| This analysis was carried out separately for every country.
Clear analogies were found in groups of countries with similar GNP-levels, showing that
trends in irrigation depend on population number and GNP-values. The limiting factors are
sufficient area of land suitable for irrigation and the value of the water resource
accessible for use. To estimate the future irrigation water demands, consideration was
given to the tendency for this to decrease because of improved technological procedures
and engineering directed towards economising on the use of water. Estimates of
industrial water withdrawal were based on the dynamics of industrial production in
different regions of the world, including those with different levels of economic
development located in different physiographic conditions. Calculations for current and
future periods were carried out separately for thermal power from other industries with
considerately different trends, rates of development and water losses. In summary, total
water consumption by thermal power engineering was assumed to be 1-4% and for other
industries it was taken as 10-40% of water intake, depending on the development level, the
availability of water supply systems and climatic conditions. |
|
An assessment for the future up to 2025 was made for every
country taking account of special UNIDO (1995) developments. These developments were based
on the analysis of the current situation in the world and the forecast GNP values. As a
result, increased industrial water withdrawal was predicted for 2025, compared with 1990,
for all principal countries, with considerably different scenarios for global development
and electric power generation. We based our figures on the most optimistic development
scenario (Global Balance) for average growth in the level of electricity generation. In
accordance with the UNIDO scenario, water demand is expected to increase 1.4-2.9 times for
developed countries and by 3-10 times for developing countries. Additional water losses
for evaporation from reservoirs were calculated for all the principal reservoirs of the
world, i.e. those having a volume of more than 5 km3, by the difference between average
evaporation from a water surface and the land. The initial data on reservoirs (area,
volume, location, years of construction and other features) were taken from international
monographs as well as from other publications on individual countries and regions. The
evaporation norms for water and land surfaces were determined from the charts in the Atlas
of World Water Balance. |
