3.3.3 - The Hydrosphere (KQ3): Water Supply in Arid Countries

Issues and Solutions

  Water resources in arid & semi-arid areas are very scarce due to the low rainfall and high evaporation. This complicates the supply of water for domestic, industrial, and agricultural uses. Increased demands on our groundwater resources have overstressed aquifers in many areas of the US, not just in arid regions. Groundwater may be an alternative or supplemental source of water during periods of surface-water drought, if sufficient groundwater resources exist.

·         Reduced groundwater levels due to drought or increased pumping during drought can result in decreased water levels and flows in lakes, streams, and other water bodies.

·         Desalination or desalinization is a process that removes minerals from saline water. The Middle East is one of the driest places on the planet. Water desalination has been practiced for more than 50 years in the region and has become the primary response to water shortage in several countries. The region accounts for almost half of the global desalination capacity with Persian Gulf states having the largest share.

·         There are three main methods of desalination namely thermal, electrical, and pressure. These methods differ in terms of energy consumption, cost and whether they can be used for seawater or brackish water treatment. The three most common desalination technologies in the region are multistage flash (MSF), reverse osmosis (RO) and multi-effect distillation (MED) (click the links to learn about each).

          Watch the following video that explains the process of RO desalination visually.

   Case Studies

·         Malta has no rivers or lakes; 68% of Malta’s water comes from groundwater which is being exploited at a rate of almost 50% over and above sustainable extraction levels. The balance comes from seawater desalination, which consumes 7% of all the electricity used in the country, all of which comes from the burning of fossil fuels in power stations. Malta gets its water from two sources: groundwater and three reverse osmosis (RO) desalination plants. At present, groundwater still accounts for 43% of the potable water supply; the balance comes from the RO plants.

·         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.

·         Among industrialized countries, the United States is one of the most important users of desalinated water, especially in California and parts of Florida (there's a BIG one in Tampa!). The cost of desalination has kept desalination from being used more often.

           Israel is a world leader in desalination and water reuse, and has really made a big comeback from a massive water shortage...which could aid in easing tensions in the region.  Watch the following video on Israel's techniques.

Adapted from Miami Killian Sr. High