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Although fresh water is abundant at a global level, only a tiny amount, less than 0.3 %, is easily accessible for human use (Dinar et al., 2007). An increasing amount of this water is utilized, with global water withdrawals tripling since 1950. Presently, 70 % of the world’s population lives in countries that withdraw more than 40 % of the available water resources. If current trends continue, by 2025 up to a third of humanity will be living in countries in regions where water withdrawals exceed 60 % of the amount available (Shiklomanov, 2003). At these levels of withdrawal there will be insufficient fresh water to maintain many existing natural habitats, and inhabitants will face acute water shortages, especially in times of drought. |
