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
Harris County Flood Control District (HCFCD) transmitted an update to Commissioners Court today that shows the progress of the flood bond through September 2022. The report shows slowing activity. Specifically:
No new construction contracts or other agreements were awarded in the last month.
Total spending increased only $21 million – from $1.104 billion to $1.125 billion.
Overall progress remained unchanged from August. It’s holding at 23.5% complete.
The amount of “Professional Services Invoices Paid” declined from $4.8 million to $1.7 million.
Home buyouts “in progress” declined from 331 to 305 (-26).
Improvements Since Harvey
The update also included a list of accomplishments since Harvey. HCFCD has:
Completed 229 project components, reducing the risk of flooding for more than 14,000 homes and businesses
Removed an estimated 4.7 million cubic yards of sediment from channels across Harris County through maintenance efforts – the equivalent of approximately 335,000 dump truck loads – to ensure stormwater can move through channels efficiently
Acquired more than 21,500 acres of land for projects, floodplain preservation and buyouts to ensure floodwaters can spread out safely without structures that can flood
Secured more than $1.35 billion in partnership funding while pursuing more funding opportunities at the federal, state and local levels.
Started the third batch of major maintenance activities along Cypress Creek.
Where Money Has Gone
Note that the September update (reported in October) actually contains figures compiled through the end of August. The map below shows where more than $1.1 billion has gone.
From Page 9 of September HCFCD Flood-Bond Update
Budget Priorities
Here’s how that spending looks in table form arranged in order from highest to lowest based on spending through the end of August (column 3).
This spending shows a huge disparity among watersheds. The ratio between Brays and Vince is 335 to 1.
The table also shows the effect of “equity prioritization” – concentrating on watersheds with a high percentage of low-to-moderate income (LMI) residents.
Eight LMI watersheds have received a total of $447.5 million for an average of $55.9 million each.
Yet the 15 otherwatersheds have received a total of $460.2 million for an average of $30.7 million each – roughly half as much.
The entire Lake Houston Area still has only two active capital improvement construction projects – valued at $1,000 each. Both are Excavation and Removal Contracts – one in Woodridge Village and the other in the Cedar Bayou Watershed.
Slowdown in Spending Bears More Investigation
The most worrisome aspect of this update is a continued slowdown in activity. At the current rate of spending, HCFCD would spend less than half the money in the bond in the next six years. Remember, we’re four years into a ten-year, $5 billion program. At $20 million per month for the next 60 months, HCFCD would spend only another $1.2 billion. That would cover only about half the projects in the bond.
However, note that in project management, sometimes pauses are built into projects for things such as approvals, right-of-way acquisition, etc. The real question is whether such pauses can explain the current slowdown. HCFCD is investigating to see how much, if any of the slowdown, is planned. More on that next month.
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/2022/10/20221011-Screen-Shot-2022-10-11-at-10.50.19-AM.jpg?fit=1200%2C913&ssl=19131200adminadmin2022-10-11 15:05:592022-10-11 15:32:06September 2022 Flood Bond Update
Splendora is exploding with growth. On FM2090 west of U.S.59 near the Splendora High School, two new developments have already cleared 598 acres and have another 611 to go. Together, they could easily quintuple the population of a rural town that only had 1900 residents in the last census.
Development Well Underway
I first covered this story in January. The developers have made remarkable progress since then. Townsend Reserve, Ltd. and Forestar USA, have built drainage, utilities, stormwater detention basins, roads and model homes on most of the land already cleared. Now, they’re building the first homes for sale. Rural, sleepy Splendora will soon change forever.
Forestar USA has named its development Presswoods. Townsend Reserve USA has simply called its Townsend Reserve.
Looking east along FM2090 at expanse of two developments. Splendora High School on right.
Closer Look at Detention Basins
Close up from shot above. Two detention ponds in Presswoods by Forestar USA bracket Gully Branch. Gully Branch drains into Peach Creek and eventually the East Fork of the San Jacinto.Another Forestar USA detention basin in the foreground.Looking West.Looking NE at a fourth detention basin on Townsend Reserve that parallels Gully Branch.Entrance to Townsend Reserve from FM2090 on right.Note yet another long detention basin that parallels the entry road on the left.Looking NW toward FM2090.First of the new homes going up.
Three things strike me about these photos.
Stormwater detention basins everywhere you look. Let’s hope the volume is sufficient. Engineers based their calculations on pre-Harvey runoff estimates. As other developers clear additional forests beyond these, drainage assumptions could change radically.
Huge financial risk. As interest rates continue to climb, will there be buyers for these homes?
Vast expanse of forests surrounding the developments. They seem endless. But not for long.
People hoping to find a quiet life in the country are gobbling up the very thing they seek.
Maybe this is inevitable. Developers tell me that smaller lot sizes and higher density don’t allow them to preserve trees anymore. Builders just plant one in the front yard when they’re done.
Population Impact
It’s not exactly clear yet how many homes the developers hope to build here. But in the last census, Splendora’s population was only 1,900 people. Even if they just built 5 homes per acre on 800 developable acres and the average household size was 3, that would mean 12,000 people could live here – more than 6X the current population.
Posted by Bob Rehak on 10/10/22
1868 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/2022/10/20221009-DJI_0877.jpg?fit=1200%2C799&ssl=17991200adminadmin2022-10-10 13:06:522022-10-10 19:10:07Splendora Development Exploding
New UH Study Finds Subsidence Increasing in Houston Suburbs
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
Other counties have set up entities to regulate ground water withdrawal, such as the Lone Star Groundwater Conservation District (LSGCD) in Montgomery County. However, the elected board chose not to include a subsidence limit in its desired future conditions. Many of the board members were backed by money from Quadvest, the area’s largest private groundwater pumper.
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.
September 2022 Flood Bond Update
Harris County Flood Control District (HCFCD) transmitted an update to Commissioners Court today that shows the progress of the flood bond through September 2022. The report shows slowing activity. Specifically:
Improvements Since Harvey
The update also included a list of accomplishments since Harvey. HCFCD has:
Where Money Has Gone
Note that the September update (reported in October) actually contains figures compiled through the end of August. The map below shows where more than $1.1 billion has gone.
Budget Priorities
Here’s how that spending looks in table form arranged in order from highest to lowest based on spending through the end of August (column 3).
This spending shows a huge disparity among watersheds. The ratio between Brays and Vince is 335 to 1.
The table also shows the effect of “equity prioritization” – concentrating on watersheds with a high percentage of low-to-moderate income (LMI) residents.
Eight LMI watersheds have received a total of $447.5 million for an average of $55.9 million each.
Yet the 15 other watersheds have received a total of $460.2 million for an average of $30.7 million each – roughly half as much.
The entire Lake Houston Area still has only two active capital improvement construction projects – valued at $1,000 each. Both are Excavation and Removal Contracts – one in Woodridge Village and the other in the Cedar Bayou Watershed.
Slowdown in Spending Bears More Investigation
The most worrisome aspect of this update is a continued slowdown in activity. At the current rate of spending, HCFCD would spend less than half the money in the bond in the next six years. Remember, we’re four years into a ten-year, $5 billion program. At $20 million per month for the next 60 months, HCFCD would spend only another $1.2 billion. That would cover only about half the projects in the bond.
However, note that in project management, sometimes pauses are built into projects for things such as approvals, right-of-way acquisition, etc. The real question is whether such pauses can explain the current slowdown. HCFCD is investigating to see how much, if any of the slowdown, is planned. More on that next month.
To see the complete bond update, click here.
Posted by Bob Rehak on 10/12/22
1169 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.
Splendora Development Exploding
Splendora is exploding with growth. On FM2090 west of U.S.59 near the Splendora High School, two new developments have already cleared 598 acres and have another 611 to go. Together, they could easily quintuple the population of a rural town that only had 1900 residents in the last census.
Development Well Underway
I first covered this story in January. The developers have made remarkable progress since then. Townsend Reserve, Ltd. and Forestar USA, have built drainage, utilities, stormwater detention basins, roads and model homes on most of the land already cleared. Now, they’re building the first homes for sale. Rural, sleepy Splendora will soon change forever.
Here’s the layout and photos of work in progress.
Forestar USA has named its development Presswoods. Townsend Reserve USA has simply called its Townsend Reserve.
Closer Look at Detention Basins
Three things strike me about these photos.
People hoping to find a quiet life in the country are gobbling up the very thing they seek.
Maybe this is inevitable. Developers tell me that smaller lot sizes and higher density don’t allow them to preserve trees anymore. Builders just plant one in the front yard when they’re done.
Population Impact
It’s not exactly clear yet how many homes the developers hope to build here. But in the last census, Splendora’s population was only 1,900 people. Even if they just built 5 homes per acre on 800 developable acres and the average household size was 3, that would mean 12,000 people could live here – more than 6X the current population.
Posted by Bob Rehak on 10/10/22
1868 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.