TV reporter rescues man from floodwaters as Hurricane Harvey lashes Texas

A US TV reporter and photographer have helped rescue a truck driver trapped in floodwaters in north Houston as the city was lashed by former Hurricane Harvey.

Captured on the broadcast, KHOU 11 reporter Brandi Smith can be seen on a bridge above the stricken truck.

The reporter then flags down a passing sheriff towing a boat to alert them to the truck driver.

A zoomed in shot shows the water rising in the truck's cabin.

The reporter yells out to the man trapped in the truck to alert him to the boat.

The video continues with updates on the rising flood water as the sheriff shifts the boat into the flood waters.

"I cannot imagine how terrifying it would be to be stuck right there right now," Smith tells the camera.

The sheriff motors the boat down to the man and help him clamber out the window.

Smith and the truck driver share a hug after his rescue.

Emergency crews have already rescued more than 1,000 people around Houston as the storm pounded the region.

Harvey came ashore late on Friday as the most powerful hurricane to hit Texas in more than 50 years and has killed at least two people.

Harvey has caused chest-deep flooding on some streets in Houston as rivers and channels overflow their banks.

Flood damage in Texas from the storm could equal that from 2005's Hurricane Katrina, an insurance research group has said.

Insurance Information Institute said on Sunday it was still too soon to estimate the damage to homes and businesses.

"It could be a flood loss like Katrina because of the amount of water that's coming in ... not as much wind as it will be water," institute spokeswoman Loretta Worters said.

Hurricane Katrina resulted in more than $US15 billion in flood insurance losses in Louisiana and Mississippi that were paid by the National Flood Insurance Program (NFIP), a federal program that is the only source of flood insurance for most Americans.