Stress is measured by the per capita availability of water. This per capita rate will vary from country to country or across cultures. When the fresh water availability is around 1700 cubic meters water stress begins and when this amount reached 1000 cubic meters, it begins to affect the economic development and health of nations.
Reasons leading to water stress
The current world population is estimated to be around 7 billion. By 2050, the estimated population is believed to reach around 9 billion. Most of this increase in population is taking place in the Asian and African countries. These countries are likely to face the maximum stress on water unless they are able to sustain and manage their water availability.
The rapid urbanization that is happening all over the world, also puts stress on water availability. Since the population in cities are concentrated in a smaller area, it is not possible to have small private wells or septic tanks. Hence large investments are required to provide clean water and also to remove waste water for recycling. Business activities including industrialization and tourism also requires water in large quantities adding to the stress on the available water supply.
c. Climatic changes
This is one of the most serious problems facing the world today. All water available on earth goes through the hydrologic cycle or water cycle. Water keeps moving all the time. It moves from smaller rivers and lakes to bigger sea or ocean and from the ocean to the atmosphere. It goes through various processes line evaporation, condensation, precipitation etc. The amount of available water remains constant. This increase in temperature (also known as global warming), will lead to greater evaporation and changes in precipitation which will cause regional changes in the availability of fresh water. Frequents floods and droughts are another fallout of this phenomenon. A higher percentage of melting of snow and ice has also been noticed. All these events will affect the quality and availability of fresh water.
d. Depletion of aquifers
Aquifers are found below surface layers and are mostly made of permeable and porous rocks. A large quantity of water is available here. This ground water is pumped up through various pumps throughout the world and some cities and countries have started experiencing stress because of this excess extraction of water from below.
There are many pollutants affecting the fresh water supply. The major pollutant is the untreated sewage water, which flows directly into the sources of fresh water. This happens mainly in developing countries. Industrial wastes and chemicals from agriculture and industry also find their way into water bodies polluting them. Storm water and treated sewage are also major pollutants.