— Ch. 1 · Defining Water Scarcity Types —
Water scarcity.
~4 min read · Ch. 1 of 7
In 2007, the International Water Management Institute published a study that distinguished two distinct forms of water scarcity. One form is physical water scarcity, which occurs when natural resources cannot meet all demands including those needed for ecosystems to function. Regions with desert climates often face this type of shortage. Central Asia and North Africa serve as examples of arid areas where physical scarcity prevails. The other form is economic water scarcity. This results from a lack of investment in infrastructure or technology to draw water from rivers or aquifers. It also reflects weak human capacity to meet water demand. Many people in sub-Saharan Africa live under conditions of economic water scarcity. They must travel long distances to fetch unclean water for household use.
Global Measurement Indicators
Malin Falkenmark developed an indicator called the Falkenmark Water Stress Indicator to quantify regional water availability. This metric states that a country experiences water stress when annual supplies drop below 1,700 cubic meters per person per year. Levels between 1,700 and 1,000 cubic meters lead to periodic shortages. When supplies fall below 1,000 cubic meters per person annually, the nation faces water scarcity. A report by the Food and Agriculture Organization in 2018 defined water stress as the ratio between total freshwater withdrawn and total renewable freshwater resources. Environmental flows are water flows required to sustain freshwater and estuarine ecosystems. Experts now use more complex models since the early 2000s. These include green-blue water scarcity assessments and footprint-based water scarcity evaluations. Such tools benefit from spatial analysis capabilities.