Texas flooding to force 30,000 into shelters

More flooding is expected to force up to 30,000 people in Texas into shelters, emergency agencies say.

Tropical storm Harvey is set to dump more rain on Houston on Monday, with forecasters warning the flooding will peak on Wednesday and Thursday.

To make matters worse, the US Army Corps, which has been helping the relief effort, says it will be forced to release water from two reservoirs near the city into a bayou running through Houston.

"If we don't release now, the volume of uncontrolled water around the dams will be higher and have a greater impact on the surrounding communities," said Colonel Lars Zetterstrom.

The head of the US Federal Emergency Management Agency (FEMA), Brock Long, has described the worst flooding in Texas in 50 years as a "landmark event".

He added 450,000 people are expected to seek disaster recovery aid.

Man rescued from submerged car in Houston floods

Homeland security secretary Elaine Duke also warned of "life-threatening flooding" and cautioned: "We are not out of the woods yet, not by a long shot."

Up to 20 more inches of rain could fall in the coming days, on top of the 30 inches some areas have experienced so far.

Thousands flee Texas flooding

Storm Harvey has devastated parts of Texas, including Houston - the fourth biggest city in the US - since it came ashore on Friday as a Category 4 hurricane.

(SKYNEWS)