What you need to know about flooding, buying a new home
People who flood aren't always in a high-risk zone, experts say
HOUSTON – Houston has experienced several major floods since the beginning of the decade, and according to a Rice University/Texas A&M-Galveston study, many of those who flooded during these events were not in a high-risk flood zone.
Channel 2 Investigates spoke with experts on urban flooding, and environmental attorney and county leaders to find out what steps potential homeowners might be overlooking when considering flood risks -- and why these experts strongly suggest that everyone in the Houston area purchases flood insurance.
The Department of Public Safety estimates that more than 300,000 homes were damaged by Hurricane Harvey. You can view a breakdown of which counties sustained damage here.
Am I in a floodplain?
The Federal Emergency Management Agency, or FEMA, publishes floodplain maps, which show if an area is in a floodplain, and if so, the annual chances that a specific area will flood.
Typically, a 100-year floodplain indicates a 1 percent annual chance of flooding -- and a 500-year floodplain indicates an annual 0.2 percent chance of flooding.
You can check whether your home is in a floodplain here or by clicking or tapping here. The Harris County mapping tool also allows users to see where ponding during heavier-than-normal rains is a potential in a specific area.
However, Rice University professor Dr. Phil Bedient cautions that floodplain maps are only a good place to start.
And the executive director for the Harris County Flood Control District, Russ Poppe, said updating these maps is time-consuming and expensive.
Poppe said there are 22 watersheds in Harris County, and FEMA only provides the county with enough federal funding to map one watershed a year, and it can take as long as three years to map one watershed.
However, Poppe said, the district can decide to spend local dollars to map an area, but that typically only happens after an improvement project is complete.
If there is development in an area since the last update, flood risks can change before new maps come out. Poppe said the last time maps for every watershed in Harris County were updated was in 2007.
At the beginning of 2017, FEMA did release new flood maps for coastal portions of Harris County.
Poppe said the district is also updating maps for areas around Addicks Reservoir, Brays, White Oak and Sims Bayou.
Poppe said about 60 to 70 percent of the people who flooded during the Tax Day floods lived outside a 100-year floodplain.
Poppe added that Harris County has 2,500 miles of channels, but only about 1,300 miles are mapped. He said those areas that are mapped were done using FEMA-approved methodology developed after Tropical Storm Allison.
Poppe said if the other areas are mapped, different modeling approaches would have to be used and additional funding would be required.
“So, even if you’re not in a mapped area, it doesn’t necessarily mean you’re not at risk?” asked Channel 2 Investigator Robert Arnold.
“That’s right,” Poppe said.
Below are maps of Harris County’s watersheds and how the floodplain changed following Tropical Storm Allison.
Poppe said the plan going forward is to begin updating more floodplain maps after the completion of Atlas 14. The National Oceanic and Atmospheric Administration has been updating rainfall amounts and frequency across the United States.
Texas’ update is still pending. You can view an Atlas 14 map here.
What about different parts of town?
There are several historically flood-prone spots around our area. Bedient suggests looking at homes in the parts of town that did not flood during Hurricane Harvey. He said Rice is currently studying those areas to gain a better understanding of why certain spots fared better than others.
Rice professor and environmental attorney Jim Blackburn also suggested looking at which parts of town are higher than others and whether a particular home is at the bottom or top of a slope.
“Very, very slight changes in slope can make a big difference,” Blackburn said.
Bedient and Blackburn advised people to make sure they know whether a home is close to bayous, levees, rivers, creeks or other channels. Both said any of the above factors can affect whether water flows toward or away from an area.
Bedient offered another piece of advice.
“(You) want to be a good 18 inches or so above (the) center of (the) street,” he said. “Or 18 inches above curb -- one or the other.”
What about reservoirs and lakes?
Many residents did not flood specifically because torrents of rain were dropped on their neighborhoods.
“You're like, 'This is the most insane moment of my life,'" said Carolanne Norris, whose Kingwood home flooded. “The water was up past our chest.”
“You guys didn't flood specifically because it rained a lot over this neighborhood?” asked Arnold.
“No, we didn't even have standing water. That was what was crazy about it,” Norris said. "It never occurred to me that we would flood -- never, never."
Norris said the only time her home was potentially at risk of flooding was during the October 1994 floods.
“What floodplain are you in here?” asked Arnold.
“We're in the 500,” Chris Norris said.
The Norrises said their home didn't flood until after near-Niagara Falls amounts of water were released from Lake Conroe, which feeds, along with other watersheds, into the west fork of the San Jacinto River, which feeds into Lake Houston.
“The dam opened and we just kind of watched (the water go up),” Chris Norris said. “It was a couple of inches an hour coming up the street.”
KPRC heard similar stories from West Houston residents who watched their homes go under after water was released from the Barker and Addicks reservoirs into Buffalo Bayou. Thousands of homes behind these dams flooded when water stretched beyond the reservoirs. Hundreds of residents said they didn’t know their homes were at risk.
Both of these releases have prompted lawsuits from residents.
One of the Norrises' biggest complaints was that they never knew the San Jacinto River Authority was releasing that much water from Lake Conroe until after it happened.
“That was what was so hard about this, the ability to prepare was taken away from us,” Carolanne Norris said.
What is being done about flooding going forward?
Poppe said the district is focusing on four main projects to reduce flooding risks for about 20,000 residents. Those projects involve Clear Creek, Hunting, Brays and White Oak bayous. Poppe said these projects combined will cost between $550 and $600 million to complete. Each year the district has $60 million to work on these projects, he added.
Poppe said while federal funding is not a guarantee each year, over the past five years, the district has received an average of an additional $20 million.
Poppe said the district also has submitted $70 million in reimbursement to the federal government for work done on these projects.
Blackburn also believes home buyouts will be necessary to truly reduce risks in many flood-prone areas.
Since 1985, the district has bought out more than 3,000 homes and properties that were considered at the greatest risk of continued flooding.
District officials said they have identified an additional 3,000 homes that may meet the requirements for a buyout, and since Harvey, 3,345 people have expressed initial interest in having their home bought out.
However, buyouts are subject to federal requirements, and largely, to federal funding.
Currently, the county has authorized $20 million to be spent on home buyouts and authorized a $17 million annual grant application to FEMA for pre-Harvey home buyouts.
If FEMA approves the application, the county could buy out 100 homes that were identified as meeting the criteria prior to Harvey. Mayor Sylvester Turner said he is working with FEMA on possible buyouts in the city.
Harris County Judge Ed Emmett also released his proposals for reducing flooding in our area, which you can read more about here.
Copyright 2017 by KPRC Click2Houston - All rights reserved.