Post a comment on the text below

Box 4.3  Indicators for defining sustainability in water use

Setting a global threshold in identifying sustainable use of water resources is a scientifically challenging topic. For the time being, overall, three different indicators are widely implemented in defining whether actual water use is sustainable or not. These indicators are:

• environmental flows indicating critical stages and discharges. In principle, methods for defining e-flows can be classified in four major categories: hydrological methods; hydraulic rating; habitat simulation models; and holistic methodologies (Zeiringer et al., 2018). An inventory by Ramos et al. (Ramos et al., 2018) reveals that in most cases where environmental flows have been derived were mainly developed based on hydrological methods. This means a static or dynamic fraction of the mean annual flow is defined as environmental flow without making an explicit link with ecological variables. Also, most of the respondents do not differentiate the environmental flows between dry and normal years. Critical stages/discharges of rivers and artificial canals; environmental flows (e-flows), defined as minimum flow requirements using hydrological and hydro-ecological methods (EC, 2016)
• Critical levels of water stress e.g. Water exploitation index (Raskin and Gleick, 1997). The indicator takes 20 % of water abstraction from water availability in the environment as indication to water stress.
• Critical levels of droughts, applying a set of available drought indicators (e.g. SPI)