Heavy rains drenched southeastern Texas on Monday, causing flash floods and damage across the US state, prompting a state of emergency to be declared in nine counties.
Residents have been evacuated, some are left without power and schools and universities have closed with some roads collapsing.
A flash flood watch will remain in effect until Wednesday for most of the region, catastrophe modelling firm AIR Worldwide reported.
“Rainfall that began on Sunday night continued through Monday, producing 10–20 inches of rain in parts of southeastern Texas, reaching rates as high as 4 inches an hour,” said Daniel Rees, senior analyst at AIR Worldwide.
“A series of thunderstorms doused the (Houston) suburbs with almost 18 inches of rain on Sunday night―the same amount of rainfall expected for this area in the five-month span of January 1 to May 30―and delivered 6–8 inches of rain to central Houston on Monday.
“An official from the Harris County Flood Control District said that 240 billion gallons of rainwater had fallen in the locality from Sunday to Monday. A new daily maximum rainfall record was set at the Houston Intercontinental Airport on Monday with a total of 9.92 inches recorded, breaking the previous record of 8.16 inches from 1976,” said Rees.
The National Weather Service (NWS) issued a flash flood emergency for the hardest-hit Houston Metro area and flash flood watches for Austin, San Antonio, Dallas, Fort Worth, Tyler-Longview and Texarkana, and reported more than 110 subdivisions have reported flooding.
Several rivers were at major flood stage in five areas on Monday, according to the NWS.
This includes the Little River near Rockdale, White Oak Bayou at Houston, Peach Creek near Splendora, the West Fork of the San Jacinto River near Humble, and Cypress Creek near Hockley and Westfield, where some Harris County residents were forced from their homes on Tuesday morning due to high water levels.
Cypress Creek at Cypress crested at 127.5 feet just below the 1994 record of 127.6 feet.
“Buffalo Bayou and the White Oak Bayou flowing through the downtown Houston area crested at 31.7 feet and 36.9 feet, respectively, significantly below their 1935 historic flood levels of 49.0 feet and 51.5 feet,” said Rees.
“Harris County Flood Control District reported 13 bayous and creeks had breached their banks, including Brays Bayou, which has caused repeated flooding of adjacent structures within the past 10 years,” he added.
The Governor of Texas declared a state of emergency in nine counties on Monday afternoon due to flooding conditions.
Forecasts alerting residents to the upcoming rains and the chance of flooding were issued as early as Friday, and flash flood warnings have been issued throughout.
Although rainfall has ended, flood warnings for Colorado, Washington, Harris, Liberty, Walker, San Jacinto, Waller, Grimes, Montgomery, Austin, and Fort Bend Counties in southeastern Texas were in effect through midday Tuesday.
Evacuations are underway throughout southeastern Texas after more than 1,000 homes were partially submerged in Harris County alone, which includes the neighborhoods of Braeswood Place, Rosslyn Road, and Cypresswood.
About 123,000 residents were
Some roadways collapsed while others were inundated, with local fire departments warning that
Two dams along Interstate 10 and Texas 6 on Houston’s west side have been deemed “extremely high risk” by officials and are currently under investigation; expected to reach 50% capacity by mid-Tuesday.
Houston County officials reported more than 1,200 water rescues by early Monday afternoon.
Public schools and universities were forced to close. More than 500 flights scheduled for departure from Houston’s two major airports were cancelled. Bus and rail services were also suspended.
The National Oceanic and Atmospheric Administration and the University of Oklahoma are reportedly calling the flood a 1-in-200 year event.
Flood damage and associated losses can result from time-related elements (such as length of exposure to flood water, how quickly mitigation is undertaken, and extent of business interruption), and can vary greatly by exposures.
Therefore, the impacts to the insurance industry will become clearer as flood waters recede and assessments can be conducted, said AIR Worldwide.
Rees added: “Additional heavy rain is expected in the Houston Metro area through at least Wednesday that will also reach parts of Oklahoma, Kansas, and Louisiana.
“This could worsen conditions in areas already hardest hit by flooding, and cause new incidents of flash flooding in other locations,” he said.