UNITED NATIONS Intensive damming and drainage of the Tigris and Euphrates rivers has transformed the southern Iraqi marshland at the heart of the fertile crescent into a salt-encrusted wasteland, a UN study said on Friday based on newly released satellite images.

The images show that some 90 percent of the vast wetlands region -- best known for its role as the Middle East's cradle of civilization some 10,000 years ago -- has disappeared due to the building of more than 30 large dams over the past 40 years and huge drainage projects carried out after the 1991 Persian Gulf War, said the new study by the United Nations Environment Program.

Based on historical records and satellite photos taken by the U.S. space agency NASA, the study found the wetlands, which once covered 5,800 to 7,700 square miles (15,000 to 20,000 sq.kms.), have now shrunk to just 580 to 770 square miles (1,500 to 2,000 sq.kms.).

Reuters reported that the satellite images were taken in 1992 and 2000, and were part of a gift of 16,000 images recently given to UNEP by NASA and valued at $20 million. More than half of them had never been seen or analyzed by the scientific community before the UNEP study.

The area has been difficult to monitor due to Iraq's isolation since the Persian Gulf War, when a U.S.-led coalition drove it out of Kuwait after its 1990 invasion.

"The satellite images provide hard evidence that the once extensive marshlands have dried up and become desert, with vast stretches salt-encrusted," the UNEP study said.

Small Northern Fringe Remains

"A small northern fringe of the Al-Hawizeh Marsh, straddling the Iraq-Iran border and known as the Hawr al-Azim in Iran, is all that remains," the study said. "Even this last vestige is rapidly disappearing as its water supply is impounded by new dams and diverted for irrigation."

Local wildlife has also been badly damaged and the loss of wetlands is threatening to stamp out the 5,000-year-old culture of Iraq's marsh Arabs, about a fifth of whom now live in refugee camps in Iran while the remainder are scattered across the Iraqi countryside, UNEP said.

Due to the environmental damage, the smooth-coated otter is considered extinct, some 40 species of waterfowl and migratory birds from Siberia to South Africa are threatened and fish populations in the northern Persian Gulf -- which depend on the marshlands for spawning grounds -- have experienced sharp declines, UNEP said.

"The collapse of marsh Arab society, a distinct indigenous people that has inhabited the marshlands for millennia, adds a human dimension to this environmental disaster," it added.

Possible to Save Wetlands

Despite the extent of the damage, UNEP insisted it was still possible to save the threatened wetlands and called on Iran, Syria and Turkey as well as Iraq -- all nations dependent on the marshlands and the rivers that feed them -- to agree to a recovery plan.

Such a plan would have to reevaluate the role of river damming and modify existing dams where necessary to reinstate managed flooding in the region over the long term, UNEP said.

The four countries must also do a better job of managing available water resources, UNEP said, urging them to adopt an international agreement on sharing the waters of the Tigris and Euphrates "for the benefit of people and nature and to ensure an adequate water supply to the marshes."

UNEP said it was carrying out a scientific assessment of the Tigris-Euphrates basin to help improve water management practices.