21
7. WATER RESOURCES
World water resources are composed of oceans, seas, lakes, rivers, snows and
glaciers and ground waters. World total volume of water is 1,398,898,300 km 3. Entire
amount is not available to be used. About 97% of this volume is saline water in oceans
and seas and not available to be used for domestic, industrial and agricultural purposes.
About 1.7% is in the form of ice in glaciers and ever-melting and mixing with saline
seas and oceans. About 0.8% is not able to be reached for various reasons and
constitutes ground waters. Remaining 0.2% is in the form of gas in atmosphere. Spatial
distribution of water resources is not homogenous worldwide. While the South
American countries have the richest water resources, African and Middle East countries
have the poorest resources.
This section of the report briefly highlights the state of water resources in the
COMCEC Member Countries In this report, a distinction has been made between
renewable and non-renewable water resources. Renewable Water Resources (RWR)
implies the water resources generated from endogenous precipitation. They are
computed on the basis of the water cycle by adding up the long-term average annual
flow of rivers and lakes (surface water) and recharge groundwater reservoirs. Total
Renewable Water Resources (TRWR) are the total amount of a country’s water
resources and defined as the sum of Internal Renewable Water Resources (IRWR) and
External Renewable Water Resources (ERWR), i.e. the incoming flows originating
outside the countries’ borders.
Water is a scarce resource in arid and semi-arid regions where many COMCEC
Member Countries are located, particularly in West Asia and North-eastern Africa.
Therefore, most of the COMCEC Member Countries in these regions are facing severe
pressures due to limited opportunities for the exploitation of new water resources. These
pressures are expected to increase in the face of expanding population and the increased
per capita water use associated with economic development, as well as due to the
expected negative impacts of climate change in the future.