HOUSTON (NYTIMES) - The rain had begun to fall again on Sunday afternoon (Aug 27) when there was a roar over Interstate 610. A Texas Department of Public Safety helicopter was hovering overhead, a rescuer and a resident joined together by a harness and arms.

The men touched down in an emptied traffic lane. They unhooked from each other. Seconds later, the rescuer and his helicopter were off again.

And Robert Durbin, 33, was left to find his wife, Danielle, who had been airlifted in her pajamas minutes earlier. Shoeless, he ran through the parking lot that had sprung up on the interstate, searching, his eyes scanning the cars and vans. He soon found her in a television crew's vehicle.

They had been on the roof of their home since about 8 am, and they expected all of their possessions, except those in the attic, would be lost. "That was insane," Robert Durbin said of his family's ordeal.

The Durbins, whose first task after being reunited was to retrieve their daughters, who were at a relative's house, were hardly alone in being plucked to safety. Houston on Sunday was a study in desperate improvisation, streets and highways turned into rivers, boats and helicopters more useful than cars, and dramatic rescues taking place virtually everywhere one looked.

The National Guard and a flotilla of private boat operators swarmed Houston in search of residents in distress, many of whom had been frantically calling authorities for help all day long. Stranded residents mounted the backs of some soldiers, who waded through thigh-high waters to take evacuees to trucks that would drive them to safety.

During a break from Sunday's rain, the unflooded stretch of interstate near the Meyerland Plaza shopping center in south-west Houston became an impromptu staging area for emergency responders and volunteers offering up powerboats, kayaks and rafts.

On the highways, some motorists, stalled themselves, got out and tried to push others to safety. People searched their phones for traffic alerts and safe passages. Even National Guard soldiers travelling in civilian vehicles were left to consult Google Maps.

Once residents were rescued, whether by emergency officials or volunteers, they were typically unsure of where they would spend Sunday night and beyond.

National Guard soldiers used a Chevrolet van to ferry rescued passengers across still more flooded water to another dry area, where they would be relocated once again.

"They're going to take you from there to a shelter or something like that," Major Randy Stillinger of the Texas Army National Guard told some of his passengers. "I'm not sure, but it's better than being here." He added: "I wish I could do so much more for you."

During one ride, a woman asked if she would be safe in her eventual destination: "It's high enough that we're not going to drown?"

The rescues and searches played out all day.

Raoul Njobi earlier in the afternoon had shouted to the men launching a small motorised boat into a flooded out section of interstate. Begging for help, he explained that his sister was trapped in her car. He thought she was nearby, but her phone's battery had died.

"She's got a Ford Fiesta, white," Njobi said as the men tried to back their boat into the floodwaters.

"There's people stranded left and right," said the pilot of the boat where Njobi made his plea. "There's kids and pregnant women all over." Njobi, in what looked like a swimsuit, anxiously told his tale.

"I was talking to her, but now the communication doesn't work," he said. "Her phone is dead, and we aren't able to communicate." The last time the two spoke, Njobi said, the water had begun to come into his sister's car.

"I told her to stay on the top of the car and wait and wave so people can see her," he said. "Now we don't know what's going on exactly."

The men in the boat listened, then backed the boat off the trailer and into the water on what is ordinarily an exit lane for South Post Oak Road. Then they floated off in the direction Njobi pointed, as Njobi stood on a patch of dry land and watched.

At midday Sunday, nine National Guard vehicles were parked along the stretch of interstate. Soldiers in life jackets and camouflage pants were scrambling into a boat to make rescues in a nearby area, and they expected to be kept busy for hours.

Beatriz Abelenda sat in the front seat of a National Guard van, her poncho dry and the vehicle's emergency flashers clicking. Her home, close to Interstate 610, had not flooded. But she could not get to it.

"I was just trying to get home, and here we are," said Abelenda, whose son had managed to get to the house around lunch time and reported that it was still on dry land.

Abelenda, who has lived in Houston for her entire life, said that even in Harvey's early assault on Houston, she had never seen a storm so bad. Not Tropical Storm Alison in 2001. Not Hurricane Ike in 2008.

"I would say it's the worst," she said. "I'm worried. I'm worried it's just going to get worse. It doesn't look like it's going to get any better."