One of Saddam Hussein's greatest acts of ecological destruction – the draining of the Mesopotamian marshes – has been reversed as birds and rivers return to the region

Saddam Hussein's draining of the Mesopotamian marshes of Iraq – recorded as the Garden of Eden in the Bible - was one of the most infamous outrages of his regime, leaving a vast area of once-teeming river delta a dry, salt-encrusted desert, emptied of insects, birds and the people who lived on them.

But nearly two decades later the area is buzzing and twittering with life again after local people and a new breed of Iraqi conservationists have restored much of what was once the world's third largest wetland to some of its former glory.

The story of this once almost impossible restoration is told in an exhibition of photographs that has opened in the UK. They show the huge expanses of reeds and open water – now at least half the size of the Florida Everglades – where plants, insects and fish have returned, creating a vast feeding area for migrating and breeding birds, including the majestic sacred ibis, the endemic Basrah reed warbler and the Iraq babbler, along with most of the world's population of marbled teal ducks, bee-eaters and many more.

"We call them stop-over sites, refuelling sites," said Richard Porter, Middle East adviser for the conservation group Birdlife International, who has helped train biologists and other experts for the local Birdlife partner Nature Iraq. "They are as important as the breeding and over-wintering grounds for species; if you have got to make a journey from central Africa to northern Europe and Asia, and you've got nothing to feed on, you're stuffed."

The Mesopotamian marshes originally made up an area more than three times the size of Norfolk, where the exhibition is showing, in Holt. It sprawled across thousands of square kilometres of floodplain where the Euphrates and Tigris rivers divided into a network of tributaries meandering and pulsating south to the Arabian sea. They were home to more than 80 bird species, otters and long-fingered bats, and hundreds of thousands of Marsh Arabs who grew rice and dates, raised water buffalo, fished and built boats and homes from reeds.

In the early 1990s, this way of life came to an abrupt end when Hussein ordered the marshes to be drained to punish the local population for an uprising after his failed invasion of Kuwait, a problem exacerbated by the continued construction of dams upstream.

He ordered the area to be hemmed in by constructing around 4,000km of earthen walls that towered up to 7m above the unbroken flat landscape. The wetlands retreated to as little as 5-10% of their original size, according to a 2001 United Nations Environment Agency report.

After Hussein was toppled by American forces in 2003, Azzam Alwash returned from his adopted home in the US to the area, where he had lived for part of his childhood, and learned to hunt ducks with his father while they inspected the irrigation ditches. Alwash found the local people who had stayed had already begun to break up the walls with shovels or earth diggers, and they have continued to do so. They have destroyed up to 98% of the embankments, he told the Guardian, "not because they are tree-huggers or bird-lovers, but because it's a source of economic income to them, because they can harvest reeds and sell them. They can fish and feed a family or sell them to earn extra income."

Alwash, a civil engineer, set up Nature Iraq and has organised training for graduates who help with monitoring work. "We take guards with us with Kalashnikovs, but the most difficult part is the road between [the capital] Baghdad to the marsh," said Alwash. "Once I'm inside the marshes it's relatively safe."

About half the original marshland has been restored - even more had been reinstated, but there was a setback last year because of a drought. Nature Iraq has now drawn up a plan to cope with the diminishing water flows from dams upstream in Turkey by channelling irrigation water back into the rivers and building a barrage to retain meltwater from the mountains and create a "mechanical flood" of water to replicate the important pulses of freshwater that wash through the marshlands every spring.

Alwash and his team are also trying to tackle the problem of local poaching, although he has great sympathy with those who have few alternative sources of income, and hopes the opening of a new oil industry will help create jobs.

"We have done some work in trying to educate the locals," he added. "We say: 'Go out and hunt but take less; make $10 today – you don't have to make $20, and make $10 tomorrow'. We just keep at it. You can't give up."

• The exhibition runs until July 25 at Birdscapes Gallery in Glandford, Norfolk