Groundwater relates to flooding? Yes. Here’s how. And here’s why you should care, especially now.
In November, Montgomery County voters will elect board members to the Lone Star Groundwater Conservation District who may advocate using more groundwater, a move that some believe could give residents cheaper water in the short run, but which could also cause subsidence, contribute to flooding, create shortages, raise costs and limit growth in the long run.
Subsidence is scientifically well documented and understood. Removing groundwater from clay causes the clay to compress. When that happens, you sink. And once clay is compressed, it stays compressed forever – even when rehydrated.
Yet some Montgomery County voters are advocating removing more groundwater because, at this moment, it’s cheaper than surface water. They are betting their future and their neighbors’ futures on it.
In 1944, the area that would become Brownwood in Baytown was starting to show signs of development.
By 1978, Brownwood was well developed…and sinking fast.
Today, the area floods so much that it is uninhabitable. All the homes are gone. Brownwood has been turned into a park.
The “Pump-Now, Let-Somebody-Else-Pay-Later” Mentality
Subsidence generally happens so slowly that some people claim it’s not a problem. Especially those on higher ground. They want to continue to pump water from their wells because they perceive it to be cheaper than surface water. It can be…at least in the short run..until wells run low or dry. Then pumping costs increase…often along with salinity…and the people who depend on the well are out of water and out of luck.
Gulf Coast Aquifers: Source Harris-Galveston Subsidence District. Much of the water in Montgomery County used for human consumption is pumped from the Jasper aquifer.
Depleting at More Than 500X the Recharge Rate
Still, some people say, “I’ll worry about that when it happens.” Problem is:
We’re depleting aquifers much faster than they’re recharging.
That means it could take 26,880 years (10 x 12 x 224) to recharge the Jasper groundwater that residents will use in just 50 years.
The rate of depletion will exceed the rate of recharge by more than 500X.
More Expensive in Long Run
Now consider this. As pressure in an aquifer decreases, the cost of bringing water to the surface increases dramatically, sometimes to the point where recovery is no longer economical, i.e., competitive with surface water. It’s much like the oil industry. As a rule of thumb, half the oil in reservoirs is left in the ground because it’s too expensive to recover.
For all these reasons, most counties in the region are trying to switch people to surface water. Their groundwater withdrawals have either declined or stayed the same.
Counties surrounding Montgomery have either decreased groundwater pumping or kept it constant.
Meanwhile, Montgomery County’s groundwater withdrawals have soared.
Montgomery County groundwater pumping, however, has generally increased in the last three decades.
The surge in Montgomery County groundwater usage is largely because Montgomery County has grown so quickly. With the exception of Fort Bend County, Montgomery County is growing faster than any county in the region on a percentage basis.
Houston Region growth last year by county. In percentage terms, Montgomery County trailed only Fort Bend County.
If Montgomery County expects to grow that fast in the next 50, where will the water come from to support that growth? Especially if voters undermine the financial viability of the half-billion dollar surface-water treatment plant – that they just built – by shifting to groundwater!
Proponents of unlimited groundwater pumping in Montgomery County will ELECT directors of the Lone Star Groundwater Conservation District for the first time in November.
If people vote for candidates who advocate use of “cheaper” groundwater in the short term, they will also be voting for subsidence and policies that limit long-term growth. Without question, they will be betting their future on a rapidly depleting water source.
If that’s the will of the people, so be it. I just hope they don’t set a precedent that residents in neighboring counties follow. If so, we could all be sunk.
Red contours show subsidence in the last century. Blue contours show how much subsidence has increased in the first sixteen years of this century. Note the widening gap between red and blue at the top of the frame. It shows that subsidence in Montgomery and northern Harris Counties is increasing at an increasing rate. Parts of Harris County have subsided 10 feet! Source: Harris-Galveston Subsidence District.
Posted 9/14/2018 by Bob Rehak
382 Days since Hurricane Harvey
Note: Because this is such an important issue, I have created a new tab titled Subsidence on the Reports page.
00adminadmin2018-09-15 01:27:322018-09-15 11:15:56Another Storm Brewing: The Groundwater Debate and How It Relates to Flood Risk
This afternoon, the U.S. Army Corps of Engineers issued a two-sentence press release about the start of their emergency West Fork dredging project.
Two-Sentence Dredging Update
It simply said, “USACE contractors are prepared to begin moving the first dredge on Sunday afternoon with operations possibly beginning Monday. If weather conditions pose threats to operational safety, dredging along West Lake Houston Parkway will begin when conditions improve.”
Tropical Development Complicates Dredging
Safety issues related to a potential tropical rain event now have the Corps concerned about safety. Note that orange X in the oval below that’s aimed toward the Texas coast..
Low Pressure System in Gulf has 50% Chance of Formation for up to 5 days.
Latest Tropical Updates for Gulf
As of 3PM Thursday, the National Hurricane Center (NHC) said about it, “A weak low pressure center has formed a couple of hundred miles east-southeast of Brownsville, Texas. In addition, showers and thunderstorms in association with this system have become more numerous today. While upper-level winds are generally conducive for development of a tropical depression, the system only has about a day before it reaches the western Gulf coast. An Air Force Reserve Hurricane Hunter aircraft is currently en route to investigate the low.”
Regardless of development, heavy rainfall and gusty winds are expected across portions of northeastern Mexico and Texas on Friday and Saturday.
Monitor the progress of this system, and refer to local weather forecasts.
Lakes Already Lowered in Advance of Rainmaker
In preparation for the storm, Lake Conroe has already been lowered to its seasonally adjusted target of 199 mean feet above sea level.
Level of Lake Houston has also been lowered.
Lowering the two lakes gives us an additional buffer against flooding, but still, a rain-swollen river is no place for a 270 ton dredge tethered to hundreds of thousands of pounds of dredging pipe.
Updates on Ben’s Branch
Let’s just pray we don’t get so much rain that the ditches back up. When last we talked about ditches, the City had mistakenly sent the wrong easements to the county, so that the county could maintain Kingwood ditches. The City finally regrouped on the 11th. On the 12th, the City contacted Kingwood Association Management’s Ethel McCormick. McCormick is working to put the City together with the Bear Branch Trail Association and the Kings Crossing Association re: easements. More news on that when there’s news to share.
County Begins Surveying Ben’s Branch
In the meantime, Harris County is wasting no time. In expectation of the easements, they were already out surveying the ditches to determine how much silt and debris needed to be removed.
Harris County Surveying Truck near Ben’s Branch
Just east of West Lake Houston Parkway, a Harris County Flood Control Surveying Crew was seen this week trying to calculate the debris that needs to be removed from Ben’s Branch.=
Harris County Surveying Crew in Ben’s Branch just west of West Lake Houston Parkway. Crews are trying to estimate how much silt needs to be removed to restore the carrying capacity of the ditch. Note the surveyor in the far background on the island.
Blockages like those above created during Harvey contributed to flooding in Town Center and Kings Crossing. Note the proximity of Ben’s Branch to the back of the old HEB shopping center on the northwest corner of Kingwood Drive and West Lake Houston Parkway.
I asked Matt Zeve, Director of Operations for Harris County Flood Control whether they planned to use the silt from Ben’s Branch to increase the height of the levies or whether they planned to remove it. The answer: remove it.
Work on Ben’s Branch cannot begin too soon. Uncertainty concerning this important waterway restrains the retail recovery throughout the central part of Kingwood.
The old HEB store still has not been leased to a new tenant.
Without a lead tenant in the old HEB space, leasing the smaller stores in this center is a long shot, especially when the flood risk has not yet been reduced.
Many prospective tenants are waiting on signs from the City and County that flood remediation is about to begin. The 20,000 sf Kelsey Seybold Clinic has also been vacant since Harvey and has a For Lease sign in the window.
Other high visibility retail and rental spaces also remain vacant, i.e., the Chase Bank on Kingwood Drive and West Lake Houston Parkway, the new Memorial Hermann Health Care Facility, several apartment communities, and much of King’s Harbor.
Plea for Progress to Government
It will take more than deals to lure retailers and residents back to these locations; it will also take genuine progress in flood remediation – much faster progress than we have seen in the year since Harvey. People need confidence that their investments in buildout, inventory, and equipment will not be taken in the next flood. We spent a year talking about remediation; let’s get started.
Posted 9/13/2018 by Bob Rehak
380 Days since Hurricane Harvey
00adminadmin2018-09-13 17:03:062018-09-13 17:03:06Dredging, Tropic, Lake, Ditch, and Retail Updates: Sometimes Progress is Measured in Inches
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
Another Storm Brewing: The Groundwater Debate and How It Relates to Flood Risk
Groundwater relates to flooding? Yes. Here’s how. And here’s why you should care, especially now.
In November, Montgomery County voters will elect board members to the Lone Star Groundwater Conservation District who may advocate using more groundwater, a move that some believe could give residents cheaper water in the short run, but which could also cause subsidence, contribute to flooding, create shortages, raise costs and limit growth in the long run.
Unequal Groundwater Withdrawals, Unequal Subsidence
Subsidence is scientifically well documented and understood. Removing groundwater from clay causes the clay to compress. When that happens, you sink. And once clay is compressed, it stays compressed forever – even when rehydrated.
Yet some Montgomery County voters are advocating removing more groundwater because, at this moment, it’s cheaper than surface water. They are betting their future and their neighbors’ futures on it.
Subsidence can contribute to flooding because not everybody subsides equally. While Kingwood only subsided two feet in the last century, one part of Baytown subsided so much that it became uninhabitable in about half that time.
In 1944, the area that would become Brownwood in Baytown was starting to show signs of development.
By 1978, Brownwood was well developed…and sinking fast.
Today, the area floods so much that it is uninhabitable. All the homes are gone. Brownwood has been turned into a park.
The “Pump-Now, Let-Somebody-Else-Pay-Later” Mentality
Subsidence generally happens so slowly that some people claim it’s not a problem. Especially those on higher ground. They want to continue to pump water from their wells because they perceive it to be cheaper than surface water. It can be…at least in the short run..until wells run low or dry. Then pumping costs increase…often along with salinity…and the people who depend on the well are out of water and out of luck.
Gulf Coast Aquifers: Source Harris-Galveston Subsidence District. Much of the water in Montgomery County used for human consumption is pumped from the Jasper aquifer.
Depleting at More Than 500X the Recharge Rate
Still, some people say, “I’ll worry about that when it happens.” Problem is:
More Expensive in Long Run
Now consider this. As pressure in an aquifer decreases, the cost of bringing water to the surface increases dramatically, sometimes to the point where recovery is no longer economical, i.e., competitive with surface water. It’s much like the oil industry. As a rule of thumb, half the oil in reservoirs is left in the ground because it’s too expensive to recover.
For all these reasons, most counties in the region are trying to switch people to surface water. Their groundwater withdrawals have either declined or stayed the same.
Counties surrounding Montgomery have either decreased groundwater pumping or kept it constant.
Meanwhile, Montgomery County’s groundwater withdrawals have soared.
Montgomery County groundwater pumping, however, has generally increased in the last three decades.
A report by LBG Guyton Associates to the Lone Star Groundwater Conservation District showed that the largest increase in pumping since 2000 has occurred in Montgomery County. Pumping in surrounding counties has generally decreased since 2000.
Montgomery County Growth
The surge in Montgomery County groundwater usage is largely because Montgomery County has grown so quickly. With the exception of Fort Bend County, Montgomery County is growing faster than any county in the region on a percentage basis.
Houston Region growth last year by county. In percentage terms, Montgomery County trailed only Fort Bend County.
So Why Worry NOW?
Water resources take so long to develop that they need to be planned 50 years into the future. The Houston region’s population tripled in the last 50 years.
If Montgomery County expects to grow that fast in the next 50, where will the water come from to support that growth? Especially if voters undermine the financial viability of the half-billion dollar surface-water treatment plant – that they just built – by shifting to groundwater!
Proponents of unlimited groundwater pumping in Montgomery County will ELECT directors of the Lone Star Groundwater Conservation District for the first time in November.
If that’s the will of the people, so be it. I just hope they don’t set a precedent that residents in neighboring counties follow. If so, we could all be sunk.
Red contours show subsidence in the last century. Blue contours show how much subsidence has increased in the first sixteen years of this century. Note the widening gap between red and blue at the top of the frame. It shows that subsidence in Montgomery and northern Harris Counties is increasing at an increasing rate. Parts of Harris County have subsided 10 feet! Source: Harris-Galveston Subsidence District.
Posted 9/14/2018 by Bob Rehak
382 Days since Hurricane Harvey
Note: Because this is such an important issue, I have created a new tab titled Subsidence on the Reports page.
Dredging, Tropic, Lake, Ditch, and Retail Updates: Sometimes Progress is Measured in Inches
Updates on several subjects.
This afternoon, the U.S. Army Corps of Engineers issued a two-sentence press release about the start of their emergency West Fork dredging project.
Two-Sentence Dredging Update
It simply said, “USACE contractors are prepared to begin moving the first dredge on Sunday afternoon with operations possibly beginning Monday. If weather conditions pose threats to operational safety, dredging along West Lake Houston Parkway will begin when conditions improve.”
Tropical Development Complicates Dredging
Safety issues related to a potential tropical rain event now have the Corps concerned about safety. Note that orange X in the oval below that’s aimed toward the Texas coast..
Low Pressure System in Gulf has 50% Chance of Formation for up to 5 days.
Latest Tropical Updates for Gulf
As of 3PM Thursday, the National Hurricane Center (NHC) said about it, “A weak low pressure center has formed a couple of hundred miles east-southeast of Brownsville, Texas. In addition, showers and thunderstorms in association with this system have become more numerous today. While upper-level winds are generally conducive for development of a tropical depression, the system only has about a day before it reaches the western Gulf coast. An Air Force Reserve Hurricane Hunter aircraft is currently en route to investigate the low.”
Monitor the progress of this system, and refer to local weather forecasts.
Lakes Already Lowered in Advance of Rainmaker
In preparation for the storm, Lake Conroe has already been lowered to its seasonally adjusted target of 199 mean feet above sea level.
Level of Lake Houston has also been lowered.
Lowering the two lakes gives us an additional buffer against flooding, but still, a rain-swollen river is no place for a 270 ton dredge tethered to hundreds of thousands of pounds of dredging pipe.
Updates on Ben’s Branch
Let’s just pray we don’t get so much rain that the ditches back up. When last we talked about ditches, the City had mistakenly sent the wrong easements to the county, so that the county could maintain Kingwood ditches. The City finally regrouped on the 11th. On the 12th, the City contacted Kingwood Association Management’s Ethel McCormick. McCormick is working to put the City together with the Bear Branch Trail Association and the Kings Crossing Association re: easements. More news on that when there’s news to share.
County Begins Surveying Ben’s Branch
In the meantime, Harris County is wasting no time. In expectation of the easements, they were already out surveying the ditches to determine how much silt and debris needed to be removed.
Harris County Surveying Truck near Ben’s Branch
Just east of West Lake Houston Parkway, a Harris County Flood Control Surveying Crew was seen this week trying to calculate the debris that needs to be removed from Ben’s Branch.=
Harris County Surveying Crew in Ben’s Branch just west of West Lake Houston Parkway. Crews are trying to estimate how much silt needs to be removed to restore the carrying capacity of the ditch. Note the surveyor in the far background on the island.
I asked Matt Zeve, Director of Operations for Harris County Flood Control whether they planned to use the silt from Ben’s Branch to increase the height of the levies or whether they planned to remove it. The answer: remove it.
Work on Ben’s Branch cannot begin too soon. Uncertainty concerning this important waterway restrains the retail recovery throughout the central part of Kingwood.
The old HEB store still has not been leased to a new tenant.
Without a lead tenant in the old HEB space, leasing the smaller stores in this center is a long shot, especially when the flood risk has not yet been reduced.
Many prospective tenants are waiting on signs from the City and County that flood remediation is about to begin. The 20,000 sf Kelsey Seybold Clinic has also been vacant since Harvey and has a For Lease sign in the window.
Other high visibility retail and rental spaces also remain vacant, i.e., the Chase Bank on Kingwood Drive and West Lake Houston Parkway, the new Memorial Hermann Health Care Facility, several apartment communities, and much of King’s Harbor.
Plea for Progress to Government
It will take more than deals to lure retailers and residents back to these locations; it will also take genuine progress in flood remediation – much faster progress than we have seen in the year since Harvey. People need confidence that their investments in buildout, inventory, and equipment will not be taken in the next flood. We spent a year talking about remediation; let’s get started.
Posted 9/13/2018 by Bob Rehak
380 Days since Hurricane Harvey
Flooding and Floodplains in the Houston Area: Past, Present, and Future
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
In Part 1, Dupré focuses on the basics of flooding, flood plains and measurement. He begins by explaining:
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.
How and Why Floodplains Change Over Time
In Part 2, Dupré goes into greater detail about how floodplains change over time. The four main reasons include:
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.
Related Reading
The points Dr. Dupré makes support the conclusions drawn in a report by the Bayou City Initiative titled “Houston A Year after Harvey: Where We Are and Where We Need to Be,” especially the section on the need to revise outdated flood maps.
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