Officials have vowed to heed the lessons from Katrina in 2005, when about 30,000 evacuees spent days packed inside the sweltering Superdome without electricity or running water. The stadium, whose roof peeled off in the howling wind, allowing rain to pour in, became known as a squalid shelter of last resort.

The fiasco exposed how the city and country did not prepare adequately for the storm.

Senator Chuck Grassley of Iowa told President Donald Trump on Twitter to “keep on top of hurricane Harvey” and not repeat the mistakes that President George W Bush made with Katrina. Bush was heavily criticised for a slow federal government response to the storm, which left more than 1800 people dead and caused $US151 billion in damage.

“Got your message loud and clear. We have fantastic people on the ground, got there long before (hash)Harvey. So far, so good!” Trump tweeted back. Later, the White House announced Trump would go to Texas on Tuesday.

There is no doubt the challenge will be huge for Houston, a city of 2.3 million residents.

Forecasters say the remnants of Hurricane Harvey will dump as much as 1.27m of rain in some spots, the highest ever recorded in Texas. “The breadth and intensity of this rainfall is beyond anything experienced before and is resulting in catastrophic flooding,” the National Weather Service said.

In New Orleans, almost 80 per cent of residents were evacuated days before Katrina’s arrival. In contrast, Houston mayor Sylvester Turner advised people to stay in their homes, saying it was not feasible to evacuate the entire city.

Rescue workers were so overwhelmed with calls for help on Sunday that initially they were able to respond only to life-and-death situations.

The people of Houston are desperate for help right now. pic.twitter.com/UHBng9PJwb

— Trey Yingst (@TreyYingst) August 27, 2017

Harvey throws a wrench into U.S. energy engine https://t.co/wFJ2STGMCs pic.twitter.com/7fNIRmRawy

— Yahoo Finance (@YahooFinance) August 28, 2017

Astounding video shows numerous boats maneuvering around stranded vehicles on flooded street in Dickinson, Texas. https://t.co/YGP3fEVW8t pic.twitter.com/LHM5SbVftF

— Evan McMurry (@evanmcmurry) August 27, 2017

Houston authorities urged people to escape to the roofs of their homes to avoid becoming trapped in attics, which caused more than a dozen deaths in Katrina’s aftermath. Residents were asked to wave sheets or towels to draw attention to their location as floods reached second-storey levels – echoing images from New Orleans.

The number of shelters in Houston was expected to dramatically increase. The George R Brown Convention Center received hundreds on Sunday as authorities scrambled to ready the building. Officials asked for help from restaurants to feed its growing population.

It and the city’s Astrodome in 2005 received thousands of Katrina evacuees fleeing the horrific conditions of New Orleans’ shelters in 2005.

Houston was applauded then for showing how shelters should be run but some people have questioned city officials’ decisions so far in this storm.

Desiree Mallard, who escaped her apartment complex by using an inflated air mattress to float her nearly two-year-old son through chest-high floods, said she wished she had left before Hurricane Harvey approached the Texas Gulf Coast. But she saw on the news to stay in place.

“And then when it got bad, they said it’s too late to evacuate,” she said.

People carry their belongings through flooded roads in League City, Texas. Photo: Stuart Villanueva/The Galveston County Daily News via AP

Asked if this storm could become Houston’s Hurricane Katrina, Texas Governor Greg Abbott, who had contradicted the mayor’s advice and urged people to flee from Harvey’s path, ducked the question.

“As far as the evacuations, now is not the time to second-guess the decisions that were made,” Abbott told reporters in Austin. “What’s important is that everybody work together to ensure that we are going to, first, save lives and, second, help people across the state rebuild. And because of the effort that we’ve been able to put together, I think and believe we will be very successful.”

– AP