Houston floods: Hurricane Harvey rain is heaviest in history
- "Catastrophic" flooding in the US state of Texas is only expected to worsen in coming days as waters rise following a storm of historic proportions.
A record 30in of rain (75cm) has already fallen on the city of Houston in the wake of Hurricane Harvey, turning roads into rivers.
The rainfall in Texas set a new record for the continental US, the National Weather Service said on Tuesday. A rain gauge in Cedar Bayou recorded 51.88 inches (132 cm) of rain since Friday.
The city of Houston has declared a night-time curfew as it battles the impact of Hurricane Harvey.
The curfew will run from 00:00-05:00 local time (05:00-10:00 GMT) for an indefinite period. Relief volunteers, first responders, and those going to and from work are exempt.
Mr Trump has already declared a federal state of emergency in both Texas and nearby Louisiana, where Harvey is expected to make landfall again on Wednesday morning.
Harvey made landfall as a category-four hurricane late on Friday, bringing flooding described by officials as unprecedented. It was later downgraded to a tropical storm.
More than 3,000 people have been rescued in and around Houston, the fourth-largest city in the US, where about 6.6m people live in the metropolitan area. Helicopters have plucked victims from rooftops.
At least nine people are reported to have died in incidents related to the storm, Texan officials say.
Governor Greg Abbott has activated the entire Texas National Guard - some 12,000 so-called "civilian soldiers" - to assist national forces in search and rescue operations.
The area is expected to have received a year's rainfall within a week.
Meanwhile, army engineers have begun releasing water from two dams controlling water flowing along a major river into the heart of Houston.
Officials said they were opening the Addicks and Barker dams to stop water spilling into neighbouring communities, but that this could cause further damage down the Buffalo Bayou.
- source : BBC