It is estimated that some 30% of the world’s irrigated areas suffers from salinity problems and remediation is seen to be very costly.
Poor drainage and irrigation practices have led to water-logging and salinization of about 10% of the world’s irrigated lands, thereby reducing productivity.
There are significant areas of the globe where serious soil and groundwater salinization are present or have developed as a result of:
· rising groundwater tables, associated with the introduction of inefficient irrigation with imported surface water in areas of inadequate natural drainage
· natural salinity having been mobilized from the landscape, consequent upon vegetation clearing for farming development with increased rates of groundwater recharge
· excessive disturbance of natural groundwater salinity through uncontrolled well construction and pumping.
Water-logging and salinization in large-scale irrigation projects are often the result of unavailable drainage infrastructure, which was not included in the engineering design in order to make projects look economically more attractive. These problems are generally associated with large-scale irrigation development under arid and semi-arid conditions, as in the Indus (Pakistan), the Tigris-Euphrates (Middle East) and the Nile (eastern Africa) river basins. The solutions to these problems are known, but their implementation is costly.
With population growth and concerns about water scarcity increasing, several countries, especially in the Middle East region, are developing desalination plants to convert saline water (e.g. sea-water, brackish water or treated wastewater) into freshwater.
The global market for desalination currently stands at about US $35 billion annually and could double over the next 15 years.
In 2002 there were about 12,500 desalination plants around the world in 120 countries. They produce some 14 million m²/day of freshwater, which is less than 1% of total world consumption.
The most important users of desalinated water are in the Middle East, (mainly Saudi Arabia, Kuwait, the United Arab Emirates, Qatar and Bahrain), which uses about 70% of worldwide capacity; and in North Africa (mainly Libya and Algeria), which uses about 6% of worldwide capacity.
Among industrialized countries, the United States is one of the most important users of desalinated water (6.5%), especially in California and parts of Florida.
The section “Did You Know…?” is taken from the 1st United Nations World Water Development Report: “Water for People, Water for Life” (WWDR1, 2003)