I had been to the Big Easy once before. It was exactly one year before Hurricane Katrina and it was to cover another storm, Hurricane Ivan, a category 4 monster that spared New Orleans by veering 200 miles east. On that occasion we arrived on one of the last flights before Louis Armstrong International Airport was shut, drove into the city on Interstate 10 past a 15-mile traffic jam of evacuees heading in the other direction, and stayed in a hotel overflowing with residents who had abandoned their homes for the higher floors of the Comfort Suites on Tulane Ave. As the skies darkened, so did the mood of the deserted city. In the crowded lobby there was muffled talk of previous storms that had flooded New Orleans and the surrounding Gulf Coast. The people of Mississippi and Louisiana tend to be on first name terms with the hurricanes that have visited them. Betsy (1965) and Camille (1969), the meteorological superstars of recent memory, were being discussed with intimate horror as though they were predator relatives.

New Orleans was lucky to dodge Ivan in 2004 and it almost looked as if its luck would be repeated in 2005, because Katrina's eye did not pass directly over the city. But this storm did whip up Lake Ponchitrane and the Mississippi to deliver the nightmare scenario: a storm surge of 20 feet and more that broke the levees. On Tuesday, August 30 the 80 per cent of a city that lies below sea level filled like a bathtub. In the Lower 9th Ward, the lowest – and poorest – neighbourhood, the wave was so strong it ripped the levee wall to shreds and flattened every house for half a mile. Even today, a giant, rust-coloured Mississippi barge sits on top of a yellow school bus, next to a warehouse that looks like something out of a closed pop-up book. In drier times, New Orleans was the only place I knew where you walked along the banks and looked up at the river.

The power of water took most people by surprise. It shouldn't have. Unlike earthquakes, hurricanes provide ample warning, and opportunity for evacuation. And because of its perilous location, New Orleans had even war-gamed a fictitious “Hurricane Pam” two years ago. The conclusion then was that a category 3 hurricane would have disastrous consequences for the city. Katrina was a category 4, and yet Ray Nagin, the outspoken, charismatic mayor of the Big Easy, ordered a mandatory evacuation only one day before the storm made landfall.

Dubious distinction

The second phobia was the very legitimate fear of losing his SUV to thieves. The car radio was hyperventilating with reports of armed gangs, murders, rapes and pitched battles between police and looters. (Well, New Orleans had previously earned the dubious distinction of being “the murder capital” of the USA.) The radio chimed perfectly with the cacophony outside: Blackhawk helicopters swooped overhead, crowds of angry civilians near the now infamous Superdome demanded to know when buses were going to evacuate them. Policemen screamed at soldiers. Soldiers screamed at relief workers. A woman, who had visibly soiled herself, knelt on the Interstate, screaming at the sky. In this bedlam no shots were fired and no punches were thrown, but New Orleans seemed like a city unhinged.

We stopped a group of National Guardsmen and asked them the best way to reach Canal Street, where I had hoped to meet up with colleagues. “There is no safe way, sir. Leave this city. Now! It is not safe! It is NOT safe – there are areas where we don't dare to go.” The high-pitched squeal seemed at odds with the well-armed square-jawed Louisiana guardsman making it. Don and I didn't know what was more perilous: to stay among people who were fast approaching boiling point, or to venture into the no-go areas of New Orleans. We carried on, driving gingerly down streets which were strewn with hurricane wreckage: torn aluminium siding, tree branches, power lines like tangled fishing nets, a Chevrolet crushed by a discharge of bricks, a dead man lying face down in front of an ATM machine.

On the corner of Poydras Street and S Broad Ave the movie experience turned acutely and alarmingly into reality TV. We were suddenly faced by two heavily armed and armoured SWAT teams, who emerged from either side of the street like a troupe of extras converging on a stage. “Get out, get out!” they shouted, pointing their guns first at us and then at the unseen enemy in the buildings beside us. “Looters on the roof!” The Darth Vaders looked scared and that scared us. I turned to see Don fiddling awkwardly under his seat. Like a rabbit conjured out of a hat, his own weapon appeared in his hand. “These guys don't know what they're doin',” Don pronounced with his customary drawl, cocking his Magnum. “I'm gonna be mountin' my own defence.”

Oh for the mayhem of Terminal 4. I thought I had come to cover a weather story, but in New Orleans that day something entirely different was unfolding. It was a battle between fact and fiction, reality and rumour, fear and sanity. In the absence of working mobile phones and wireless communications, everyone was struggling. Even the military was reduced to employing “runners”, last used in the Civil War. Ironically the city's few remaining pay phones, abandoned relics in the era of mobile technology, were working perfectly and experienced a brief resurrection. A colleague from The Daily Telegraph resorted to sitting on a stranded armchair in the middle of Canal Street, juggling quarters and dictating his story to a copytaker in London. Everyone was floundering and improvising. What surprised my colleagues and me is that the authorities – city, State and federal – floundered longer and improvised less than most. With the skies full of helicopters, 60,000 men under arms advancing on a rapidly emptying city, and aircraft carriers replacing steamers on the Mississippi, the superpower was getting into gear with the nimble dexterity of a supertanker.

There was something medieval about this Venice from Hell. Stranded citizens in various states of disrepair and distress, like the damned in a Hieronymus Bosch painting, littered the pavements. The smell of rotting food and putrid water was trumped here and there by the stench of a decomposing body. Outlandish rumours appeared plausible in a place where the bizarre had become normal. For instance, reports that children and babies had been raped careened through the ranks of evacuees and were then “confirmed” on the Oprah Winfrey Show by a tearful Eddie Compass, the police chief. He is the same man who told me that Katrina and the breaking of the levees was God's wrath for the sins of his city. With chiefs like him, it's not surprising that fear and fantasy ruled the day.

The most obvious example of this was the Convention Center. An ugly modern complex that stretches along the banks of the Mississippi for more than a mile, the Center is a cathedral of conference tourism. In the months before Katrina it had accommodated software experts, facial reconstruction gurus, and the Canadian Association of Nurses for their annual get-together. In the first week of September it became a mass convention of misery. Perhaps 8,000 residents – no one knows the exact number – had crowded in and around the complex. The vast majority were poor and black. They had not left the city for a variety of reasons. Sam Nutting and his family did not possess a car.

A dastardly plot

In September 2005 there was no evidence of any sinister plot. Personally I saw no evidence of overt racism. But there was plenty of mistrust between black and white and good deal of incompetence. For instance, the authorities and the rumour mill had told people to flock to the Convention Center for safety and evacuation, and then abandoned them to their own resources. I arrived there on Thursday afternoon. Most of the people had been there since Tuesday. Officials from the American Red Cross, FEMA – the disaster relief agency – or any other arm of government were conspicuous by their absence. Occasionally armed men in uniform appeared, standing on the back of pick-up trucks, their guns held aloft as if they were on a hunting trip. Were they local police, officers from other municipalities, vigilantes, white looters? They didn't enlighten us. Many sported red bandanas and smoked cigars, which, to be frank, didn't enhance their image as potential care providers. I saw one elderly couple being told to “Back off ” when they approached with a perfectly reasonable question: “When are we going to get out?” No answer from the men with red bandanas. Just another warning: “Back off!”

The other manifestation of officialdom came from the skies. Every half-hour a helicopter would appear, hover above the empty car park next to the Convention Center and dump a few crates of water. This triggered a scrum in which the young and the aggressive would invariably get hold of the water, leaving everyone else at their mercy. Any aid official will tell you this is one way to turn a crowd of waiting evacuees into a riot. But in New Orleans there was no riot. Instead there was resignation and utter helplessness. I will never forget the pained, vacant stares of the ageing residents of the Gus Tyler Nursing Home, lined up in their wheelchairs like front row spectators in Hell. After three days and nights of being rooted to their metal chairs in the sweltering heat without food, medicine or water, all had soiled themselves, many were fading into a feverish delirium and five had died. We were shown the bodies of two elderly women, still slouched in their wheelchairs. Why these people had to wait for several days for buses that were parked a few miles away remains baffling.

One explanation was that the bus drivers were too afraid to come to the Convention Center, which officials had convinced them was on the point of eruption. Another was that the arrival of soldiers might trigger a race riot. According to yet another, the streets were too dirty and had to be swept clean before the school buses dared to park in front of the Center. A middle-aged man came up to me and said he had organised 50 qualified drivers who were happy to drive the buses themselves, if only they could be taken to the vehicles. I had no answer for him. Nor, clearly, did the authorities. But despite the desperate state of 8,000 people, there was less evidence of violence in the New Orleans Convention Center than there is at closing time outside the Hat and Stick near Broadcasting House.

Americans expect the devastation of hurricanes. They did not expect the shambles and chaos that followed. Events in New Orleans dominated every newspaper and television channel. The networks stopped pulling their punches. The usually understated Economist thundered “The Shaming of America” on its cover, and even the flag-waving Fox TV – owned by the same Rupert Murdoch who criticised the BBC for its “anti-American” coverage – sounded a note of jaw-dropping disbelief. At the time of writing, the death toll for the whole Gulf Coast stands at 1,200. This is a lot lower than the 10,000 predicted at one stage by the mayor of New Orleans, but still one of the worst natural disasters in modern American history. Crucially it is estimated that 700 people – most of them elderly – died after the initial storm as a result of neglect or mismanagement. These were the deaths that could and should have been avoided. Why they were not will continue to be the subject of bitter debate.

A despised four-letter word

All the above blamed the President for failing to get off his ranch quicker and do what he prides himself on: managing a crisis. One possible explanation for his lacklustre performance emerged after the waters had receded. When Katrina crashed into the Gulf Coast, Karl Rove, George W. Bush's most trusted lieutenant, was absent from the White House, confined to hospital suffering from kidney stones. Distracted by excruciating pain he was unable to advise his master. Whatever the reason, Katrina turned out to be a huge blow for the President. It raised questions of competence, even among those who agree with Bush on matters of values and ideology. The storm broke the levees of the President's credibility.

The only agency to emerge blameless from the storm was the Coast Guard, whose red helicopters rescued thousands of citizens from trees and rooftops. But such was the shock and soul-searching triggered by Katrina that this was a crisis without the usual mythology of heroes. Even belated attempts by the networks to celebrate the Coast Guard as “the heroes” of Katrina fell on deaf ears because America was tearing its hair out over much bigger questions raised by savage weather. If the authorities can't handle a hurricane, what will they do if a dirty bomb hits Washington? Where is the scientific and political debate about the increasing strengths of hurricanes? Is the “greatest democracy on earth” best served by a layered system of government that is at best devolved and at worst messy? Is the superpower too big to micro-manage a domestic crisis caused by a hurricane named Katrina?