A recent CIA report stated that in the next decade or so, nearly half of the world's population will live in countries whose ...
KTEH Public Television and Sony Pictures Television
Original program ©1997 Public Television Station KTEH. All rights reserved. A Co-Production of Trans Pacific Television and KTEH. Courtesy of KTEH Public Television and Sony Pictures Television. Teachers' Domain version ©2006 WGBH Educational Foundation. All Rights Reserved.
The causes of water scarcity in Israel are both natural and human-made. Israel has a Mediterranean climate, which is characterized by long, hot, dry summers and short, cool, rainy winters. Like most areas on Earth — dry or not — it is prone to periods of drought. However, Israel is also a growing nation with a rising standard of living. These conditions have placed an increased demand on groundwater for domestic uses.
Israelis are vigilant with regard to conserving water and making the tight supply they have more productive. Given that nearly 80 percent of irrigation water evaporates or seeps into the ground before it can be drawn up by plant roots, it is easy to recognize the importance of one Israeli innovation: drip irrigation. Using this technique, relatively small amounts of water are delivered directly to plant roots. This saves up to one-third of the water that would otherwise be lost during spray applications and enables farmers to double harvests using the same amount of water.
Israel is also a world leader in wastewater recycling, or reclamation, which now accounts for about 30 percent of its total supply. Reclaimed water, sometimes called grey water, is used for a wide variety of purposes. The vast majority of water is used for industrial purposes, such as cooling, and irrigation, and does not need to be pure. By recycling urban waste water for irrigation, Israel not only saves precious groundwater, but prevents the environmental damage caused by the discharge of waste water into rivers and the sea.
Still, over-reliance on recycled water can cause problems, especially in agriculture. Some freshwater sources, like rivers, contain high levels of dissolved solids. Impurities such as those that come from wastewater sources can remain in the water after recycling and slowly build up in the soil. Salt is the primary concern, as it adversely affects crop yields. Unfortunately, purifying water any further is prohibitively expensive.
- What is meant by "laundering" water? What is the source of laundered water? How is laundered water used?
- What is drip irrigation? What are the advantages and disadvantages of drip irrigation?
- What do you think the consequences would be if water were unavailable for agriculture in a region of the world?