development in Asia, industrial water demand will rise by at least 136% depending on the scenario, while municipal water demands will rise by a minimum of 176% and up to 245%. Agriculture remains the largest user of water. Seasonal variations, such as extra irrigation in the dry season, further exacerbate the problem of water scarcity in Asia. However, even under the middle of the road scenario, a fifth of Asia will experience severe water scarcity in every season. Regional variations Of course, not all regions will be equally affected. According to the model projection, the areas with the most pronounced water scarcity in 2050 will be the same as now–Afghanistan, China, India, and Pakistan. The impacts of water demand increase are particularly pronounced in areas with megacities, such as northern-, coastal-, and southern China. East and South Asia will see the largest growth in water demand by 2050, accounting for 80% of water use. Growing incomes, increased per capita water use, population growth, and urbanization, will particularly cause a rise in China, India, Indonesia, and Pakistan. In contrast, under the sustainability scenario, areas including eastern Australia, Malaysia, and Myanmar will see lowered water scarcity. According to the hydro-economic classification used by the researchers, the most vulnerable countries will be Afghanistan, Azerbaijan, and Pakistan due to their lower economic ability to cope with the challenges of water scarcity. What now? The researchers designed their scenario-based approach to provide important insights to policymakers on the scale of the potential problem of water scarcity. The initial target of the study was decision makers and investors in Asia, but Satoh says that the findings of the study will be of interest and relevance to any decision makers looking at water use on a global scale. He believes the projections relating to water demand will be particularly useful to decision makers and investors who currently only have supply projections. The results, the researchers say, highlight the clear need for more work on water demand and its management. While water availability is to a certain extent determined by weather patterns, as technology advances, we would be able to do more. Desalination and water transfer are two options Attribution ratio of increases in the withdrawal to availability ratio for supply side (a), and demand side (b). A value of 0 indicates no impact of that factor on water scarcity, while a value of 1 indicates that water scarcity is totally driven by that factor. (Satoh et al, 2017)