What are upstream watersheds’ relative contributions to Lake Houston Area flooding? During a flood, where does all the water come from? Of course, it depends on how much rain falls where and when, and how long it takes to concentrate downstream. Rainfall is rarely uniform across an entire region.
But still, when considering hundreds of events over time, variations tend to average out. So, considering a hypothetical scenario that assumes a uniform distribution of rain can yield useful insights for planning flood-mitigation and conservation efforts.
Revisiting the January Flood
During late January 2024, the north and west Houston areas experienced widespread flooding. Even though most of the rain didn’t fall around Lake Houston, excess stormwater worked its way downstream over several days and wound up flooding the area. This caused widespread confusion.
During the event, many people put all the blame for downstream flooding on the 19,500 cubic-foot-per-second release from Lake Conroe. However, river gages showed upstream flooding in other watersheds as well. They included Lake Creek, Cypress Creek, Spring Creek and the West Fork below Lake Conroe.
Rainfall is rarely uniformly distributed across a region as large as Houston. But it’s not just how much falls where. The size of a watershed and how it converges with others also affect downstream flooding.
That prompted an interesting question that I asked Jeff Lindner, Harris County’s meteorologist.
Given uniform rainfall throughout the region, how much would each upstream watershed contribute to Lake Houston Area flooding during a 100-year rain?
Lindner worked with engineers at the San Jacinto River Authority (SJRA) to calculate the volumes below. Eleven different watersheds from seven counties feed into Lake Houston.
The table below summarizes their size in square miles, calculates the acre-feet of runoff in a 100-year event, and then determines each watershed’s percentage of the total passing through Lake Houston.
Upstream watersheds’ relative contributions to Lake Houston Area flooding.Assumes uniform distribution of rainfall throughout region.
The map below shows the location of each of the eleven contributing watersheds with the percentages above superimposed.
Map courtesy of SJRA. Percentages courtesy of Jeff Lindner and SJRA. Only watersheds draining through Lake Houston were considered for this exercise.
Observations
What can we conclude from these numbers? If rainfall is evenly distributed across the region:
Lake Conroe releases aren’t the only thing contributing to Lake Houston Area floods. SJRA controls only 13% of the runoff. That’s because the Lake Conroe Dam is the only dam in the eleven watersheds draining into Lake Houston.
Watersheds vary radically in their size – 7.5X. So we need to be careful when generalizing about the contribution of different areas to flooding.
37% of the runoff coming into Lake Houston comes via the East Fork San Jacinto and its sub-watersheds.
63% comes under the I-69 bridge into the West Fork between Humble and Kingwood.
35% of the region’s drainage comes down the West Fork and passes through an area between I-45 and I-69 with 20 square miles of sand mines.
In total, almost 2 million acre feet will drain into Lake Houston during a 100-year rain.
The implications of that last fact for flood mitigation are enormous.
One hydrologist I consulted for this post said, “I don’t know the exact amount of detention storage needed to significantly reduce flooding risks in Kingwood, but it will probably be at least another Lake Conroe’s worth of storage. That may help drive home the challenge facing HCFCD, SJRA, COH, and Montgomery County.”
And the money to accomplish that will likely take State and Federal backing.
Reviewing watersheds’ relative contributions to Lake Houston Area flooding may also be helpful in:
Visualizing where water comes from in a flood.
Determining the optimal locations for potential, regional, stormwater-detention basins/dams, such as those proposed along tributaries of Spring Creek.
Focusing conservation efforts, such as the Bayou Land Conservancy’s recent dedication of a preserve along Lake Creek.
Controlling sedimentation, i.e., planning for the retirement of West Fork sand mines, which have become leaky sieves.
As always, nothing clears brain fog faster than clean data, well summarized and presented. My thanks to Jeff Lindner and the SJRA for their help with this post.
Posted by Bob Rehak on 3/10/24
2385 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2024/03/image002.png?fit=330%2C326&ssl=1326330adminadmin2024-03-10 14:53:302026-04-05 22:56:46Upstream Watersheds’ Relative Contributions to Lake Houston Area Flooding
Today, Entergy missed yet another deadline in a long series of deadlines to move its power lines to make room for Northpark Drive expansion.
On February 6, the City of Houston sent a letter to Entergy, demanding that the company move its power lines out of the City’s right of way within 30 days. That would have given them until March 8 to comply. But as of today, March 9, 2024, not one of the poles had moved.
The City’s agent, Lake Houston Redevelopment Authority/TIRZ 10, first asked Entergy to move the poles four years ago. This is just another in a long line of disappointments that have delayed the Northpark Drive Expansion Project – driving up taxpayer costs, increasing flood risk, and snarling traffic.
Last month, Entergy refused to provide ReduceFlooding.com with a copy of its response to the City. And today, Entergy did not return a phone call explaining why the company ignored the City deadline.
Before/After Photos
Here’s how the north-side/west-bound expansion area near the UP tracks looked before the City sent its demand letter.
Photo taken Jan. 13, 2024, before City sent letter to Entergy.
And here’s how the same area looked this morning. Not one pole has moved as a result of the City’s February 6 letter.
Photo taken around noon on March 9, more than 30 days after letter was sent. Nothing has moved.Reverse angle. Looking E along Northpark at endless backups and poles still in original locations. Also taken March 9th.
As I took these photos Saturday near noon, traffic was backed up more than a mile!
Clash over Cash
In the past, Entergy asked for compensation to move its poles. But according to an LHRA spokesperson, compensation is not allowable under Texas law because the poles were in a City right of way and not covered by an easement. Thus, any payment would have constituted a “gift of public funds,” which the Texas Constitution prohibits.
Entergy was, however, legally entitled to compensation for moving buried wires in an easement near the Exxon station at US59. Entergy had agreed to move them for $711,000 near Christmas last year. However…
Entergy still has not moved buried wires or a transformer near the Exxon station at US59.
…within days after the disagreement about payment for relocating the poles, Entergy’s asking price to move the underground wires mysteriously increased by half a million dollars. Simultaneously, their cost estimate went from line item to lump sum – without itemization. Since then, the asking price has increased another $200,000 without explanation.
Previous Communications with Entergy
City of Houston held Utility Coordination Meetings with Entergy on 10/8/20, 12/10/20, 01/14/21, 2/11/21, 3/11/21, 2/10/22, 3/10/22, and 4/14/22.
In addition, the City also emailed Entergy’s Utility Relocation consultant on 12/07/20, 06/21/21, 06/30/22, 07/22/22, 08/19/22, 09/20/22, 10/21/22, 01/11/23, 01/24/23, 03/03/23, 05/17/23, 07/19/23, 08/23/23, 10/16/23, 10/26/23, 12/01/23, and 12/13/24, 01/16/24.
I don’t care to speculate on the motives for Entergy’s lethargy. However, I’m pretty certain that if this goes to court, the entire project could be delayed years.
You can draw your own conclusions and point fingers where you will.
If there was ever any doubt, Entergy now knows that one of the main goals of Northpark Expansion is to provide an all-weather evacuation route for 78,000 Kingwood and Porter residents. Personally, I hate feeling like a pawn in Entergy’s game.
Posted by Bob Rehak on 3/9/24
2384 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/2024/03/20240309-RJR_3276-e1710029012230.jpg?fit=733%2C458&ssl=1458733adminadmin2024-03-09 18:52:132024-03-09 19:01:35Entergy Ignores City Deadline to Move Northpark Power Lines
On 3/7/24, TxDOT, the Lake Houston Redevelopment Authority/TIRZ10 and the City of Houston hosted an open house at the Kingwood Community Center to share detailed project plans at a Northpark Phase II Meeting. The informal “come-and-go-when-you want” style of the meeting gave authorities a chance to mingle with residents and solicit their feedback on plans.
Two hundred and forty-six people attended the Phase II meeting in person or virtually.
Objectives of Project
In addition to reducing traffic congestion, one of the main goals is to elevate Northpark Drive above the 100-year floodplain to create an all-weather evacuation route for area residents. Other goals include preparing for anticipated growth and improving pedestrian/bicycle safety.
Different Lanes for Different Pains
As with Phase I, roads will be elevated. Lanes will be both added and widened. Eleven-foot-wide lanes will expand to 12 feet. And 10-foot-wide sidewalks will be added, enabling bicyclists and pedestrians to pass each other easily.
Proposed improvements to Northpark Drive extend from 750 feet east of Russell Palmer Road to 800 feet east of Woodland Hills Drive, in Harris and Montgomery Counties. The project would include the reconstruction and widening of approximately one mile of Northpark Drive from a four-lane to a six-lane roadway.
TXDoT broke Phase II into three sections based on current lane configurations and traffic conditions.
Section A starts about halfway between Russell-Palmer and the Kingwood Diversion Ditch and goes up to the Ditch. “A” also includes the Woodland Hills/Northpark Drive Intersection.
Section B goes from the Ditch to the start of the Northpark Place Commercial Association.
Section C includes businesses inside Kingwood almost to Woodland Hills, where Section A restarts.
The three lanes would include two 12-foot-wide main lanes in each direction; left and right turning lanes; and 1-foot-wide outside/inside shoulders.
The area where the grassy median is today would be repurposed to use as turning lanes or additional travel lanes.
TxDOT
The wooden pylon sign that says “Kingwood” will go. However, according to Dee Price, KSA President, the serpentine wall that heralds “The Livable Forest” would remain after construction.
Reconstruction will also include new signals at the Woodland Hills Drive and Hidden Pines Drive intersections.
To reduce flooding, the project also includes new drainage features, such as open ditches, curb-and-gutter, and one stormwater-detention basin in a location yet to be determined.
Business owners especially need to understand how a change in traffic patterns could affect their businesses.
Construction is still several years away. The most likely start date: 2027. Between now and then, project managers will focus on environmental surveys, detailed design, and right-of-way acquisition.
Starting on March 11, one lane will close on Russell Palmer during installation of the temporary signals.
The water line to Parkwood Baptist Church which held up construction has now been repaired. A crew will soon splice in the missing piece of culvert with a concrete sleeve to tie adjacent sections together.
Upstream Watersheds’ Relative Contributions to Lake Houston Area Flooding
What are upstream watersheds’ relative contributions to Lake Houston Area flooding? During a flood, where does all the water come from? Of course, it depends on how much rain falls where and when, and how long it takes to concentrate downstream. Rainfall is rarely uniform across an entire region.
But still, when considering hundreds of events over time, variations tend to average out. So, considering a hypothetical scenario that assumes a uniform distribution of rain can yield useful insights for planning flood-mitigation and conservation efforts.
Revisiting the January Flood
During late January 2024, the north and west Houston areas experienced widespread flooding. Even though most of the rain didn’t fall around Lake Houston, excess stormwater worked its way downstream over several days and wound up flooding the area. This caused widespread confusion.
During the event, many people put all the blame for downstream flooding on the 19,500 cubic-foot-per-second release from Lake Conroe. However, river gages showed upstream flooding in other watersheds as well. They included Lake Creek, Cypress Creek, Spring Creek and the West Fork below Lake Conroe.
Rainfall is rarely uniformly distributed across a region as large as Houston. But it’s not just how much falls where. The size of a watershed and how it converges with others also affect downstream flooding.
Hypothetical Uniformly Distributed 100-Year Rainfall
That prompted an interesting question that I asked Jeff Lindner, Harris County’s meteorologist.
Lindner worked with engineers at the San Jacinto River Authority (SJRA) to calculate the volumes below. Eleven different watersheds from seven counties feed into Lake Houston.
The table below summarizes their size in square miles, calculates the acre-feet of runoff in a 100-year event, and then determines each watershed’s percentage of the total passing through Lake Houston.
The map below shows the location of each of the eleven contributing watersheds with the percentages above superimposed.
Observations
What can we conclude from these numbers? If rainfall is evenly distributed across the region:
The implications of that last fact for flood mitigation are enormous.
One hydrologist I consulted for this post said, “I don’t know the exact amount of detention storage needed to significantly reduce flooding risks in Kingwood, but it will probably be at least another Lake Conroe’s worth of storage. That may help drive home the challenge facing HCFCD, SJRA, COH, and Montgomery County.”
And the money to accomplish that will likely take State and Federal backing.
Reviewing watersheds’ relative contributions to Lake Houston Area flooding may also be helpful in:
As always, nothing clears brain fog faster than clean data, well summarized and presented. My thanks to Jeff Lindner and the SJRA for their help with this post.
Posted by Bob Rehak on 3/10/24
2385 Days since Hurricane Harvey
Entergy Ignores City Deadline to Move Northpark Power Lines
Today, Entergy missed yet another deadline in a long series of deadlines to move its power lines to make room for Northpark Drive expansion.
On February 6, the City of Houston sent a letter to Entergy, demanding that the company move its power lines out of the City’s right of way within 30 days. That would have given them until March 8 to comply. But as of today, March 9, 2024, not one of the poles had moved.
The City’s agent, Lake Houston Redevelopment Authority/TIRZ 10, first asked Entergy to move the poles four years ago. This is just another in a long line of disappointments that have delayed the Northpark Drive Expansion Project – driving up taxpayer costs, increasing flood risk, and snarling traffic.
Last month, Entergy refused to provide ReduceFlooding.com with a copy of its response to the City. And today, Entergy did not return a phone call explaining why the company ignored the City deadline.
Before/After Photos
Here’s how the north-side/west-bound expansion area near the UP tracks looked before the City sent its demand letter.
And here’s how the same area looked this morning. Not one pole has moved as a result of the City’s February 6 letter.
As I took these photos Saturday near noon, traffic was backed up more than a mile!
Clash over Cash
In the past, Entergy asked for compensation to move its poles. But according to an LHRA spokesperson, compensation is not allowable under Texas law because the poles were in a City right of way and not covered by an easement. Thus, any payment would have constituted a “gift of public funds,” which the Texas Constitution prohibits.
Entergy was, however, legally entitled to compensation for moving buried wires in an easement near the Exxon station at US59. Entergy had agreed to move them for $711,000 near Christmas last year. However…
…within days after the disagreement about payment for relocating the poles, Entergy’s asking price to move the underground wires mysteriously increased by half a million dollars. Simultaneously, their cost estimate went from line item to lump sum – without itemization. Since then, the asking price has increased another $200,000 without explanation.
Previous Communications with Entergy
City of Houston held Utility Coordination Meetings with Entergy on 10/8/20, 12/10/20, 01/14/21, 2/11/21, 3/11/21, 2/10/22, 3/10/22, and 4/14/22.
In addition, the City also emailed Entergy’s Utility Relocation consultant on 12/07/20, 06/21/21, 06/30/22, 07/22/22, 08/19/22, 09/20/22, 10/21/22, 01/11/23, 01/24/23, 03/03/23, 05/17/23, 07/19/23, 08/23/23, 10/16/23, 10/26/23, 12/01/23, and 12/13/24, 01/16/24.
I don’t care to speculate on the motives for Entergy’s lethargy. However, I’m pretty certain that if this goes to court, the entire project could be delayed years.
You can draw your own conclusions and point fingers where you will.
If there was ever any doubt, Entergy now knows that one of the main goals of Northpark Expansion is to provide an all-weather evacuation route for 78,000 Kingwood and Porter residents. Personally, I hate feeling like a pawn in Entergy’s game.
Posted by Bob Rehak on 3/9/24
2384 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.
TxDOT, LHRA Engage Kingwood at Northpark Phase II Meeting
On 3/7/24, TxDOT, the Lake Houston Redevelopment Authority/TIRZ10 and the City of Houston hosted an open house at the Kingwood Community Center to share detailed project plans at a Northpark Phase II Meeting. The informal “come-and-go-when-you want” style of the meeting gave authorities a chance to mingle with residents and solicit their feedback on plans.
Objectives of Project
In addition to reducing traffic congestion, one of the main goals is to elevate Northpark Drive above the 100-year floodplain to create an all-weather evacuation route for area residents. Other goals include preparing for anticipated growth and improving pedestrian/bicycle safety.
Different Lanes for Different Pains
As with Phase I, roads will be elevated. Lanes will be both added and widened. Eleven-foot-wide lanes will expand to 12 feet. And 10-foot-wide sidewalks will be added, enabling bicyclists and pedestrians to pass each other easily.
Proposed improvements to Northpark Drive extend from 750 feet east of Russell Palmer Road to 800 feet east of Woodland Hills Drive, in Harris and Montgomery Counties. The project would include the reconstruction and widening of approximately one mile of Northpark Drive from a four-lane to a six-lane roadway.
TXDoT broke Phase II into three sections based on current lane configurations and traffic conditions.
The three lanes would include two 12-foot-wide main lanes in each direction; left and right turning lanes; and 1-foot-wide outside/inside shoulders.
The wooden pylon sign that says “Kingwood” will go. However, according to Dee Price, KSA President, the serpentine wall that heralds “The Livable Forest” would remain after construction.
Reconstruction will also include new signals at the Woodland Hills Drive and Hidden Pines Drive intersections.
To reduce flooding, the project also includes new drainage features, such as open ditches, curb-and-gutter, and one stormwater-detention basin in a location yet to be determined.
See additional details about what will happen in each section in this presentation or these meeting handouts.
Still Time to Provide Public Comment
If you missed the meeting last night, you can still provide public input. Review the materials above and send your comments via:
If you own a business along Northpark, don’t miss this preliminary schematic construction diagram that shows rights of way and more plan details.
Business owners especially need to understand how a change in traffic patterns could affect their businesses.
Construction is still several years away. The most likely start date: 2027. Between now and then, project managers will focus on environmental surveys, detailed design, and right-of-way acquisition.
Upcoming Schedule
LHRA has also provided a three-week look-ahead schedule to show you what will happen when.
Two important items on it include:
For More Information
For more information about the project including Phase I, visit the project pages of the LHRA/Tirz 10 website. Or see these posts on ReduceFlooding:
Posted by Bob Rehak on 3/8/24
2383 Days since Hurricane Harvey