Harvey May Exceed 500-Year Flood Levels in Houston

The intersection at Heights Boulevard and I-10 frontage road.
The intersection at Heights Boulevard and I-10 frontage road. Photo by Meagan Flynn
Unrelenting, Tropical Storm Harvey has now inundated Houston with more than two feet of rain, with three to six inches soaking the already saturated or submerged ground overnight as rescues and evacuations have continued in dangerous conditions.

Overall, more than 9 trillion gallons of water have fallen on the region since Harvey began. It has been called a 500-year flood — and in fact, the U.S. Army Corps of Engineers said while discussing the Addicks and Barker reservoirs that "this event has the potential to exceed a 1,000-year flood plain threshold." According to the National Weather Service, the storm exceeded the floods caused by Tropical Storm Allison in half the time.

The vast majority of bayous are still over their banks, with many breaking or shattering records, such as Cypress Creek at I-45: 11 feet over its banks. Many in western Harris County are only expected to swell — particularly the Buffalo Bayou — as the U.S. Army Corps of Engineers releases some water from the Addicks and Barker reservoirs to relieve some pressure on the dams, now holding more water than they ever have before. They were built in the 1940s. More homes in that area are also expected to flood; all roads in that area will be flooded and closed, said Edmond Russo of the Army Corps of Engineers.

"They have to protect the integrity of the dams, because they were built to protect Houston," said Harris County Judge Ed Emmett at an early morning press conference. "But we also have to balance that with protecting the people who live on both sides of the dams. It's not an easy situation."

Mandatory and voluntary evacuations overnight commenced throughout areas in Fort Bend County as a result of risks posed by the controlled Addicks and Barker reservoir releases and the rising Brazos River. (See a map of all voluntary and mandatory evacs here.) And in Conroe, evacuation orders were also issued in a dozen communities because of record-level controlled releases from Lake Conroe, now roughly 205 feet above sea level.

Forecasters say that, after last night's deluge, the worst of the rainfall has largely passed, but will still continue throughout the day and the week, not helping the area's already-catastrophic flooding. More than 15 inches is still expected through Wednesday, possibly up to 25 inches.

The City of Houston Office of Emergency Management did not have updated numbers on overnight rescues as of 7:45 a.m., but Mayor Sylvester Turner is expected to provide an update at a 9:30 press conference.

After receiving "an overwhelming number of inquiries" from people and corporations who want to help Houston, Mayor Turner announced that he has created a Hurricane Harvey Relief Fund for donations, administered by the Greater Houston Community Foundation.

“We are getting calls from across the country and right here in our hometown, and the generosity of people who understand this disaster is truly amazing,” Turner said. “Together we can make a difference to those who will need extensive help to get back on their feet once this storm is over.”

Those who want to donate to help with rebuilding and provide relief to the hundreds of people since evacuated to various shelters, including the George R. Brown Convention Center, can go here.

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Meagan Flynn is a staff writer at the Houston Press who, despite covering criminal justice and other political squabbles in Harris County, drinks only one small cup of coffee per day.
Contact: Meagan Flynn