Tuesday, September 23, 2008

Iran sinking as groundwater dwindles

National Geographic: Iran's insatiable demand for water, which is being drawn out of aquifers far faster than it can be replenished, is causing large chunks of farmland to sink and buildings to crack, according to a new study. Estimates suggest the water levels in Iranian aquifers have declined by an average of nearly 1.5 feet (half a meter) every year over the last 15 years. As the water is removed, soil and rock lose their support, leading to compaction and sinking.

Satellite radar observations—collected by Mahdi Motagh from GFZ, the German Research Centre for Geosciences based in Potsdam, Germany, and his colleagues—are showing just how serious the problem is. Combining satellite radar images of the land surface dating back to 1997 with water level data, the team has shown that water withdrawal from aquifers is creating a major dilemma.

Much of Iran is very dry, and only 10 percent of the country receives enough rainfall to meet its needs. The remainder of the country is heavily reliant on groundwater, with around 50 percent of Iran's water being supplied by aquifers. Population growth, combined with economic development and a boom in industry and farming, has caused a huge increase in demand for water in Iran, according to Motagh.

But the slow-filling aquifers have not been able to keep up. "Most of the aquifers have recharge times of thousands of years," he said…..

A salt lake in Iran, with some photoshopped color. Shot by Bertil Videt, Wikimedia Commons, under the terms of the GNU Free Documentation License, Version 1.2

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