Wheat fields, rice paddies and fruit orchards have been deluged to a depth of up to 10 feet, Dr Hussain Shahristani of the Gulf war Victims human rights group told the Independent on a brief visit to London.
Water has proved a double- edged sword for the Iraqi leader. For nearly a year, President Saddam has sought to drive out from the Huwaiza marshes the remnants of the resistance that rose up against him in the south after the end of the Gulf war in the spring of 1991.
His main method in the past was to drain the marshes, destroying their unique centuries-old water-borne culture by diverting the waters of the River Euphrates into his ambitious drainage canal known as the Third River Project. The Huwaiza marshlands form a triangle of land linking the main centres of Al-Amarah, An-Nasiriyah, and Al-Qurna.
People who for generations had based their way of life on water were transformed into nomads in search of water.
Now President Saddam is showing that he can turn a tap on as well as off. He has diverted the waters of the River Tigris, which usually does not flood until early April, to swamp the smaller area south- east of Al-Amarah around the main centres of Al-Musharah, Al-Kahlah, and Qalat Salih to continue his campaign to purge the country of those behind the uprising in the Shia Muslim south of the country in and around Basra.
According to Dr Shahristani, tens of thousands of people have been displaced by this latest move. Schools have been abandoned, and livestock killed. Many farmers have tried to make it across to Iran, where Dr Shahristani and other aid groups provide them with limited shelter.
'This is a clear attempt at genocide against the southern Iraqis,' Dr Shahristani said, 'to punish them for the uprising of Basra.'
Most of the resistance has now moved further south to another network of marshes, at Hor al-Hammar, which cannot be drained because President Saddam's new drainage canal flows into it.
It was close by at Hor Aluwi that there were reports last autumn that Iraqi forces had used chemical weapons to suppress the resistance.
No clinical evidence has been produced to back up the hearsay and eyewitness accounts of white clouds of smoke and birds falling out of the sky. Dr Shahristani, who trained as a chemical engineer, said that the gas used by the Iraqi forces was phosgene, which is a very unstable substance that is quickly dispersed. Against the Kurds, during the Anfal extermination campaign, Iraq had used the far more toxic nerve gases sarin and Tabun, which survive far longer in the soil. As a result traces of the poisons could be found for some time after the event.
Dr Shahristani, a Shia from Kerbala, was formerly employed as chief scientific advisor to President Saddam's nuclear energy development programme. He fell out with the Iraqi leader in 1979 when he discovered that his master was bent on pursuing a programme to develop or procure nuclear weapons.
He was put away in the Abu Ghraib prison outside Baghdad where he languished for 11 years in solitary confinement, until he escaped during the mayhem that followed the coalition assault on Iraq during the Gulf war.