At least 2.7 billion people live in river basins that experience severe water shortage during at least one month of the year. We need to rethink the way we use water. We are exceeding many of our planet’s limits, but it is the availability of freshwater that will have the biggest impact on future food, water and energy security.
To provide a more refined insight into water availability and demand than is generally considered, a recent study (Hoekstra et al., 2012 ) has analysed the monthly Blue Water Footprint of 405 major river basins, in which 65 per cent of the global population reside.
A precautionary approach was taken based on natural flows (the estimated flow through the river basin before any water is taken out), and the presumed environmental flow requirement (the amount of water needed to maintain the integrity of freshwater ecosystems), assumed to be 80 per cent of monthly natural run-off (Richter et al., 2011).
If more than 20 per cent of the natural flow is being used by people, then the Blue Water Footprint is greater than the amount of blue water available and water stress will occur.
To provide a more refined insight into water availability and demand than is generally considered, a recent study (Hoekstra et al., 2012 ) has analysed the monthly Blue Water Footprint of 405 major river basins, in which 65 per cent of the global population reside.
A precautionary approach was taken based on natural flows (the estimated flow through the river basin before any water is taken out), and the presumed environmental flow requirement (the amount of water needed to maintain the integrity of freshwater ecosystems), assumed to be 80 per cent of monthly natural run-off (Richter et al., 2011).
If more than 20 per cent of the natural flow is being used by people, then the Blue Water Footprint is greater than the amount of blue water available and water stress will occur.
