Water scarcity

Water scarcity (closely related to water stress or water crisis) is the lack of fresh water resources to meet the standard water demand. There are two types of water scarcity: physical water scarcity and economic water scarcity. Physical water scarcity is where there is not enough water to meet all demands, including that needed for ecosystems to function. Arid areas for example Central and West Asia, and North Africa often suffer from physical water scarcity. On the other hand, economic water scarcity is the result of a lack of investment in infrastructure or technology to draw water from rivers, aquifers, or other water sources, or insufficient human capacity to meet the demand for water. Much of Sub-Saharan Africa has economic water scarcity.

There is enough freshwater available globally and averaged over the year to meet demand. As such, water scarcity is caused by a mismatch between when and where people need water, and when and where it is available. The main driving forces for the rising global demand for water are the increasing world population, improving living standards, changing consumption patterns (for example a dietary shift toward more animal products), and expansion of irrigated agriculture. Climate change (including droughts or floods), deforestation, increased water pollution and wasteful use of water can also cause insufficient water supply. Scarcity varies over time as a result of natural hydrological variability, but varies even more so as a function of prevailing economic policy, planning and management approaches.