FLOOD CONTROL: Water from 2 reservoirs will swell Buffalo Bayou; state crews build temporary dam on I-10
Releases from the Addicks and Barker dams sent floodwaters into an already swollen Buffalo Bayou, which was flooding thousands of Harris County homes Wednesday as officials rushed to relieve pressure on the 70-yearold reservoirs intended to protect the sprawling city downstream.
Meanwhile, crews with the Texas Department of Transportation were busy installing a mile-long temporary dam along the westbound lanes of Interstate 10 near Texas 6 in the hopes of having the lanes open by Wednesday evening. Without the barrier, TxDOT spokesman Danny Perez said officials feared they could lose the entire roadway to surging waters released from the aging reservoirs.
By early Wednesday, more than 4,000 homes near the reservoirs had flooded, mostly from water that backed up upstream. But with water spilling out from Addicks dam, U.S. Army Corps of Engineers increased the release of waters from both reservoirs so they could capture ad-
ditional rain in the coming days.
“We have to get this water out as soon as possible,” Edmond Russo with the U.S. Army Corps of Engineers. “These dams have to be cleared before the next storm.”
Several thousand homes below the dams already had taken on water since the storm began, from both the releases and other swollen waterways. Some of those homes were expected to flood a second time, while others that initially had escaped Hurricane Harvey’s wrath were inundated from the releases.
In spite of the new flooding, county flood control and Army Corps officials said the labyrinth of channels, detention ponds and dams constructed over decades to take water from the Houston region’s perennial rainfall out of its sprawling neighborhoods and drain it into Galveston Bay largely performed as designed during Harvey’s record-shattering deluge.
But performing as designed was not enough to keep the region from devastation.
Nor was it any consolation for homeowners who flooded for the first time.
“Apparently, they decided to release from the dams, and that’s why the water is so high,” said Anibal Dam, an engineer who owns a Houston home remodeling business.
He and his three children had to be rescued from their threestory townhome at the Village on Memorial as the water rose Tuesday.
“I mean, I don’t think this level (of flooding) is only because of the rain because it started to increase significantly today,” he said.
Flood control officials said that it would be near impossible to develop a system that could protect everyone in the county from a storm like Harvey.
“The volume of water that fell during this time period is not a volume of water that we can design for,” said Matt Zeve, the Harris County Flood Control District’s director of operations. “Fifty inches of rain, over the course of two to three days, is not something that our systems are designed to handle.”
The problem, experts say, is Houston’s relentless growth, much of which occurred during a time when flood control standards were obsolete, increasingly has placed home and subdivisions around the area’s ubiquitous waterways.
Bayous that had been widened, deepened, straightened and lined with concrete to whisk floodwaters out quickly topped their banks. Water pooled behind the Addicks and Barker dams — constructed some seven decades ago on the prairie northwest of Houston to hold back storm water draining out east and south into the Gulf — into thousands of homes and flowed out of emergency spillways into surrounding neighborhoods.
The Houston region’s flood control infrastructure, for the third time in three years, buckled under a storm that should have only a .2 percent chance of happening every year, inundating almost a third of Harris County, flooding thousands of homes and killing more than 30 people.
For some, the devastation in an already flood-weary region clearly showed a need for a different approach to infrastructure planning.
“The systems were vastly overwhelmed,” said Phil Bedient, a Rice University engineering professor who has studied flood planning and control. “These systems are legacy flooding problems across the county. I do believe it’s time for a sea change and major policy change in the way we do things.” Inadequate standards
Flood control in Houston is as old as the city itself, with farmers in the 1800s building drainage channels to push water out of their crops. After 16 “major floods” from 1836 to 1936, local officials began in earnest to tackle larger flood control projects, like the Addicks and Barker dams.
Over the decades, bayous were deepened, widened and straightened so they could channel floodwaters out of populated areas quickly. Some were lined with concrete to make water flow out even faster.
The understanding of climate and flooding, however, was inadequate. In the late 1940s, infrastructure was designed to handle only a two-year storm. In the 1960s, that standard grew to a 25year storm.
It was not until the 1970s that the National Flood Insurance Program came into being and the first floodplains began to be mapped in Harris County — after nearly 2 million people already lived here.
In the aftermath of Tropical Storm Allison, the county and city engaged in a massive study of the county’s floodplains and rainfall. It found that in some cases, floodplain maps were off significantly. It also found that some estimates of what a 100-year event is — rainfall that has a 1-percent probability of occurring in any given year — were off by several inches.
Nearly every flood control project, and every detention pond built by developers to offset for paving over permeable land, is built to the 100-year storm standard. If the standard is off, so is the infrastructure designed to compensate for such events.
Some experts and climate scientists say that estimates today again could be off, as the increasing number of severe storms suggest that climate change is having is having an effect.
The flood control district has contributed $200,000 to a federal study to address that question.
The county routinely attempts projects to retrofit outdated infrastructure. For example, a 25-year, $400 million project to widen and deepen parts of Sims Bayou removed some 4,400 homes and businesses from the 100-year floodplain.
Zeve said the county has estimated providing protection for a 100-year storm for everybody in Harris County would cost more than $25 billion.
Harvey, however, was at least a 500-year storm.As were the last year’s Tax Day and Memorial Day floods.
“To handle a storm like what we had and not have flooding, we’re talking, I would just throw out an astronomical number like $100 billion dollars,” Zeve said.
Mayor Sylvester Turner on Wednesday called for a reinvestment in flood control infrastructure in Harvey’s aftermath.
“We need to spend much, much more on infrastructure,” Turner said. “We’ve been very stingy on infrastructure. We need more financial support on mitigating flooding.”
Bedient said the region needs to reinvest in green space to stem the spread of impervious pavement and needs to increase the number of buyouts of homes in flood-prone areas. He also suggested the county explore using pumps to put the water underground.
“I think it’s time to get outside the box,” Bedient said.
The flood control district has altered some of its approach in recent years. It explored more largescale projects in the northwest parts of the county — building massive channels and detention basins near Cypress Creek and Upper Langham Creek.
It also is exploring the idea of removing parts of White Oak Bayou’s concrete lining and whether floodwaters can be stored in aquifers underground. ‘The hardest test’
The largest features of Harris County’s flood control infrastructure are the Addicks and Barker dams, constructed some seven decades ago to hold back storm water from the booming city downstream.
Today, they hold back tens of billions of gallons of water when it rains to protect downtown, the Texas Medical Center and more than a million residents below.
In Harvey, the dams faced their fiercest challenge.
“This is the hardest test they and we have ever faced,” said Russo, deputy district engineer for programs and project management for the U.S. Army Corps of Engineers.
The reservoirs filled to their highest levels ever, and officials were forced to release water into an eroding, flooding Buffalo Bayou below. The staggering volume of water triggered the opening of floodways used only if the dams are in danger of spilling over. Upstream, thousands of homes built in recent years as the city sprawled outward took on several feet of water that continued Wednesday.
Below the dams, Duncan and Alison-Shanklin, who live two blocks from Buffalo Bayou in the Memorial area, stood on the bank and gauged the bayou’s rise by the yellow “high water” sign sticking out of the swirling water.
They do not question the need to relieve pressure on the Barker and Addicks reservoirs.
“They still have to release water, even if we suffer the consequences, for the integrity of the dam,” said Duncan Shanklin. “It’s an old dam, and they’ve got to do that because if there’s a breach in the dam, everybody is in trouble.”
The dams themselves are beat up.
In 2007, the Corps found many aspects of the 70-year-old dams — including the embankments, conduits and water control structures — “probably inadequate” for an extreme storm. Two years later, the structures got the Corps’ worst safety classification.
Since then, the Corps has embarked on a $73 million retrofitting project to make sure the dams are safe. That project is expected to be completed by 2021, and Corps officials said Harvey’s inundation has not affected the timeline.
They also said Harvey had not damaged the dams any further and did not anticipate needing to conduct any repairs.
For its part, Harris County Flood Control District this week began studying the damage inflicted by Harvey on its own infrastructure.
Some rain gauges — used to measure rainfall — were washed away during the storm.
After the Tax Day Flood, flood control officials estimated $65 million in damage, including eroded waterways, cracked concrete lining and damaged culverts.
“I expect more damage than Tax Day, because there’s more water,” Zeve said.
“The systems were vastly overwhelmed. These systems are legacy flooding problems across the county. I do believe it’s time for a sea change.” Phil Bedient, Rice professor