reduce flood risk

What Can Be Done to Reduce Flood Risk?

Flood-control experts have many tools in their tool chests to reduce flood risk. They include:

  • Widening channels to increase stormwater conveyance
  • Deepening channels to increase stormwater conveyance via dredging
  • Benching, i.e., reducing floodplain height to increase stormwater storage
  • Building retention and detention basins to create more storage and reduce flood peaks
  • Improving building codes to mandate higher home elevations
  • Requiring greater setbacks from rivers, streams and bayous
  • De-snagging to prevent log-jams from backing water up
  • Preserving wetlands, grasslands and forests to absorb and slow runoff, and to create recreational opportunities for nearby homeowners
  • Bio-swales and ditches to create more stormwater storage and positive drainage around homes
  • Buying out flood-prone homes and converting the property to recreational or flood-mitigation space.

I’m sure more techniques exist. But those represent the big categories.

Complex Decisions Involving Many Factors

No one tool works for all situations. And many of the tools that reduce flood risk fly in the face of other human values. They may conflict with other values beyond safety, that we hold dear. Consider, for instance, property rights, individual freedom, job formation, expanding the tax base, a desire to live near water, and risk-taking.

So how do professionals decide which tools to apply where and when?

Again, it depends on a number of factors. To name a few:

  • What are the benefits compared to the costs?
  • Does the cost of the cure exceed the cost of the damage?
  • What is the recurrence interval of flooding in a certain area?
  • Are you trying to fix a problem or prevent one?
  • Is the trouble spot pre- or post development?
  • How frequent and deep will likely flooding be?
  • Are changing conditions upstream contributing to increased flood heights?
  • How much damage will flooding cause?
  • Is State or Federal disaster-mitigation aid available?
  • Is Disaster Relief aid available?

Homeowner Inquiry Prompted Exploration

A homeowner reacted to one of my posts today. She lives in a low-lying area near FM1485 and the San Jacinto East Fork. It flooded badly on May2, 2024. She was certain that dredging and tree removal from the East Fork would help. But after investigating the area online, then from the ground and air, I wasn’t sure.

The normal river elevation in that area is 47.25 feet.

But on May 2, the river rose to 77.4 feet – 17 feet above the top of the river banks and 30 feet above normal!

Jeff Lindner, Harris County Meteorologist, had this to say about the May flood. “Since 1994, this was the second highest crest of the river at FM 1485. It exceeded Tropical Storm Imelda by 4.0 ft and the October 1994 flood by 1.0 ft.”

Lindner continued, “The flood of record remains Harvey which was 4.0 ft higher than the May 2024 event. The river exceeded the .2% (500-yr) exceedance probability elevation at the FM 1485 bridge by 1.5 ft. The table below shows the top five highest peaks on the East Fork of the San Jacinto River since 1994 at that location.”  

Date Peak Elevation 
  • 8/27/17 (Harvey)            81.2 
  • 5/2/24                              77.4 
  • 10/18/94                          76.2 
  • 9/19/19 (Imelda)            72.8 
  • 11/14/1998                      71.6 

HCFCD calculates the elevation of a 100-year flood is 70.6 feet.

So…

Residents in this neighborhood experienced five 100-year-or-greater floods in 20 years. That’s one every four years. Is the risk 1% or 25% per year?

See the FEMA floodplain map below for the area in question.

It shows you how difficult flood prediction can be. It also shows you why even nature lovers should give water in Texas a wide berth unless they are prepared to lose everything. The May flood wasn’t even related to a tropical event!

u
Yellow/green diagonal line is the Harris/Montgomery County line. Image shows neighborhood S of FM1485 near East Fork. Crosshatch=floodway, Aqua=100-year and Tan=500 year floodplain.

Unfortunately, most of the homes in this neighborhood didn’t look like people could afford to lose everything. And I saw several that had been totally obliterated along with two roads that washed out.

I’m not sure what this was. But it was the only structure semi-standing for blocks around.

Professionals Say Buyouts Best Option In This Case, But…

In an area like this, flood-mitigation professionals have few good options. Given the depth of flooding, three professionals told me that intervention would have to be on a massive and costly scale to make a difference. As a result, each suggested buyouts as the best, most cost-effective alternative in this area.

Shortly after the May event, I interviewed a young couple named Daniel and Kathleen Moore. They lived on some of the highest land in the subdivision, but had flooded three times in the seven years that they owned their home (Harvey, Imelda, and May 2024).

They were hoping for a buyout. I called again today to see if they succeeded, but they were selling their property and moving out of state with their new baby. Why?

While Daniel was restoring the home, someone burned it to the ground on July 28th. Nothing stands there now but a charred chimney.

This was a heartbreaking story that deeply affected me personally. I once lived in a home near a creek that flooded frequently when I had two young babies.

While buyouts may sometimes be the most cost-effective option, they are not easy, according to a County Emergency Management Director that I interviewed. Counties must apply for FEMA buyout money and then it can take years to evaluate and rank all the applications and distribute the money.

Forest Cove buyouts took five years after Harvey to complete.

Ironically, the fact that the Moore’s were in a 500-year floodplain may have hurt their buyout chances. FEMA likes money to go to homes that are insured but which flood frequently.

So What About Dredging and Tree Removal?

The Moore’s lived in Montgomery County. But the other family that contacted me lived on the Harris side of the county line in the same neighborhood.

Typical scene in East Fork south of FM1485
Area has trees down everywhere.

Experts I talked to suggested dredging wouldn’t make an appreciable difference given the narrow width of the river channel and the height of flooding. Plus, it could undermine more trees along the heavily wooded banks.

Removing trees that have already fallen, they say, is a good idea. They could float downstream, form log dams that flood other homes, and/or harm boaters in Lake Houston. But who is responsible for removing them?

I asked Matt Barrett, head of SJRA’s Flood Management Division. Said Barrett, “SJRA’s jurisdiction does not include Harris County, so projects constructed in Harris County would have to be led by HCFCD.”

Distant Chances for Other Flood Mitigation

That said, Barrett also volunteered that SJRA has partnerships with both HCFCD and the City of Houston. The entities work together on multiple projects from the San Jacinto River Basin Master Drainage Plan. But finding funding remains a challenge. And large scale projects are not quick to implement.

That brings us full circle to the original question in the headline. What was or is the best thing(s) homeowners can do to reduce their flooding chances? In my opinion:

I’m not a professional engineer and I do not render professional engineering opinions. But I have interviewed a lot of flood victims who wish they could turn back the hands of time and build on higher ground.

Foundation being endangered by riverbank erosion.

If you have the slightest qualms about flooding when purchasing property, make sure you consult a professional engineer to evaluate your risk and mitigation options.

Posted by Bob Rehak on 8/20/24

2548 Days since Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

Randy Reagan home

One Man’s Struggle Against Rising Floodwaters, Sand Mines and SJRA

8/10/2024 – Sometimes Randy Reagan must feel that he has struggled for most of his adult life against rising floodwaters, sand mines and the San Jacinto River Authority (SJRA). He has flooded six times in the last nine years. Still, he’s rebuilding on a lot he bought 30 years ago. But he’s doing it differently this time.

May 2024 Flood. Reagan property in background. Note roof of submerged vehicle in foreground.

Erosion of Country Lifestyle

Reagan grew up not far from the San Jacinto West Fork. He remembers a time as a child before Lake Conroe when the river ran clear and teemed with fish.

His wife grew up in the same neighborhood. Her parents were the first settlers in an area that came to be known as Bennett Estates between FM1314 and the San Jacinto West Fork.

They loved living near the river and all the abundant wildlife. So Reagan bought 5.5 acres for $10,000 back in the mid-’90s. He put a mobile home on it and started raising a family. He hunted all the meat his family ate from his own property and the surrounding forests. Life was good.

The 1994 flood was the highest ever in that area. The SJRA released 56,000 cubic feet per second (CFS) from Lake Conroe during the storm. So Reagan elevated his home a foot above the high water mark from that storm and figured he was safe.

But gradually, his dream of peaceful, country living turned sour. In the mid-2000s, two companies started mining sand near his home – one a few blocks north, the other immediately south of his property.

The mines accelerated runoff and erosion. They also changed local drainage patterns in ways that flooded his property.

In the meantime, upstream areas grew, also increasing runoff. And by the time I first met Reagan in early 2020, his property had flooded five times in four years. The worst: Harvey in 2017. Ninety-three inches of water invaded his home. That’s almost 8 feet! See that story here.

Eventually, Reagan tore down the mobil home. Repeat flooding had caused the foundation to shift and destabilized it. He and his wife began living in his workshop or with relatives.

Reagan tried to get a low-interest SBA loan through FEMA to rebuild. But they denied him because he had “let his flood insurance lapse after Harvey.”

“Of course I let it lapse,” said Reagan. “There was nothing left to insure. The home was gone.”

Fast Forward Four Years

The May flood this year swamped his property again after the SJRA opened the gates on Lake Conroe and began releasing 72,000 CFS, the second highest release rate in SJRA history.

Reagan points to high water mark on his shop from May 2024 flood – 52 inches.

Only Harvey exceeded that rate. SJRA released 79,000 CFS in 2017 during Harvey.

Since then, Reagan began planning his comeback against Mother Nature, the sand mines and SJRA.

His dream now is to build a foundation for a new home up 10 feet above the original level of the land. That would make the land higher than the Harvey high-water mark.

Then he wants to build a new home up on stilts, another ten feet above the elevated foundation. It would be elevated 20 feet above his first home on the property and more than 10 feet above Harvey. Hopefully, that will keep him safe for a few years.

The retired oil-field worker and bull rider is looking at designs from UB Homes. He also hired a MoCo excavation company, Graham Land Services, to excavate a pond at the back of the property.

Dirt from pond excavation (background) is being used to build up home pad (foreground).

Dirt from the pond is building up the foundation where his new home will go.

Pros and Cons of Rebuilding in Location that Floods

On the plus side:

  • Mining behind his property has ceased. He now has a 42-acre pond behind him. No one will ever build behind him and spoil his view.
  • He can still hunt on his property.
  • Despite the flooding, property values have appreciated. Not far away, a home recently went up for sale at $1.4 million.
  • Development in surrounding areas has brought shopping, services and hospitals closer to home without changing his country-living atmosphere.
  • The May flood deposited fish in Reagan’s pond, which are now thriving.
Randy Reagan property lower right.

On the minus side:

  • All the tractor work has taken a toll on Reagan’s aging body. He complains of aching joints and bulging disks in his back and neck. He’s also fighting knee and shoulder pain from a lifetime of backbreaking work in the oil fields and on his property.
  • He wishes SJRA would pre-release water from Lake Conroe at much slower rates in advance of major storms, but has little hope that they will. “This May flood could have been totally avoided if they would have let water out sooner,” said Reagan. “SJRA needs to start operating the Lake Conroe Dam a lot better than what they’re doing.”
  • Reagan feels SJRA places Lake Conroe recreation above the protection of downstream property.
  • He feels he would have to move north of Huntsville to find the kind of flood-safe country living he once enjoyed. “It’s hard to get a piece of country living anymore in Montgomery County. It’s all going away,” said Reagan.

A Pioneer Spirit

Reagan typifies the struggle many Houstonians feel. He loves nature and living near water – until floods exact their terrible price. Still, he returns. To fight for a life he loves.

Reagan takes a break from moving in front of the property being raised for a new home.

I admire the fact that he’s not waiting for others to protect him from the ravages of West Fork flooding. By elevating his property and home, he’s protecting himself and his family.

Posted by Bob Rehak on 8/10/24

2538 Days since Hurricane Harvey

HCFCD Releases Final Report on Hurricane Beryl

8/5/24 – Harris County Flood Control District (HCFCD) has released its final report on Hurricane Beryl. The amazingly detailed, fact-filled, 30-page report by Jeff Lindner, Harris County’s meteorologist, covers the storm’s origins, rainfall, storm surge, high-water marks, wind speeds, flooding, and more for locations throughout the County.

Every sentence contains nuggets of information that you can use to amaze your friends, relatives in other states, and insurance agents.

Wind Speeds Up to 99 MPH

I’m not joking about insurance agents. One homeowner told me an adjuster denied her claim based on the fact that the wind was “only 37 MPH.” This report shows both average wind speeds and gusts. According to the official report, peak gusts in the Lake Houston Area were 69 MPH – almost double what the adjuster said.

Kyle Field at Texas A&M recorded the highest gust – 99 MPH.

Highest Storm Surge since Ike

Have a home near the shore? You may be interested to know that Beryl produced the highest storm surge since Hurricane Ike in 2008.

Storm surge averaged 5-7 feet above ground level along the coast, near the west side of Galveston Bay, Clear Lake, and the lower San Jacinto.

Water levels at the ship-channel turning basin reached 9 feet above ground level.

The high surge levels are likely the result of freshwater descending in watersheds as wind drove seawater into the upper portions of the ship channel.

Rainfall Intensity

Rainfall intensity was very high in places at times.

The Houston Transtar Center in the Buffalo Bayou watershed received 9.9 inches in 6 hours. There’s only a 2% annual chance of that (meaning it was a 50-year rainfall at that location). Transtar also received the highest 24-hour total – 12 inches (a 4% annual chance or 25-year total).

Out of 193 gages, 82 (42%) recorded an inch of rainfall in 15 minutes.

Rainfall Totals

Rainfall totals were less impressive due largely to the speed of the storm.

Most of the county received 24-hour totals of 6-9 inches. Higher totals generally fell south of I-10.

Six-hour rainfall amounts averaged 4-7 inches across most of the county.

Rainfall rates on the Atlas 14 chart for both 6- and 12-hour periods generally fell between 2- and 10-year events.

24-Hour Rainfall Totals during Beryl. HCFCD report also contains totals from shorter time periods.

The report noted that storms before Beryl had left the ground highly saturated. That increased runoff.

Only 10 Homes in County Flooded

Channel flooding was moderate. Approximately 10 structures flooded throughout the county. All suffered flooding in the past. They were built in areas with very low elevations.

Forty out of 193 gages reached or exceeded “flooding-likely” levels. That means the channels were full to the top of their banks.

Had the storm moved slower, Beryl could have been a very different story!

Other Damage

Power outages that resulted from high winds blowing trees into power lines created by far the largest impact to infrastructure.

2.26 million homes lost power – some for up to 11 days. The Lake Houston Area was among the hardest hit because of the dense forests here. The density adds a degree of difficult for both maintenance and repair crews.

Note uprooted tree to left of bend in trail still leaning over power lines in Kings Forest. Photo taken 8/4/24.

Twenty-eight days after the storm, dead trees and limbs still clog streets and lean on power lines.

Intense rainfall occasionally caused flooding of streets and roadways. Portions of SH288, I-10 and I-45 flooded and became impassable at times.

Beaches eroded along most of the upper Texas Coast. High tides and storm surge overtopped and destroyed entire dune systems.

Beryl also damaged coastal roadways, beach access walkways, and private as well as public properties.

High-Water Marks

A table on page 30 compares the high-water marks at dozens of locations with those from previous storms dating, in some cases, back to 1973.

At Clear Creek and I-45, Beryl flooding reached almost as high as Tropical Storm Allison (7.7 feet in Beryl vs. 7.8 feet in Allison).

HCFCD did not record any high-water marks in the Lake Houston Area.

Deaths

As of July 31, Hurricane Beryl had directly caused five deaths in Harris County: three from drowning, two from falling trees.

Additionally, the County recorded 13 indirect deaths: eight heat related, five recovery related.

The report notes that Beryl continues a recent trend of more fatalities occurring in the aftermath of landfalling storms than from the storms themselves.

I’m not quite sure what to infer from that. Is our preparation for flooding getting better? Or is our infrastructure maintenance getting worse?

For More Information

To read the full Final Report on Hurricane Beryl, click here. You can compare reports on other major storms here.

Posted by Bob Rehak on 8/5/24

2533 days since Hurricane Harvey and 28 since Beryl