Seite - 17 - in options, Band summer 2018

www.iiasa.ac.at summer 2018 ◼ options 17 to artificially enrich local water supply. Desalination becomes ever cheaper and more efficient, and already supplies water to some water-stressed areas of the world, although it is only useful in coastal regions and is dependent on socioeconomic conditions. Water recycling technologies and schemes are also important. Improving water management, such as better planning in reservoir operations and adjusting irrigation periods in agriculture, play an important role in regions that have significant seasonal variability. Managing demand is still the most important tool available to reduce scarcity, as well as the imbalance between water supply and demand. All sectors will need to reduce losses and improve water use efficiency. For example, agriculture uses most of its water in irrigation, of which there are three main forms–flood, sprinkler, and drip. Drip irrigation is the most efficient, but also the most expensive. Satoh and his colleagues assume that due to economic growth in Asia, it will become more affordable, and they expect that the higher efficiency system will eventually become dominant. The socioeconomic changes, which lead to increased water demand and are the main driver of water scarcity, will need better management and policy interventions through, for instance, better governance and investment in technology and facilities. The answer to the question posed in the headline then is–not necessarily. “The message of this study is that we need to change our water use practices, as it has huge impacts on water scarcity. Although climate change is going to affect or intensify water problems, we may be able to adapt or change the situation by changing ourselves. A good recent and topical example was Cape Town in South Africa, which avoided “Day Zero” when water would have been cut off, by people and the city significantly reducing their daily use and demand,” says Satoh. HT More info: Satoh Y, Kahil T, Byers E, Burek P, Fischer G, Tramberend S, Greve P, Flörke M, et al. (2017). Multi-model and multi-scenario assessments of Asian water futures: the Water Futures and Solutions (WFaS) initiative. Earth’s Future 5 (7): 823-852. [pure.iiasa.ac.at/14608] Yusuke Satoh satoh@iiasa.ac.at Withdrawal to availability ratio in the 2010s (a) compared to the projected ratio in the 2050s under each scenario (b1-3). In (c), blue indicates a continual decrease in the ratio, red a continual increase, orange a decrease for three decades followed by an increase, and light blue indicates an increase for three decades followed by a decrease. (Satoh et al, 2017)