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New TCEQ Sand Mining BMPs Ignore Pit Captures

12/13/24 – Proposed new Texas Commission on Environmental Quality (TCEQ) Best Management Practices (BMPs) for sand mines ignore what miners are supposed to do in the case of pit captures. “Pit capture” happens when a river breaks through the dikes of a sand mine. It can have serious consequences including, but not limited to:

Increased erosion and river instability
Altered hydrology
Water quality degradation
Habitat loss and ecosystem disruption
Infrastructure risks
Channel realignment
Economic impacts (cost of mitigation)

Identifying Pit-Capture Pros and Cons

In some circumstances, pit capture can also produce benefits. The balance between benefits and risks depends on the specific geomorphological and ecological context of the river and the sand mine pit. To maximize benefits while mitigating risks, scientists recommend:

Performing a hydrological and ecological assessment before and after capture.
Using adaptive management strategies to guide the development of the captured pit.
Integrating the site into regional plans for flood control, habitat creation, or recreation.

However, the new TCEQ sand mine BMPs mention no such studies, despite the fact that at least six pits were captured on the East and West Forks of the San Jacinto during floods this year. Plus, consider this. The City is getting ready to spend another $34 million to dredge another million cubic yards of sand from the confluence of the two forks.

Instead, the new TCEQ BMPs emphasize concepts under headings such as “Be a Good Neighbor,” “Practice Good Housekeeping,” and “Select Appropriate Equipment.” This is stuff most guys learned in a middle school shop class. Under “Good Housekeeping,” one recommendation urges miners to adequately maintain sanitary facilities. But they forgot the “Wash hands after using a port-a-potty” requirement.

My overwhelming impression after reading the new BMPs was a yawn. Why bother?

The new BMPs are more notable for what they don’t include than what they do include.

And they don’t include anything about the B-52 sized elephant in the broom closet – pit capture.

*River now cuts through Hallett Pit on West Fork and has abandoned its original channel (right)*.

*Pit containing wastewater now has a more direct route to river when it breaches. Note repair by maintenance road.*

*The pit above is just one of many at the Hallett West Fork Mine which spans several square miles.*

I discovered the pit capture above in June of this year. It likely occurred in the May flood. And Hallett has done nothing to mitigate it since.

Perhaps they and the TCEQ feel the benefits outweigh the consequences. But of course, they aren’t footing the $34 million dredging bill.

In August of this year, TCEQ issued a report on another pit capture slightly downstream from here. It didn’t mention this pit even though it was open at the time and multiple people filed complaints. Nor did it mention the term “pit capture.” And the report made several other mistakes. For instance, Hallett claimed the expert witness TCEQ identified works for them, the but the TCEQ listed the employee as working for a Hallett competitor. No wonder the Texas Sunset Commission called TCEQ a reluctant regulator.

Leave a Public Comment

So what’s a mere citizen who enjoys clean water to do?

The TCEQ is soliciting public comment on their new BMPs for sand mines. I know what my comment will be about. If you wish to leave a public comment:

Feedback or comment must be provided to Jess Robinson, MC 175, Office of Legal Services, Texas Commission on Environmental Quality, P.O. Box 13087, Austin, Texas 78711-3087. Comments may also be submitted electronically. To be considered for this project, input must be received by 11:59 p.m. on January 24, 2025, and should reference “APO BMP List Proposal.”

Posted by Bob Rehak on 12/13/24

2663 Days since Hurricane Harvey

Educating People About a Healthy Floodplain Environment

12/12/24 – Karastin Katusin gets people to see, touch, and experience a healthy floodplain environment, so they will want to protect such places.

Katusin is a geologist and educator by training. She is also the Community Conservation Manager for the Bayou Land Conservancy, one of the leading environmental organizations in southeast Texas. Her mission: connecting people to nature and educating them about floodplains.

I interviewed Katusin recently about the Bayou Land Conservancy’s Arrowwood Preserve along Spring Creek. It’s one of her favorite places to teach. She frequently guides students and faculty from Lone Star College as well as community groups through this fragile ecosystem so they can experience the many ways nature can make us all healthier and safer from floods.

Giving Water a Safe Place to Go

Rehak: When you teach people how a healthy floodplain can help reduce flooding, what key points do you make?

Katusin: First, in order to have a healthy floodplain, you have to have a floodplain. I’ve lived in Texas now for eight years, and I still am amazed at how you can just build anything anywhere. So, I always try to point out to people that Arrowood, for example, is a great opportunity for us to not develop. The ecosystem is not yet as healthy as we want it to be, but it still gives water a safe place to go.

A two-inch rain along Spring Creek can produce flooding over your head in Arrowwood.
Karastin Katusin

During Hurricane Harvey, water in Spring Creek rose 26.5 feet! As development continues, we need to leave natural places for that water to go, so it doesn’t go into people’s living rooms.

*Group going down the main entry trail to Arrowwood* *to learn about floodplains.*

Same entry trail in winter after a small rain. Where did that hill go?

Teaching and Applying the Fundamentals

Rehak: What do you tell people to help keep them safe from flooding?

Katusin: The number one thing is “get educated.” Learn flooding concepts. A lot of people don’t understand the difference between a floodway and a floodplain. Or a one-year flood, a 10-year flood and a 100-year flood?

I often hear people say, “We just had a 100-year flood. So, how can we have another?” They don’t understand that it’s a statistical estimate that means you have a one-percent chance of flooding EVERY year. So, educating yourself is Step One.

And then Step Two is, “Do the work.” Figure out how these flooding concepts apply to your situation. For instance, people sometimes say, “Oh well. So what if I’m in the 50 year floodplain?”

Rehak: So what! Someone in a 50-year floodplain has a 44.5% chance of flooding during the life of a 30-year mortgage! That’s almost like betting your home on a coin toss.

Katusin: Absolutely. I don’t think they understand how dangerous that is. There’s a related concept called system capacity. Can the stream hold a rain of a certain intensity without coming out of its banks? For instance, a stream that has a 50-year system capacity can hold a 50-year rain without flooding.

Rehak: The Spring Creek watershed seems to be a land of extremes.

Katusin: Some parts have a 500-year system capacity. Others out there by 290, right where all the development is happening, have less than a 25-year system capacity.

How BLC Helps Protect People from Flooding

Rehak: So, how does Bayou Land Conservancy help protect people from flooding?

Katusin: Most people want land preserved for wildlife, water and flood control. But they don’t know how that happens. That’s where we can help. We work with landowners to reduce development on property they own. But we do it in a way that lets them still use their land in a productive way, keep it in the family, and save money.

The Value of Conservation Agreements

Katusin: Sometimes people donate land to us outright. But more often, they retain ownership of their land and we put conservation easements on it. The easements restrict the land from being used for development. But they still let the landowner use their land in other ways. For instance, agriculture, forests, hunting, camping, etc.

The agreement stipulates what each party can and can’t do. For instance, we won’t clearcut the land or put in a shopping center. Instead, we will try to create a pocket of land that ideally becomes a sponge for floodwater.

*Preserving wetlands helps store stormwater that would otherwise add to flood peaks downstream.*

It’s great when the public can access the land. But remember, in most cases, we just have a conservation easement. The original owner may still own the land and keep it in their family. That may limit public accessibility.

Rehak: How does the family make money off the agreement? How do they benefit?

Katusin: Often, landowners get some sort of tax break.

Rehak: Why?

Katusin: Because the land has lost some of its development potential, typically the tax valuation decreases.

Rehak: Like on the portion of the land along a creek in a floodplain?

Katusin: Exactly. It doesn’t make any difference to us if it floods. By preserving the land in a natural state, we’re giving water a safe place to go. Wildlife has a safe place to live. And hopefully, the land soaks up excess rainwater. That helps reduce flooding downstream.

Rehak: What do you like most about your job?

Katusin: I love explaining these concepts to groups … in a natural setting. I lead tours of our preserves when groups request them. It’s fun watching people connect all the dots and understand why it’s important to protect land along rivers and streams.

*Karastin (kneeling on left) with a BLC trail crew restoring Arrowwood Preserve.*

For More Information

To learn about the many ways you can support the mission of the Bayou Land Conservancy, visit their website.

Posted by Bob Rehak and Karastin Katusin on 12/12/24

2662 Days since Hurricane Harvey

Kingwood’s East End Park: Beautiful Flood Protection

12/11/2024 – One of the most popular parks in Kingwood is KSA’s East End Park. Tens of thousands of people visit this 158 acre, dog-friendly nature park each year. It’s spectacularly beautiful – filled with towering pines, tall-grass meadows, wetlands, boardwalks, wildlife, and miles of hiking trails.

Members of the Lake Houston Nature Club and the Houston Audubon Society have documented an incredible 141 species of birds in East End Park, many threatened or endangered. The list keeps growing thanks to KSA and community conservation efforts.

The park is especially popular for sunrise walks. The photo below shows why. The sunrises can be a deeply spiritual, rejuvenating experience.

alternative water source, East End Park — *Sunrise over Lake Houston from Kingwood’s East End Park at Otter Point. By Dr. Charles Campbell.*

Recreational Wonderland That Doubles as Flood Protection

The recreational benefits of the park are undeniable. But not many people realize that East End Park also plays an important role in flood mitigation.

Friendswood Development Company originally had plans to develop a subdivision where the park is today. But back in 1988, the EPA issued a cease and desist order to help preserve the wetlands. To make the most of the situation, Friendswood donated the land to the Kingwood Service Association (KSA). Friendswood hoped that KSA would turn the land into a recreational facility benefitting all Kingwood residents.

As the EPA intended, in their natural state, the wetlands help protect water quality in Lake Houston. They act as nature’s sponges, storing stormwater and eroded sediment before it reaches the lake.

But East End Park also turned into a buffer zone. And that’s the main way it reduces flooding – by keeping homes a safe distance away from floods.

Although a few surrounding residents flooded in Hurricane Harvey, keep in mind that the East Fork San Jacinto submerged the entire park. Harvey was an extreme case. But the buffer has worked for everything else.

Today, the biggest dangers come from occasional encounters with alligators, poison ivy and golden silk banana spiders. They are the largest non-tarantula spiders in North America. Many have leg spans more than five inches wide.

Golden silk banana spiders look ferocious. But they are gentle. And they are beneficial because of all the insect pests they eat including grasshoppers and locusts. However, a single female can spin a web across a ten-foot wide trail overnight. They are most prevalent in the late fall. Webs are usually 5 – 9 feet above ground. So, early morning joggers beware!

I wish the Houston area had more places like East End Park. We’d have healthier lifestyles and less flooding.

Posted by Bob Rehak on 12/11/2024

2661 Days since Hurricane Harvey

Northpark Expansion Still Making Progress Despite Holidays

12/10/24 – Halfway between Christmas and New Year’s, Harper Brothers Construction is still making progress on Northpark Expansion. The pace appears to have slowed somewhat. But that’s because of the current focus on subsurface drainage. Installing reinforced concrete box culverts takes significantly longer than work above ground.

It appears that all of the old westbound road bed between Caliber Collision and the railroad tracks has been removed except for driveways.

Meanwhile, farther east, I spotted more concrete being poured in the middle in preparation for additional demolition of westbound lanes.

Pictures Taken 12/10/24

*Looking east from just west of Russell Palmer. Note new concrete being poured in middle of frame.*

*Closer shot of today’s pour near Shipley’s*. Still looking east.

*Wider shot looking west shows significant progress where old drainage ditch used to be in center.*

*Installation of box culverts in front of Caliber Collision*. Notice: old road bed removed between here and railroad tracks.

The area above is where surface turn lanes will diverge from westbound traffic headed over an as-yet-unbuilt bridge over the railroad tracks.

*Coffer dam protects workers from cave ins as they work underground.*

Up Next

In other news, according to the Lake Houston Redevelopment Authority website:

Waterline crews will continue transferring water services from the Porter SUD to the City of Houston waterline.
Dirt crews will backfill new paving on Loop 494 and excavate for the asphalt transition on each end to tie into the new concrete paving
Next week, project managers have scheduled a traffic switch on LP 494. They will move all traffic onto the new concrete paving, and close off the existing LP 494.
Another traffic switch during the week of 12/16 will occur just east of Kings Mill to the east end of the project. Traffic will detour into the middle closing off the existing eastbound lanes.

To see what happens when, consult the Lake Houston Redevelopment Authority project pages or the schedule below.

For More Information

To learn more about the project history, consult these ReduceFlooding.com posts:

The next meeting of the Lake Houston Redevelopment Authority Board will be Thursday morning at 8am at the Kingwood Community Center.

Posted by Bob Rehak on 12/10/24

2660 Days since Hurricane Harvey

Addicks-Barker Litigation Update

12/9/2024 – Testimony concluded today in the latest appeal of the Addicks-Barker lawsuits arising out of Hurricane Harvey.

During Harvey, homes both upstream and downstream of the Addicks and Barkers Reservoirs flooded. Residents allege that the Army Corps’ management of gates on the reservoirs contributed to flooding their homes. The cases have wended their way through the federal court system almost since the storm flooded large parts of Houston’s west side.

Downstream Case

Previously, a trial court ruled against the downstream plaintiffs. The U.S. Court of Federal Claims held that plaintiffs did not have “a cognizable property interest in perfect flood control.” An appeals court disagreed. It sent the case back to the lower court for further proceedings.

The new downstream trial began on Friday October 25 at the Federal Courthouse in downtown Houston. It is a limited trial aimed at answering two questions from the judge:

(1) Was there an emergency that necessitated the United States Army Corps of Engineers (the “Corps”) opening the Addicks and Barker reservoir gates, or were the gates opened as a matter of ordinary operating procedure; and

(2) What would have happened if the gates had remained closed?

McGehee ☆ Chang, Landgraf, Feiler, attorneys for the plaintiffs in the Addicks-Barker cases, reported that they examined one expert witness and three fact witnesses on October 31, 2024. The witnesses included the former district commander of the Army Corps and the Corp’s chief of engineering for the district.

An expert witness for the plaintiff testified that: (1) There was no emergency involved in opening the flood gates. And (2) If the gates were closed, most of the downstream properties would not have flooded; and the duration and extent of flooding would have been reduced for those who would have inevitably flooded.

After testimony by two more expert witnesses, the next phase of the trial concluded today in Washington DC.

The plaintiffs’ attorney’s report that Corps’ staff “admitted that no emergency was ever declared by the Corps (during Harvey).” Also, plaintiffs’ attorneys say that “the Corps’ own expert witness had largely agreed that the majority of downstream properties would not have flooded if the gates had remained closed.”

Next Steps in Downstream Case

Plaintiffs will submit their post-trial brief summarizing their case to the Court on or before January 31, 2025. The government must submit its brief on or before February 25, 2025. Closing arguments are scheduled to take place in Houston on March 6, 2025, at 3:00 p.m.

There is no indication when the judge will make a final ruling.

Upstream Case

The upstream trial concluded in 2022. The government appealed on December 29th that year. On June 21, 2023, the government filed a 168 page brief, contending that:

The upstream flooding was caused by the unprecedented nature of Harvey rainfall – and not by the government’s actions
The government was trying to save life and private property – and that private properties are subject to the government’s “police power” (to protect public safety)
That the home owners are not entitled to recover certain categories of “damages” (such as lost profits and leasehold, displacement costs, personal property…etc).

Plaintiffs then responded to those claims in October 2023.

The court heard oral arguments from both sides on November 8, 2024. The government continued to claim that Harvey was a disaster that was a once in one-thousand-year occurrence, and that the government should not be penalized for this extremely rare event.

Plaintiffs contended that while Harvey was a significant rain event, it was not as infrequent as the government claimed.

Plaintiffs’ attorneys expect the court to issue its decision within another five months or so. That would ring the bell for the next round sometime in April or May of 2025.

Editorial Comment

We’re already more than seven years beyond Harvey, the event that triggered these lawsuits. Delays underscore the need for flood insurance; many homeowners will have likely died before the courts resolve these cases.

But flood insurance costs are rising rapidly. To help combat those rising costs, visit FloodSmart.gov. This FEMA-sponsored site gives you flood insurance quotes, connects you with agents, explains your flood risk, and discusses what to do before and after a flood. It also contains links to flood maps.

Posted by Bob Rehak on 12/8/2024

2659 Days since Hurricane Harvey

Dredge Still in Starting Blocks

12/8/24 – Callan Marine moved its dredge down the San Jacinto West Fork to a location between Atascocita Point and Royal Shores more than two weeks ago. But it hasn’t moved yet. Reasons for the delay are unclear at this point.

Still Anchored in Same Spot

This morning, the rain let up long enough to get some drone shots. Unfortunately, it appears that the dredge hasn’t moved since November. It’s anchored in the same spot in the same position as on November 23, 2024. To borrow a phrase from track and field, it hasn’t gotten out of the starting blocks.

There was no sign of any dredge pipe south of FM1960, where Callan had reportedly purchased some property for a disposal site according to a City spokesperson.

The dredge was anchored with its bit up, surrounded by tugs and pontoons.

*Tugs and pontoons with supplies and an excavator surround the dredge.*

*Dredge was anchored with bit up between Royal Shores and Atascocita Point on West Fork.*

Callan has welded several sections of dredge pipe together. They are strung out along a channel that connects the East and West Forks south of Royal Shores.

*See one long section of pipe on the left and two shorter sections on right.* *Atascocita Point on far shore.*

Reason for Pause Uncertain

A source familiar with the dredging industry suggested that delays might have to do with the placement area not yet being ready to receive spoils. But that’s speculation. I hope to learn more in coming days.

Purpose of Project

The purpose of the project is to help remove sediment that restricts the conveyance of the river system and also to help restore some of Lake Houston’s dwindling volume.

Former City Flood Czar Stephen Costello outlined the program approximately a year ago. The City plans to spend $34 million to remove almost 900,000 cubic yards of sediment east of Atascocita and south of the convergence of the East and West Forks.

Posted by Bob Rehak on 12/8/2024

2658 Days since Hurricane Harvey

Bayou Land Conservancy Volunteers Protect Nature’s Flood Protection

12/7/24 – One of the leading environmental groups in the Houston region is the Bayou Land Conservancy (BLC). Their motto: “We preserve land along streams for flood control, clean water, and wildlife.”

Last year, BLC volunteers logged thousands of hours maintaining and improving natural areas and trails that help others appreciate nature’s wonders.

One such volunteer is Jeff Hodges. He helped restore land along Spring Creek in BLC’s Arrowwood Preserve, which is being used for environmental education. His story is a testament to the tenacity of BLC volunteers in their service of nature. Below are excepts from Hodges’ responses to my questions.

Preserve’s Contribution to Flood Reduction

Rehak: How does the Bayou Land Conservancy help reduce flooding?

Hodges: Development in the Houston area will continue. We need to understand how this can lead to increased flood risk of flooding if not managed correctly.

BLC is a land trust. It protects lands where rain water is absorbed and held as flood waters, slowing down the release of water into creeks, streams and rivers. That helps reduce or eliminate flooding downstream.

These lands are increasingly important. They let water soak into the land providing much needed water, to the water table and aquifers.

Currently, ever major aquifer in the U.S. is being depleted, except in the Pacific Northwest. This depletion contributes to subsidence, which increases flood risk. Areas in the Woodlands have lost two feet of elevation from subsidence.

The lands that BLC protects also provide habitat for wildlife and give people a chance to enjoy nature.

Rehak: Specifically, how does Arrowwood reduce flooding along Spring Creek.

Hodges: Arrowwood is a natural flood plain. It slows and stores rainwater flowing toward Spring Creek. A large portion of the preserve floods in heavy rains. It gives stormwater someplace to sit and wait instead of moving quickly downstream and flooding other areas already developed.

Restoring the Natural Environment

Rehak: I hear that in trying to make Arrowwood more user friendly, you and your fellow volunteers removed more than a mile of silt fence. How did it get there?

Hodges: A sand-and-gravel company installed the silt fence when it applied for a permit to turn the property into a quarry. But neighbors blocked approval of the permit. The mining company, after a number of years, donated the land to Bayou Land Conservancy.

Rehak: Removing that silt fence must have been a chore!

Hodges: We actually made a short movie about it. The preserve comprises 117 acres and the fence surrounded 22 acres. As work began to make the preserve accessible, we realized that we did not have the correct equipment to remove the silt fence.

*Bayou Land Conservancy Volunteer Jeff Hodges led the Arrowwood Silt Fence Removal Project*

We originally estimated the preserve had 2 miles of silt fencing containing approximately 700 posts, each weighing 5 pounds.
Jeff Hodges

The task seemed overwhelming. But we were very concerned about the impact of the fence on wildlife. Turtles and other small wildlife couldn’t get over or around it.

Volunteers Discover Task is Herculean

Rehak: What kind of problems did you encounter?

Hodges: I started to wonder if we could remove the silt fence manually. Bayou Land Conservancy gave me and a small team permission to work on it. The first day, two of us tried to develop a process to remove the silt fencing. In a half day, we could only remove about 10 posts and 50 feet of fencing.

Most of the posts had to be dug out by hand. Each was four feet and originally pounded into the ground to a depth of two feet. But over time, silt built up around the fence. Many sections were totally buried.

The silt fencing has three components: posts, heavy metal fencing, and a plastic tarp. The combination prevents silt, sand and rocks from washing into the creek.

After the first day, most people would have been discouraged. But our volunteers proved it could be done. It was just going to take a lot of time and effort.

*Volunteers decided to separate the fence and post removal operations to speed things up.*

We decided we would remove the metal fence along with the black tarp first. We left the posts until we were able to develop a better way to remove them.

But the removal of the fencing was not without problems. Portions of the fencing were buried, so we had to dig them out. Worse, the fencing had become overgrown. Before we could remove it, we first had to remove fallen trees, and cut away vines and brambles.

Triumph of Ingenuity, Sweat and Safety Goggles

Rehak: Did you ever develop a faster system?

Hodges: As we removed fencing over the next couple of months, we worked on developing a technique to remove posts without digging. Eventually, we developed a technique that sped up the operation. We hit the posts with a sledge hammer on all four sides to loosen them. Then we hooked up a farm jack to pry them out of the ground.

Working as a team, we could remove about 15 posts per hour. Some, buried to the top in heavy clay, still had to be dug out by hand. Those just took longer.

Everyone working on this project had to wear long pants, long sleeves, safety glasses, and heavy-duty work gloves. We also had to be up to date on our tetanus shots, too for obvious reasons.

Rehak: What did the final boxscore say?

Hodges: All in all, the team ended up removing 499 posts and more than 1.5 miles of fencing. While working on the fencing, we also removed trash and litter which seemed to be everywhere. Fencing and trash filled two industrial dumpsters.

*Some of the trash and fencing materials removed from the BLC Arrowwood Preserve.*

It was grueling work. But the transformation of the land is overwhelming. And very satisfying. The beauty of what this preserve will become is now evident.

Postscript: Jill Boullion, Bayou Land Conservancy Executive Director, said, ““Jeff was awarded our Trailblazer Award for 2024 because of his leadership on this project. It’s an important part of our restoration plan for Arrowwood that will make the preserve even more ecologically valuable for the community. We appreciate volunteers like Jeff and the crew that did this very difficult project.”

Posted by Bob Rehak and Jeff Hodges on 12/7/24

2657 Days since Hurricane Harvey

Can Cypress Creek Stormwater Detention Offset SJRA Releases from Lake Conroe?

12/6/24 – When you look at Harris County Flood Control District (HCFCD) spending figures, it’s clear they are making a major flood-mitigation investment along Cypress Creek. At the end of the third quarter this year, HCFCD had spent more than $190 million on Cypress Creek projects since Hurricane Harvey. That was enough to rank it second among all Harris County watersheds. Only Brays Bayou received more funding.

Cypress Creek Stormwater Detention Basin at TC Jester — *New stormwater-detention basin under construction in September 2023 at Cypress Creek and TC Jester.*

So I asked how much the county’s investment in stormwater detention basins along Cypress Creek could help offset future releases from Lake Conroe by the SJRA during flood events.

Of course, any detention upstream helps offset flooding downstream. So the question is really “Can additional detention offset SJRA releases significantly?”

“Not a 1:1 Storage Question”

Harris County Precinct 3 Senior Project Manager Eric Heppen, P.E., PMP, explained how a professional engineer would answer my seemingly innocent question. It’s far more complex than it looks.

“Significantly” masks several layers of complexity.

For instance, how:

Much can Lake Conroe release compared to the total detention along Cypress Creek?
Fast is the SJRA releasing from Lake Conroe?
Long would the SJRA release last?
Much does the water spread out before reaching Lake Houston?

And then there are the questions of rainfall distribution and the arrival time of peaks. Is it raining as hard along Cypress Creek as it is above Lake Conroe’s dam? What if the flood peaks don’t arrive simultaneously?

For all these reasons, said Heppen, “It’s never going to be a 1:1 storage question. From a Lake-Houston-Area perspective, you can’t say that an acre foot of water held back on Cypress Creek exactly equals an acre-foot of water released from Lake Conroe.” Then he went on to answer my question as best he could given the uncertainties involved.

Comparison of Total Stormwater Detention

Heppen began by pointing out that studies show Cypress Creek needs another 25,000 acre-feet of floodwater storage. “Our initial goal is to add another 12,000-14,000 acre feet,” he said.

Lake Conroe, on the other hand, has a surface area of 21,000 acres. And the SJRA has an easement that gives it the ability to raise the lake six feet. For comparison, that’s 126,000 acre feet of additional detention, roughly 10X more than the detention volume being added to Cypress Creek initially or 5X more than the desired 25,000 acre feet.

So additional Cypress detention, when complete, would equal 10-20% of the variable storage that SJRA has to work with at Lake Conroe. That can make a dent in Lake Houston Area flooding.

Comparison of Release Rates and Durations

However, Heppen did not stop there. He also calculated how long Cypress Creek’s additional detention could offset releases from Lake Conroe. “IF the dam releases at 6,000 cubic feet per second (CFS) then that is approximately an acre foot every 7 seconds or so,” said Heppen. “That would mean SJRA was releasing approximately 500 acre feet per hour.”

“So…very, very, very simplified, if Harris County adds 10,000 acre feet along Cypress, and Lake Conroe releases 6,000 CFS, then the additional detention along Cypress Creek could take the increased release rate for nearly 20 hours,” added Heppen.

Compare that to actual release rates during a large flood. Affidavits by SJRA engineers show that releases above 70,000 CFS from Lake Conroe lasted 26 hours during Harvey.

Shaving 6,000 CFS off those releases for 20 hours could well have saved many homes and businesses on the periphery of the flood.

Conclusion: Blunted Peaks

The initial 12,000 to 14,000 acre feet of stormwater detention being added to Cypress Creek could have blunted the peak of Harvey had it been there at the time. The desired 25,000 acre feet would have made an even greater impact.

Of course, flooding is all about timing, i.e., when peaks arrive. But if the Lake Conroe and Cypress Creek peaks arrived at the US59 bridge simultaneously, the Cypress Creek storage could have reduced the combined peak significantly in my opinion.

Additional upstream detention was one of the three main goals advocated by the Lake Houston Area Task Force after Harvey. And I, for one, am all for the improvements being made to Cypress Creek stormwater-detention capacity.

Posted by Bob Rehak on 12/6/2024

2656 Days since Hurricane Harvey

Tsunamis, Storm Surge Demonstrate Power of Moving Water

12/5/2024 – Tsunamis are huge waves caused by earthquakes. Storm surge is a huge wave caused by hurricane winds. Both have unimaginable destructive power.

Bolivar after Ike — *Destruction on Bolivar Peninsula from Hurricane Ike* *storm surge in 2008.*

West Coast Tsunami Warning This Morning

This morning, a magnitude 7.3 earthquake struck Northern California. That caused the National Weather Service to issue tsunami warnings from Oregon down to San Francisco and beyond.

About three hours later, the warning was cancelled without explanation. Since then, significant aftershocks ranging from 3.0 to 5.3 magnitude have occurred. We will learn more in coming days.

Different Types of Earthquakes Trigger Different Tsunami Threat Levels

Massive earthquakes don’t always trigger massive tsunamis. The magnitude 7.9 quake that destroyed much of San Francisco in 1906 reportedly produced a wave height of only three inches. Small localized, underwater landslides created 1-2 foot waves, but their destruction was confined to small areas.

Geology determines, in large part, the height of a tsunami. Imagine two different types of geologic faults.

In a thrust fault, one tectonic plate is forced under another, pushing it up and causing a vertical displacement of the seafloor. This type of fault commonly generates a tsunami.

However, a strike-slip fault causes a lateral displacement. Land along a fault moves in opposite directions without causing elevation changes. Strike-slip faults typically do not generate tsunamis because they generally do not displace large volumes of water. (Contrast the animations in the two links above.)

Other factors may also affect tsunami formation. They include:

Depth: Shallow earthquakes (occurring at depths less than 70 km) are more likely to cause tsunamis than deep earthquakes, as the energy has a more direct impact on the seafloor.
Seafloor Topography: The configuration of the ocean floor, including ridges and trenches, can amplify or reduce tsunami formation.
Underwater Landslides or Underwater Volcanic Activity triggered by the earthquake can also contribute to tsunami generation.

In summary, while massive offshore earthquakes increase the risk of tsunamis, they do not guarantee one will occur.

In this case, officials issued the tsunami warning out of an abundance of caution when seismographs first detected the earthquake. Later, they cancelled the warning when it became clear no massive waves threatened. They made the right call initially. Here’s why.

Record Waves, Record Destruction

Some massive earthquakes, like the magnitude 9.0, 2011 Tōhoku earthquake in Japan, did produce devastating tsunamis. One wave reached more than six miles inland. A 48-foot high tsunami wiped out a nuclear power plant at Fukushima. And the death toll ultimately reached almost 20,000 people.

So you can imagine why California officials immediately issued warnings today for residents to evacuate to higher ground.

During the great Galveston hurricane of 1900, a giant wave of water caused by storm surge, not a tsunami, inundated the island with 8- to 12-feet of water. It killed an estimated 6,000 to 12,000 people.

One cubic foot of seawater weighs 64 pounds. Imagine getting stuck by tens of thousands of cubic feet. That’s why storm surge is the leading cause of death associated with tropical events, according to the National Weather Service.

Don’t take either storm surge or tsunamis lightly.

Elevation: Key to Survival

The National Weather Service’s Tsunami Warning Center offers an excellent FAQ page concerning tsunami warnings.

Interestingly, shortly after NWS issued the tsunami warning for the San Francisco area this afternoon, I had a huge spike in traffic on ReduceFlooding.com. Everyone was going to a post with the headline “Easy way to find the elevation of your home and the slopes around it.“

I notice the same spike in traffic every time floods threaten. People want to know whether they live higher than the expected crest of the flood, storm surge or, in this case, tsunami.

Published in 2020, the post has received more than 150,000 page views already this year. The biggest peaks were during the May storm, Beryl, Helene and Milton.

Ironically, when I wrote that post about elevation, tsunamis were the furthest thing from my mind.

Even more ironic, shortly before the warning, someone emailed me asking whether I thought a development near the San Jacinto West Fork was safe from flooding. I replied to her that if she had a concern about flood risk, she should buy on the highest ground she could afford, as far from the water as she could get.

Posted by Bob Rehak on 12/5/2024

2655 Days since Hurricane Harvey

System Capacity Maps for Harris County Channels Reveal Widespread Problems

12/2/24 – System capacity maps for each of Harris County’s 23 watersheds show widespread problems and raise questions about whether the county’s most severe needs are confined to historically underserved areas.

Harris County Flood Control District (HCFCD) released the maps in response to a Freedom of Information Act (FOIA) request.

What “System Capacity” Means

System capacity reflects the ability of a stream or channel to handle rainfall of different intensities before coming out of its banks. The way system capacity is expressed also reflects the expected frequency of over-bank events.

A channel that can hold a:

100-year rainfall has a 1% system capacity
50-year rainfall has a 2% system capacity
25-year rainfall has a 4% system capacity, etc.

“1% system capacity” indicates that the infrastructure is designed to handle the peak flow or volume associated with a 1% event without causing overflow or flooding.

One Key Part of Comprehensive Flood-Risk Picture

System-capacity maps are one piece of information used in determining a comprehensive view of flood risk. They help you quickly spot areas that need closer examination.

Other key factors used to determine flood risk include: topography around the channel, the elevation of a structure, degree of development in an area, building codes in effect when an area was built, population density, and more.

Impact of Atlas 14

The maps released today rely on pre-Atlas 14 data. Harris County did not provide current maps. Nor do they reflect improvements made to channels recently. But the older maps are still instructive because they formed the starting point for spending billions of flood-mitigation dollars. However…

Because these maps are based on old rainfall standards, today’s true system capacity is actually lower than shown.

Said another way, the situation on the ground is worse than the maps show. That’s because the transition from pre-Atlas 14 to Atlas-14 data in Harris County resulted in significant increases in estimated rainfall depths for various storm events.

Notably, the 1% annual exceedance probability (AEP) 24-hour rainfall depth—commonly referred to as the “100-year” event—experienced substantial changes.

Prior to Atlas 14, Harris County was divided into three hydrologic regions with the following 100-year, 24-hour rainfall depths:

Region 1: 12.4 inches
Region 2: 12.8 inches
Region 3: 13.5 inches

With the implementation of Atlas 14, these values increased to:

Region 1: 16.3 inches
Region 2: 16.9 inches
Region 3: 18.0 inches

This represents increases of approximately 31%, 32%, and 33% for Regions 1, 2, and 3, respectively.

These updated figures reflect a more accurate understanding of rainfall patterns, incorporating additional years of data and improved analytical methods. Consequently, infrastructure design and floodplain management practices in Harris County have been adjusted to align with these revised estimates, enhancing resilience against flooding events.

Value of Maps Based on Old Rainfall Standards

Still, these maps have value. They are a starting point for the $2.5 billion 2018 Flood Bond. They also show that:

All watersheds have problem areas
Channel capacity in some areas is extremely low
Some watersheds that are not “historically underserved” have more severe system-capacity issues than those that are underserved.

System Capacity Maps

Below are low-resolution maps for each of the 23 watersheds in Harris County. For high-resolution maps of all watersheds in one file, click here. Caution: [26-meg download.]

Correlation of Maps with Spending

It’s instructive to correlate HCFCD flood-mitigation spending with these maps. Below is where more than $2 billion has gone since Hurricane Harvey, in large part, to address the problems shown above.

Spending by Watershed since Harvey — *Data supplied by HCFCD. Shows relative spending by watershed since Harvey through Q3 2024.*

*HCFCD spending by watershed through Q3 2024 since Harvey in dollars.*

Compare the maps with the spending. And use the contact form of this website to let me know if you feel your area is not getting its fair share of flood-mitigation funding.

Note on Next Update with Atlas 14 Data

I have tried to get accurate flood risk data for years. However, HCFCD says it does not routinely update these maps every time it completes a new construction project. The District says it may update them again as part of the MAAPnext project after FEMA approves new maps based on Atlas-14 data.

Posted by Bob Rehak on December 2, 2024

2652 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.