By Jon Herskovitz

AUSTIN, Texas (Reuters) – A new round of storms dumped more rain on flood-hit parts of Texas on Thursday, threatening to aggravate already swollen rivers, deluge homes and force more evacuations.

The National Weather Service (NWS) issued a flash flood warning for parts of central Texas on Thursday morning and placed most of the state on a flash flood watch due to a slow-moving storm system expected to linger through the weekend.

Texas Governor Greg Abbott is expected to tour flood-hit areas on Thursday. He declared a state of disaster in 31 Texas counties on Wednesday, mobilizing state resources to help manage the disaster.

“The state of Texas stands ready to assist all counties affected by severe weather and has dedicated the resources necessary to ensure the safety of those at risk,” Abbott said.

Six people were killed in the past week in Texas due to severe weather.

Thousands of people have evacuated their homes in low-lying areas, rivers have swelled to levels not seen in more than 100 years and emergency workers have completed hundreds of high-water rescues.

Evacuations were ordered for parts of two towns in Fort Bend County, about 30 miles (50 kms) southwest of Houston, where the Brazos River has risen to levels not seen for more than a century.

“It hasn’t been this high since 1913,” said Major Chad Norvell with the Fort Bend County Sheriff’s Office. “Nobody really had an idea of what it would do. It is filling areas where we didn’t expect, and some that we did.”

As much as 10 inches (25 cm) of rain could fall in the Houston area in the coming days, the NWS said, just weeks after eight people were killed in floods that hit the metro area.

This could touch off another round of flooding in the fourth most populous U.S. city, it added.

(Additional reporting by Jim Forsyth in San Antonio; Editing by Jeffrey Benkoe)