water stress


A country is water stressed if the available freshwater supply relative to water withdrawals acts as an important constraint on development. In global- scale assessments, basins with water stress are often defined as having a per capita water availability below 1,000 m3/yr (based on long-term average runoff). Withdrawals exceeding 20% of renewable water supply have also been used as an indicator of water stress. A crop is water stressed if soil available water, and thus actual evapotranspiration, is less than potential evapotranspiration demands. (IPCC)