The volume of global freshwater resources on the Earth is around 35 million km3, or only about 2.5% of the total water volume equal about 1.4 billion km3 (UNU, 2013), and freshwater scarcity is increasingly perceived as a global systemic risk. Addressing new demands for fresh water and the ecosystems protection through provision of their maximum sustainable levels per catchment is the most difficult and important challenge of this century (Mekonnen & Hoekstra, 2016). It is obvious that due to steadily increasing demands a freshwater scarcity is becoming a threat to sustainable development. In its most recent annual risk report, the World Economic Forum (WEF, 2015) lists water crisis as the largest global danger in terms of potential impacts. For the first time, a water crisis has been also considered as a main climate change challenge at the Conference of Parties (COP) to UNFCCC that took place in Marrakech in late 2016.