A hot-spot analysis of subsidence in the Houston metro area during the period from 2016 to 2020 revealed total subsidence of up to 9 centimeters in some areas. Rates of subsidence approached 2 cm per year. (Two centimeters equals 0.8 inches. Nine centimeters = 3.54 inches.)
The scientific study, named “Surface Deformation Analysis of the Houston Area Using Time Series Interferometry and Emerging Hot Spot Analysis” appeared in a scientific journal called Remote Sensing. Authors included Shuhab D. Khan, Otto C. A. Gadea, Alyssa Tello Alvarado and Osman A. Tirmizi from the Department of Earth and Atmospheric Sciences at the University of Houston.
Correlating InSAR Data with Well Data
The authors correlated observations of surface deformation using interferometric synthetic aperture radar (InSAR) data with an analysis of 71,000 water and and 5,000 oil-and-gas wells in the Houston area. They collected the InSAR data over 5 years and the well data going back 31 years.
USGS calls InSAR an effective way to measure changes in land-surface altitude. The images are compiled by using radar signals with a very high degree of resolution bounced off Earth from orbiting satellites. By measuring the time for the signals to travel to earth and back, researches can measure altitude. And by superimposing images taken at different times, researchers can measure changes in altitude over time.
Documenting Link between Subsidence and Groundwater Pumping
Khan and his team sought to determine how much groundwater pumping contributed to subsidence (sinking ground). They performed the same analysis for oil and gas pumping.
The researchers found the greatest subsidence – which had not been previously reported – in some of the region’s fast-growing suburbs – Katy, Spring, The Woodlands, Fresno and Mont Belvieu. They identified groundwater pumping as the primary cause in the first four, and oil and gas pumping as the primary cause in Mont Belvieu.
Otto Gadea, a graduate student from Khan’s team is quoted in Phys.org as saying, “We determined for the suburbs that excessive groundwater extraction appears to be the primary driver of subsidence.”
Population Growth Drives Groundwater Pumping
With population growth, groundwater extraction has become more prevalent in the Houston area. But subsidence is no longer substantial in areas that regulate it through entities such as the Harris-Galveston Subsidence District.
The Appearance of Regulation as Cover for Private Interests
Website’s such as StopOurSinking.com have long linked excessive groundwater pumping in Montgomery County with a host of issues ranging from subsidence, flooding, pavement breaks, and foundation shifting to pipeline problems. However, the LSGCD Board has cherry-picked scientific evidence that supports unlimited groundwater pumping.
This latest study by the UH team will make that harder. It validates many of the claims StopOurSinking has made for years. Khan’s team even concluded that subsidence may even cause fault movement in the area.
Link to Fault Movement, Too
“If current ground pumping trends continue, faults in Katy and The Woodlands will likely become reactivated and increase in activity over time,” the authors write. No seismic activity is reported along these faults yet they say. They believe the movement is happening by “aseismic creep.” However, Khan and his team found evidence of fault activity in “damages to roads, buildings and other infrastructure in the vicinity of these faults. Displacement along some is measured by up to 3 cm/year.”
Posted by Bob Rehak on 10/12/22
1870 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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2022/10/20221012-Screen-Shot-2022-10-12-at-12.21.48-PM.jpg?fit=1180%2C1200&ssl=112001180adminadmin2022-10-12 20:23:112022-10-12 20:23:16New UH Study Finds Subsidence Increasing in Houston Suburbs
The SJRA never did let Lake Conroe rise to its allowable flowage easement. The water level in Lake Conroe peaked at 7 a.m., August 28, 2017, at 206.23 feet. The SJRA’s flowage easement is 207 feet.
Outflow exceeded inflow by 8:30 a.m. on the 28th and stayed that way for the duration of the storm. As the lake level declined, the lake had up to 3 available feet of storage capacity.
Yet the SJRA kept releasing, on average, 2X – 10X more water than it was taking in. At one point, the ratio exceeded 100:1.
Tracking the Release Down West Fork
Garfield notes that the discharge ramp up that began the evening of the 27th reached a peak discharge rate of more than 79,000 cubic feet per second (cfs) just before noon on the 28th. The discharge rate didn’t dip below 70,000 cfs until 4 a.m. on the 29th – more than 16 hours later.
Following in lockstep with the Conroe release, flow rates at downstream gauges ramped up, in lockstep. By lining up the peaks of gages downriver, you can literally see the water surging down the West Fork all the way to Lake Houston. (See left side of image above.)
Significantly, Garfield says, these gauges all showed flattening flow-rate curves before the release ramp up. Those curves then turned and steepened upward as the Conroe release pulse arrived at those gauges.
Timing and Impact of Release in Lake Houston Area
Peak flow at the Humble gauge was reached shortly after noon on the 29th, roughly 24 hours after peak discharge was reached at the dam and roughly 30 hours after the high-rate release ramp up began.
Kingwood Village Estates residents trying to escape as Harvey’s floodwaters rose. Twelve later died.
The level of upper Lake Houston, as measured at US59, rose an additional 7 feet during this period.
Significant additional flooding of Kingwood homes can be tied to this same period of increased discharge.
Flow rates measured at the Grand Parkway gauge and calculated at the Humble gage indicate a flow rate increase in this period of between 70,000 to 80,000 cfs, corresponding closely to the 79,000+ peak flow rate added by the Conroe dam discharge.
“The data from the affidavits further supports several key conclusions from the Harvey Flood Fundamentals section of our University of Houston talk,” said Garfield. Those include:
The large sustained release from Lake Conroe made West Fork flooding worse. The extra 80,000 cfs increased the West Fork flow 50%.
The release occurred as the storm was abating. It significantly increased flood damage in the Lake Houston area.
More than 4,400 structures flooded in Humble and Kingwood along the West Fork. Source: HCFCD.
The SJRA maintains to this day that Lake Conroe is a water-supply reservoir, not a flood-control reservoir. See the affidavits of Hector Olmos and Chuck Gilman. Olmos is a consultant who helped design the operations manual for the gates at Lake Conroe. Gilman is the SJRA’s Director of Flood Management, hired the year after Harvey.
They are basically claiming, “We don’t have the right tool to prevent downstream flooding.”
Editorial Opinion
Editorial opinion: That excuse has always sounded hollow to me. It attempts to curtail discussion of whether the SJRA waited too long to start releasing water, released too much at the peak, and then kept on releasing too much for days.
That discussion is a matter of public concern that could save lives and property in the future. We need to have it.
Sadly, it will take the courts to figure this out. In the meantime, the SJRA has hired some of the highest priced lawyers in the country and now appears to be angling for legislative immunity by hinting at higher water prices “statewide” if liability can’t be controlled.
Posted by Bob Rehak on 6/12/2020with thanks to Tim Garfield and RD Kissling
1018 Days after 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.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/06/Peaks.jpg?fit=1200%2C680&ssl=16801200adminadmin2020-06-11 22:29:342020-06-12 08:21:20What Happened Downstream During Harvey as Lake Conroe Released 79,000 CFS
Mark your calendar. On Wednesday, October 2, 2019, from 4:30 to 6:00pm, Tim Garfield, a Kingwood resident and one of the world’s leading geoscientists, will deliver a talk at the University of Houston. The subject: how the mouth bar of the San Jacinto West Fork contributed to flooding during Hurricane Harvey and what its continued presence means for the future of residents in the Lake Houston Area.
About the Speaker and Sponsor
Garfield has been one of the leaders in the grassroots movement to mitigate the influence of the mouth bar on flooding. The University of Houston History Department and Houston History Magazine have also led the movement to document the impacts of flooding on the development of Houston.
Event Details
The flier below gives more specifics about the talk.
Driving and Parking Instruction for the University of Houston Honors Commons
The event is free and open to the public. It will be held at the University of Houston Honors Commons. To learn how to get there, where to park and how to navigate from parking to the event, see below.
Debbie Z. Harwell, Ph.D., Assistant Professor of History at UH and the Editor of Houston History Magazine, arranged this event. Kudos to Garfield and Harwell for documenting the impacts of Harvey and geomorphic processes on the history of Houston.
This is one of those rare times when human history and geologic history intersect. Don’t miss it!
Posted by Bob Rehak on 9/14/2019
746 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/09/San-Jacinto-River-Mouth-Bar-Tim-Garflied-flyer-1.jpg?fit=1500%2C989&ssl=19891500adminadmin2019-09-14 19:37:482019-09-14 19:37:56UH Center for Public History Sponsors Talk by Tim Garfield on Influence of Mouth Bar on Harvey Flooding
Next week will mark the second anniversary of Hurricane Harvey. As we look back and build forward, we should also remember previous storms and how flooding shaped the a city called Houston and the people who inhabit it.
Houston History Magazine
In this regard, a reader forwarded me several links to a fascinating magazine. Debbie Z. Harwell, PhD., is managing editor of Houston History Magazine and a history teacher at the University of Houston.
Dr. Harwell was helping birth a new edition of Houston History focused on industrial accidents when Harvey hit. It was too late in her publication schedule to refocus the issue; she had been working on it for almost a year. So she wrote an introduction that helped put the storm in historical perspective. She wrote it sitting on a couch while Harvey’s rains beat against her windows.
Short-Term Memory Loss of Long-Term Needs
Prophetically, she titled the intro “Short-term Memory Loss of Long-term Needs.” In it, she says, “As a city and as a country we seem to suffer from short-term memory loss. Our memory of the flood is wiped out not by old age but by the next big news story, or even the next tweet. Past floods have similarly faded from the collective memory (until it happens again), with few willing to spend money on the necessary infrastructure to produce real change.”
Houston History also published a photo essay of Houston Floods called “Lest We Forget.” Former Houston Post photographer Joel Draut collected the photos and wrote the accompanying text. Interestingly, one of the most significant floods happened in 1837, one year before Louis Daguerre invented the first commercially viable photographic process, now known as the daguerreotype.
In an August 1836 advertisement, the Allen brothers proclaimed that Houston would become “ …beyond all doubt, the great interior commercial emporium of Texas.” Thirteen months later rains from a hurricane in September 1837 flooded the city’s Main Street to a depth of four feet. This inundation did not deter developers.
As I looked through page after page of forgotten photos from 1929, 1935, 1960, and 1973, I was struck by how similar they were to Harvey images. They were grainier. They were black and white. But aside from that, the images could have been from any one of a hundred more contemporary calamities, such as Katrina, Ike, Rita, or Harvey. Sometimes, even the dates were the same, like the Memorial Day flood of 1929 shown below. The location: Franklin and Milam. The bayou: Buffalo.
Photo courtesy of Houston History Magazine and Houston Metropolitan Research Center, Houston Public Library.
“Lest We Forget” is a short but great and sobering read. I highly recommend it.
Survivors, Volunteers, Responders Tell Their Harvey Stories
Dr. Harwell is also one of the driving forces behind a project called Resilient Houston: Documenting Hurricane Harvey. “We did an oral history harvest at the Kingwood Community Center last October,” said Dr. Harwell, “and excerpts from those interviews appear on the site. Almost half of those are from Kingwood – survivors, volunteers, responders. We will be adding more at the end of the fall semester.”
Posted by Bob Rehak on 8/22/2019with thanks to Dr. Debbie Harwell and Joel Draut
723 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/08/Memorial-Day-1929.jpg?fit=1500%2C993&ssl=19931500adminadmin2019-08-21 23:43:102019-08-22 09:12:56Lest We Forget: Houston’s History of Flooding
Aeschylus, the ancient Greek playwright coined the phrase, “The first casualty in war is truth.” The same is true of water wars. In an attempt to justify unlimited groundwater pumping from the Jasper aquifer, a headline in a Montgomery County online newspaper trumpeted, “University Of Houston Study Shows No Linkage Between Deep Groundwater Production And Subsidence In Montgomery County.” But wait! Is that what the study really said? The article did not provide a link to the actual study. So how could you tell if the review was accurate? It’s not. Below are just a few of the reasons why.
Contradictions Between Study and Newspaper’s Summary
The UH study didn’t study Montgomery County. It looked only at Harris-Galveston Subsidence District Regulatory Areas 1 and 2. They cover only SOUTHERN Harris and Galveston counties! Researchers found no subsidence associated with the Jasper there. That’s because virtually no one pumps the Jasper there (See Jasper well location map below). The article’s anonymous author forgot to mention that though.
“Don’t Extrapolate Results,” But They Did
The UH study also carefully cautions readers not to extrapolate the results from the study area to other areas. But the newspaper did it and forgot to mention the caution also.
Newspaper Falsely Claims Study Suggests “No Subsidence”
The newspaper author claimed that the study “suggests that Montgomery County utilities, municipalities, homeowner’s associations, and other large-scale groundwater users could draw water production from the Jasper aquifer without causing any subsidence at the surface of Montgomery County.” The UH study makes no such suggestion.
Claimed “No Need for Regulation,” Contrary to UH Findings
The newspaper author goes on to claim that the study “also suggests that, as long as groundwater production comes from the Jasper or lower formations (such as the Upper Catahoula Formation), there is little need, if any, for any groundwater regulation whatsoever.” Again, the UH study makes no such suggestion.
Quite the contrary, the UH study says that regulation was effective in slowing the subsidence found in other aquifers along the gulf coast that were being depleted, such as the Evangeline and Chicot.
Newspaper Claim of 100% Annual Recharge Not Substantiated by Study
The newspaper author also says that, “Since the quantity of groundwater in Montgomery County is essentially unlimited, and since Montgomery County aquifers enjoy almost 100% recharge annually after production drawdowns have occurred, there would seem to be no reason whatsoever to regulate groundwater production from the Jasper aquifer and the Catahoula aquifer.” The study makes no mention of recharge rates in either of those aquifers.
Newspaper Implies “No Need for Regulation” but Study Says It Helped
Finally, the anonymous newspaper author concludes by saying, “The University of Houston study suggests that it’s time for the Lone Star Groundwater Conservation District to bring the entire over-regulation of groundwater to a crashing halt.” The study made no such recommendation.
Inferring that the UH scientists even implied that would require turning the the study’s findings on their head. Quite the contrary. The study explicitly states that regulations implemented in 1975 with the formation of the Harris-Galveston Subsidence District slowed out-of-control subsidence.
Newspaper Article Not Signed
Jumpin’ Jasper! What’s going on here? Who wrote this unsigned article? Was it someone who stands to profit financially from pumping the Jasper dry?
Why Water Not Pumped From Southern Part of Jasper
For the record, the Jasper dips toward the coast along a roughly north-to-south axis. The Jasper aquifer contains fresh water in Montgomery County and northern Harris County. But south of that, it becomes brackish. The water is too salty to use. That’s a big reason why virtually no one pumps it in the southern part of the region.
This map shows the freshwater limits of the Jasper aquifer in 2010. For the most part, the freshwater portion of the Jasper aquifer does not extend to the area of interest studied by the UH scholars.
The down-dip part of the Jasper toward the coast also goes very deep. At the southern limit of freshwater, depth ranges to thousands of feet in places (see bottom of colored area below). Why would you drill that deep if you could get fresher water from aquifers like the Chicot and Evangeline much closer to the surface?
Subsidence Already Noted in Northern Part of Jasper
Those are the reasons why the UH scholars do not associate subsidence with the Jasper in southern Harris and Montgomery Counties. That does NOT mean subsidence won’t happen in other areas where utilities DO pump the Jasper. It already has.
However, USGS well-water height readings north of Highway 99 show severe drawdown near the population centers in southern Montgomery and northern Harris Counties. And surprise, surprise! That also happens to be the area where most subsidence has occurred in Montgomery County.
Unsustainable Pumping Rates
While the advocates of unlimited groundwater pumping want you to believe that the aquifer recharge rates in Montgomery County equal the drawdown rate, they don’t. The Jasper aquifer is being drawn down in populated places at more than 10 FEET per year (see graph below). But USGS estimates that the recharge rate for the Jasper is as little as ONE-TENTH of an INCH per year. That means some utilities have been using up Jasper water 1200 times faster than nature replaces it.
This well drilled in the Jasper aquifer near the Woodlands showed an average decline of approximately 10 feet per year (about 180 feet in 18 years).
Ground level declines produce fault movement and subsidence. They translate to infrastructure damage and flooding.
As water levels decline, water wells begin to have problems producing. They lose “yield,” which means they can’t produce as much water in a given time period. This requires the wells to run longer to meet demand. It costs more to lift water. Longer run times increase maintenance costs. Pumps have to be lowered. The motors have to be upsized, which requires electrical rewiring.
Some well pumps can’t be lowered any farther, which may mean abandoning and replacing the well. Some water level decline is expected. But those who argue that Montgomery County has an unlimited supply of water are just ludicrous. The harder you pump, the more decline you get, and with that comes all the consequences of declines.
Why People Want to Believe the Unbelievable
Montgomery County residents have found the change from well to surface water financially difficult. People WANT to believe that unlimited groundwater pumping is safe. I just hope they don’t wind up putting all their water lillies in one pond, so to speak.
Selective Perception Amplified by Selective Deception
Selective perception is a well known cognitive bias. It describes the process by which people perceive what they want to in media messages while ignoring opposing viewpoints. However, in this case, it seems that selective deception is amplifying the bias.
Don’t take my word. Read the newspaper article and then read the actual study on which the article is based. I provide links so you can make up your own mind; the newspaper article did not.
Other Useful References
Below are some other useful publications from the U.S. Geological Survey which is part of the Department of the Interior.
USGS Subsidence home page. Contains dozens of useful publications on Texas Gulf Coast Groundwater and Land Subsidence, plus raw data in numerous formats.
Note: All thoughts in this post represent my opinions on matters of public interest and safety. They are protected by the First Amendment of the U.S. Constitution and the Anti-SLAPP statute of the great State of Texas.
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/07/Screen-Shot-2019-07-26-at-12.33.30-AM-copy.jpg?fit=1500%2C715&ssl=17151500adminadmin2019-07-27 01:22:302019-07-27 02:27:17Truth is the First Casualty In Water Wars, Too
On August 24th, Dr. William R. Dupré , Professor Emeritus of Earth & Atmospheric Sciences from the University of Houston, gave a presentation at the Kingwood Community Center sponsored by the Houston Geological Society. The presentation is titled Flooding and Floodplains in the Houston Area: Past, Present, and Future. Professor Dupre’ has given ReduceFlooding.com permission to post his presentation. It consists of two parts. Together, they will help you understand how and why floodplains change over time.
Urbanization is just one of many factors cited by Dr. Dupré that increase flooding.
The Basics of Flooding, Floodplains and Measurement
The difference between drainage basins, networks and watersheds
How stream gages work
How and where to find flood data (USGS, SJRA, Harris County Flood Warning System)
How to compare hydrographs from different locations and assess your risk of flooding
The difference between annual recurrence intervals and annual exceedance probabilities
How to understand flood maps
Assumptions behind flood plain calculations
Different types of flooding (overbook, ponding, sheet flow, etc.)
At the end of Part 1, Dupré shows how some of these concepts apply to different watersheds within Harris County and discusses how flooding dangers differ in various parts of the County.
Changing land use, (i.e., urbanization, prairie restoration, etc.)
Structural changes (dams, levees, channelization and detention/retention basins)
Changing climate
Part 2 concludes with a discussion of changing approaches to flood control and a brief discussion of the recently approved Harris County flood bond.
Do Sand Mines Play a Role?
Part 2 includes a discussion of sand mining under “Causes of Changes in Sediment and Sedimentation. Dupré talks about different types of sand mines and their impacts. While the professor and I disagree about the interpretation of several satellite images, we agree wholeheartedly about the need to locate pits outside of a ‘channel migration’ zone, as regulations in Washington state and Arizona require.
The danger, he says, is that rivers can migrate to and through sand mine dikes. If this happens after abandonment of the mine, no one will me there to repair the dikes and the river will reroute itself through the pit, carrying stored sediment downstream.
Who Will Benefit from This Presentation
If you enjoy earth sciences, as I do, these presentations will feel like going back to college. If you’re simply a homeowner trying to figure out why you flooded, you’ll find lots of food for thought in these two presentations. If you’re debating whether to buy flood insurance, these presentations will make you a believer.
Key Messages
One of the key takeaways from Part 1 is that you should not think of the 100-year (1%) floodplain as a bright line where you’re safe on one of it and not safe on the other. Dupré calls that choice a “false binary.” He urges people to think of flood plains as ever shifting and flood plain boundaries as very fuzzy lines, much like the cone of uncertainty used for hurricane path prediction. The width of the line represents the margin of error behind the calculation of probabilities.
After reviewing Part 2, you should come away with a better appreciation for how gradual, almost unnoticeable changes in your environment can increase your flood risk.
Remember Flood Control Presentation At Community Center on 9/17
Matt Zeve, Director of Operations for Harris County Flood Control, will also discuss flood map revisions in his upcoming talk at the Kingwood Community Center on September 17 at 6:30. Don’t forget to mark your calendar.
Posted by Bob Rehak on September 11, 2018
378 Days since Hurricane Harvey and 17 years since 9/11
00adminadmin2018-09-11 17:09:482018-09-11 17:11:10Flooding and Floodplains in the Houston Area: Past, Present, and Future
