Below is a quick digest of six flood-related stories affecting the Lake Houston Area.
Dredging is a Slow Go
Mechanical dredgers are slowly working their way through the channel south of Royal Shores. It connects the East and West Forks of the San Jacinto. Without dredging, the dredging equipment itself would not be able to make it through the channel.
However, the pace of the dredging is painfully slow. You can see the progress by comparing the two pictures below. I took them 22 days apart.
Taken on July 11, 2021Taken on August 2, 2021. Google Earth shows they went a little more than 600 feet in a little more than three weeks.
At about 200 feet per week with about 2,000 more feet to go, they should reach the East Fork in about another ten weeks.
Several boaters have commented on how the dredges can wait hours for a pontoon to ferry dirt back to the placement site. Their net takeaway: very inefficient. During a July 8 meeting at the Kingwood Community Center, Stephen Costello called this method of dredging “unsustainable.” He’s sooooo right. We will run out of luck long before we run out of places to dredge.
Mechanical dredging (shown in the photos above) is far slower and less efficient than hydraulic. Great Lakes hydraulic dredges removed 500,000 cubic yards of sediment from the mouth bar area in just two months – July and August of 2019. DRC’s mechanical dredges removed another 600,000+ cubic yards in the 19 months between January 2020 and July 2021.
Interestingly, Google Earth shows that when the dredgers reach the East Fork, they will be closer to the Triple PG Sand Mine in Porter than the current placement area south of River Grove Park. The Triple PG mine will also be less than half the distance of a mine that the Army Corps previously pumped spoils to from the mouth bar– the Eagle Sorters Mine on the West Fork.
Hmmmm. Triple PG. A placement area for East Fork spoils? A return to hydraulic dredging? Interesting thoughts.
Seasonal Lowering of Lake Conroe
Seasonal lowering of Lake Conroe has started as planned. SJRA is releasing 75 cubic feet per second, according to their dashboard.
Seasonal release is shown as a City of Houston (COH) Diversion.
When the lowering started on August 2, a day late, the lake was at 200.87. So releasing 75 CFS has brought the lake down .19 feet, a little more than 2 inches. Barring large rainfalls, this rate should reach the objective of 200 feet by September 1.
The National Hurricane Center shows two areas of concern in the Atlantic as of 2PM, Friday August 6th.
A few hundred miles south of the Cabo Verde Islands, a tropical wave (orange area) and a broad area of low pressure could turn into a tropical depression by late this weekend or early next week. Formation chance through 5 days…medium…60 percent.
Another tropical wave approaching the Lesser Antilles is a lower threat. NHC predicts development, if any, of this system will be slow and occur early next week. Formation chance through 5 days…low…20 percent.
NOAA Issues Mid-Season Hurricane Outlook
Another forecast released two days ago by NOAA says that atmospheric conditions are still conducive for an above-average hurricane season. See their predictions in the right hand column below. These numbers include the five named storms so far this season.
Attorney General Lawsuit Against Triple PG Mine Still Active
Craig Pritzlaff of the TCEQ assures me that despite visible lack of progress in the Attorney General’s lawsuit against the Triple PG mine for illegal discharges, the AG has not dropped the case. “Indeed, very few, if any, cases referred to the AG for civil prosecution are ever dropped,” he says. “Litigation, particularly environmental litigation, is a complicated and lengthy process. That process was further complicated by the COVID-19 pandemic, which halted court dockets across the State throughout 2020 and into 2021.”
Condos 250 Feet from 250,000 CFS
A Chinese developer is building yet more condos even closer to the West Fork in the Kings Harbor neighborhood.
See new construction bottom center. Lai finished the units at the right earlier this year. The nearest unit above will be about 250 feet from the San Jacinto West Fork.
During Harvey, more than 250,000 cubic feet per second came through this area. It flooded homes and businesses more than 10,000 feet from the river.
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/2021/08/20210802-DJI_0286.jpg?fit=1200%2C799&ssl=17991200adminadmin2021-08-06 16:46:402021-08-07 19:38:36Digest: Updates on Six Lake Houston Area Flood-Related Stories
Did you know that one-third of the area in Harris County now has impervious cover? That Montgomery County had a 57.12% net increase of impervious surface area between 2001 and 2019? Or that 10% of land cover in the Lower 48 states changed during that same period? I discovered these and a multitude of other fascinating facts in a recently updated United States Geological Survey (USGS) website dedicated to monitoring changes in land cover, for example, from forested to developed.
When you live in an area for a long time, it’s easy to forget what happened two decades ago. And when you move to a new area, you just accept what is and don’t worry about what was.
But USGS gives you a quick and easy way to see and quantify changes in land use down to the county level. It’s useful in telling you where flood threats could develop over time and how fast they are developing.
About the USGS National Land Cover Database
USGS recently released updated land cover maps for the lower 48 United States. They show how the country’s landscapes have changed over an 18 year period in two- to three-year increments. It’s called the United States National Land Cover Database (NLCD). And it’s the fastest way to see how your county is changing.
Updates include 2001, 2004, 2006, 2008, 2011, 2013, 2016, and 2019.
Developed using Landsat imagery, NLCD classifies land cover into 16 groups with 30-meter resolution. The data includes both land-cover and urban imperviousness changes.
USGS claims 91 percent accuracy for the NLCD data. For more detail about how NLCD was developed see: Changes to the National Land Cover Database. More than nine billion pixels make up the land-cover dataset.
The USGS National Land Cover Database’s suite of GIS mapping products even includes a layer that defines the intensity of impervious surfaces across the United States. This information is used in runoff modeling, urban heat estimation, and a variety of other applications.
Mapping Land Cover Change in U.S. Over Time
Users can visualize land cover changes in the United States by accessing the the Enhanced Visualization and Analysis (EVA) tool. The online mapping tool was developed by USGS in partnership with the National Oceanic and Atmospheric Administration.
The tool allows users to select any county in the Lower-48 United States and generate a custom report on land cover change, developed areas, cropland change, and other factors.
Only one caution: the USGS site does not work with Apple’s Safari Browser. Mac users can use Firefox without problems, however. I have not tested other Mac browsers.
Almost one fifth of the land cover changed type (18.23%).
Developed portions of the county increased from 54.42% to 65.85% of the total acreage, a 20.99% percent net increase of developed area.
Forested parts of the county went from 10.64% to 6.29%, a percent net decrease of 40.92%.
The percent covered in wetlands went down from 8.28% to 7.02%, another percent net decrease of 15.24%.
The percentage of impervious surface increased from about a quarter to a third (26.28% to 33.39%), a percent net increase of 27.05%.
Screen showing development changes in Harris County with corresponding percentages of impervious cover. Green dots represent changes in land use.Clicking on icons in left column brings up different types of information.
MoCo Changes at a Glance
During the same period, in Montgomery County:
Even more land cover changed type (18.99%).
Developed portions of the county increased from 21.1% of the land area to 28.27%, a 33.97% net increase.
Impervious cover increased from 5.78% off the land area to 9.08%, a 57.12% increase.
Forested land decreased from 42.98% of the county to 38.96%, a 9.16% net decrease.
Wetlands decreased from 12.17% of the county to 11.35%, a 6.74% net decrease.
Agricultural land decreased from 12.28% to 10.31% of the county, a 16.04% net decrease.
Red areas represent areas in Montgomery County that changed land-cover type between 2001 and 2019.
Another screen showing areas in Montgomery County developed between 2001 and 2019.
Key Lesson
This database and GIS mapping system dramatize how quickly the region is growing and land use is changing.
Flood mitigation is or should be a two-pronged effort. We must fix problems that already exist downstream while hopefully preventing future problems from developing upstream. It’s not a just question of one county spending money to help prevent problems in another. It’s about surrounding counties protecting themselves. The outward expansion is relentless. People at the edge today will be downstream from someone else tomorrow.
There’s little anyone can do to change the FACT of development. But we can change the NATURE of development. If all new developments retained their own rain, no one would ever be doomed to the flood-mitigation treadmill of keeping up with ever-increasing amounts of upstream runoff.
Montgomery County already has a serious flooding problem of its own. Thousands of people flooded there during Harvey and Imelda.
Posted by Bob Rehak on 8/5/2021based on USGS information
1437 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/2021/08/Harris-Developed.jpg?fit=1200%2C582&ssl=15821200adminadmin2021-08-05 17:34:302021-08-06 11:42:27USGS Says One Third of Harris County Now Impervious Cover
On June 29, 2021, Harris County Commissioners approved two contracts for preliminary engineering on the Kingwood Diversion Ditch and Taylor Gully Projects. This week, I’ve been getting reports of boots on the ground. So I grabbed my camera and went looking for activity this morning. I found a soil survey truck at Kingwood Drive next to the Diversion Ditch. I also found regular surveyors on Taylor Gully about a block south of Woodridge Village.
Both activities are among the first steps in preliminary engineering. And both are among the first steps in finding flood-mitigation solutions for a huge percentage of Kingwood’s population.
This drone shot shows the surveying crew a little more than one block south of Woodridge Village on Taylor Gully.
Looking downstream in opposite direction toward Rustic Elm Bridge out of sight around bend.
The surveyors were capturing elevations of the banks, slopes, ditch bottom, and backslope swalesof Taylor Gully.
Taylor Gully Objectives and Scope
HCFCD has asked Idcus, Inc. to develop up to five conceptual alternative scenarios for modifying Taylor Gully. Alternative scenarios may include:
Expanding Detention On Woodridge Village Site so that no channel improvements are necessary.
Determining amount of detention and channel improvements necessary to ensure no adverse impact all the way to Lake Houston.
Finding the optimum balance between maximum flood protection and minimum construction costs.
Deliverables include:
Channel and basin layouts
Estimates of benefits for various levels of storms (100-year, etc.)
Right-of-way requirements
Cost estimates for right-of-way acquisition, engineering and construction management.
Performance metrics, i.e., estimated acreage of land inundation, number of structures in floodplain, number of structures flooded and miles of inundated roadway.
A scoring matrix to rank alternatives.
Scope of Taylor Gully Project includes the two halves of Woodridge Village outlined in gold above the ditch.
Kingwood Diversion Ditch Objectives and Scope
HCFCD hired Neel-Schaffer, Inc. for preliminary Kingwood Diversion Ditch engineering. They must:
Evaluate existing site conditions, previous studies, other projects that could affect this one, topography, rights-of-way, utilities, and soil surveys.
Evaluate existing bridges
Conduct and H&H analysis to assess existing and proposed conditions (from 2-year to 500-year storms).
Analyze Channel Improvements including the:
Impact of TIRZ #10’s latest design to replace the Northpark Bridge
Diversion structure at the confluence of Bens Branch and the Diversion Channel
Drop structures in lieu of a concrete lined channel to minimize high velocities due to the steep grade between Walnut Lane and Deer Ridge Estates Blvd.
Develop phased construction plans based on available funding, potential impacts and benefits.
Conduct two public engagement meetings and coordinate with community groups.
Deliverables include:
Surveys
Geotechnical investigations, i.e., bridge borings
Environmental assessment
“Jurisdictional” determination. Does this channel fall under the jurisdiction of the Army Corps as it nears the West Fork? If so, channel design may need to be altered.
Determination of detention pond requirements
Exploration for subsurface utilities
Obtaining permits from the Corps
Landscape architect services
Scope of Diversion Ditch Project runs from St. Martha Catholic Church in Montgomery County to the San Jacinto West Fork at River Grove Park. This is the ditch that runs past the fire station on Kingwood Drive.
Why These Two Projects First?
Both of these projects evolved from the Kingwood Drainage Analysis finalized late last year. That study identified nine channels that needed improvement. These two were recommended for immediate help because:
They help the largest number of people.
HCFCD already owns land to expand and deepen the Diversion Ditch.
Diversion Ditch enhancement will immediately take pressure off Ben’s Branch, and help flooding there.
Note that Ben’s Branch has already gone through a four-phase major maintenance project designed to restore its original conveyance.
Here is Harris County Flood Control District’s Summary of Results from the 600-page Kingwood Area Drainage Analysis.
A Good Sign
Both of these projects go far beyond maintenance, which portions of both of these ditches have already received. While we’re still far from construction, the work that kicked off this week will improve flood safety for a large part of Kingwood.
Posted by Bob Rehak on 8/4/2021
1436 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2021/08/20210804-RJR_8789.jpg?fit=1200%2C800&ssl=18001200adminadmin2021-08-04 14:00:282021-08-04 14:27:38Kingwood Diversion Ditch and Taylor Gully Preliminary Engineering Projects Begin
Digest: Updates on Six Lake Houston Area Flood-Related Stories
Below is a quick digest of six flood-related stories affecting the Lake Houston Area.
Dredging is a Slow Go
Mechanical dredgers are slowly working their way through the channel south of Royal Shores. It connects the East and West Forks of the San Jacinto. Without dredging, the dredging equipment itself would not be able to make it through the channel.
However, the pace of the dredging is painfully slow. You can see the progress by comparing the two pictures below. I took them 22 days apart.
At about 200 feet per week with about 2,000 more feet to go, they should reach the East Fork in about another ten weeks.
Several boaters have commented on how the dredges can wait hours for a pontoon to ferry dirt back to the placement site. Their net takeaway: very inefficient. During a July 8 meeting at the Kingwood Community Center, Stephen Costello called this method of dredging “unsustainable.” He’s sooooo right. We will run out of luck long before we run out of places to dredge.
Mechanical dredging (shown in the photos above) is far slower and less efficient than hydraulic. Great Lakes hydraulic dredges removed 500,000 cubic yards of sediment from the mouth bar area in just two months – July and August of 2019. DRC’s mechanical dredges removed another 600,000+ cubic yards in the 19 months between January 2020 and July 2021.
Interestingly, Google Earth shows that when the dredgers reach the East Fork, they will be closer to the Triple PG Sand Mine in Porter than the current placement area south of River Grove Park. The Triple PG mine will also be less than half the distance of a mine that the Army Corps previously pumped spoils to from the mouth bar– the Eagle Sorters Mine on the West Fork.
Hmmmm. Triple PG. A placement area for East Fork spoils? A return to hydraulic dredging? Interesting thoughts.
Seasonal Lowering of Lake Conroe
Seasonal lowering of Lake Conroe has started as planned. SJRA is releasing 75 cubic feet per second, according to their dashboard.
When the lowering started on August 2, a day late, the lake was at 200.87. So releasing 75 CFS has brought the lake down .19 feet, a little more than 2 inches. Barring large rainfalls, this rate should reach the objective of 200 feet by September 1.
The Lake Conroe Association is still fighting the lowering in Montgomery County District Court. Judge Mike Mays set a hearing date for Tuesday, August 24, 2021 at 2PM.
Tropics Heating Up
The National Hurricane Center shows two areas of concern in the Atlantic as of 2PM, Friday August 6th.
A few hundred miles south of the Cabo Verde Islands, a tropical wave (orange area) and a broad area of low pressure could turn into a tropical depression by late this weekend or early next week. Formation chance through 5 days…medium…60 percent.
Another tropical wave approaching the Lesser Antilles is a lower threat. NHC predicts development, if any, of this system will be slow and occur early next week. Formation chance through 5 days…low…20 percent.
NOAA Issues Mid-Season Hurricane Outlook
Another forecast released two days ago by NOAA says that atmospheric conditions are still conducive for an above-average hurricane season. See their predictions in the right hand column below. These numbers include the five named storms so far this season.
Attorney General Lawsuit Against Triple PG Mine Still Active
Craig Pritzlaff of the TCEQ assures me that despite visible lack of progress in the Attorney General’s lawsuit against the Triple PG mine for illegal discharges, the AG has not dropped the case. “Indeed, very few, if any, cases referred to the AG for civil prosecution are ever dropped,” he says. “Litigation, particularly environmental litigation, is a complicated and lengthy process. That process was further complicated by the COVID-19 pandemic, which halted court dockets across the State throughout 2020 and into 2021.”
Condos 250 Feet from 250,000 CFS
A Chinese developer is building yet more condos even closer to the West Fork in the Kings Harbor neighborhood.
During Harvey, more than 250,000 cubic feet per second came through this area. It flooded homes and businesses more than 10,000 feet from the river.
The developer is also hoping to sell/develop that grassy area in the bottom center of the photo for $1.45 million.
I guess money has a short memory.
That concludes this month’s digest.
Posted by Bob Rehak on 8/6/2021
1438 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.
USGS Says One Third of Harris County Now Impervious Cover
Did you know that one-third of the area in Harris County now has impervious cover? That Montgomery County had a 57.12% net increase of impervious surface area between 2001 and 2019? Or that 10% of land cover in the Lower 48 states changed during that same period? I discovered these and a multitude of other fascinating facts in a recently updated United States Geological Survey (USGS) website dedicated to monitoring changes in land cover, for example, from forested to developed.
When you live in an area for a long time, it’s easy to forget what happened two decades ago. And when you move to a new area, you just accept what is and don’t worry about what was.
But USGS gives you a quick and easy way to see and quantify changes in land use down to the county level. It’s useful in telling you where flood threats could develop over time and how fast they are developing.
About the USGS National Land Cover Database
USGS recently released updated land cover maps for the lower 48 United States. They show how the country’s landscapes have changed over an 18 year period in two- to three-year increments. It’s called the United States National Land Cover Database (NLCD). And it’s the fastest way to see how your county is changing.
Updates include 2001, 2004, 2006, 2008, 2011, 2013, 2016, and 2019.
Developed using Landsat imagery, NLCD classifies land cover into 16 groups with 30-meter resolution. The data includes both land-cover and urban imperviousness changes.
USGS claims 91 percent accuracy for the NLCD data. For more detail about how NLCD was developed see: Changes to the National Land Cover Database. More than nine billion pixels make up the land-cover dataset.
The USGS National Land Cover Database’s suite of GIS mapping products even includes a layer that defines the intensity of impervious surfaces across the United States. This information is used in runoff modeling, urban heat estimation, and a variety of other applications.
Mapping Land Cover Change in U.S. Over Time
Users can visualize land cover changes in the United States by accessing the the Enhanced Visualization and Analysis (EVA) tool. The online mapping tool was developed by USGS in partnership with the National Oceanic and Atmospheric Administration.
The tool allows users to select any county in the Lower-48 United States and generate a custom report on land cover change, developed areas, cropland change, and other factors.
Only one caution: the USGS site does not work with Apple’s Safari Browser. Mac users can use Firefox without problems, however. I have not tested other Mac browsers.
I ran two quick searches on Harris and Montgomery Counties by going to the EVA tool mentioned above. The findings astonished me.
Harris County Changes At a Glance
Between 2001 and 2019, in Harris County:
MoCo Changes at a Glance
During the same period, in Montgomery County:
Key Lesson
This database and GIS mapping system dramatize how quickly the region is growing and land use is changing.
Flood mitigation is or should be a two-pronged effort. We must fix problems that already exist downstream while hopefully preventing future problems from developing upstream. It’s not a just question of one county spending money to help prevent problems in another. It’s about surrounding counties protecting themselves. The outward expansion is relentless. People at the edge today will be downstream from someone else tomorrow.
There’s little anyone can do to change the FACT of development. But we can change the NATURE of development. If all new developments retained their own rain, no one would ever be doomed to the flood-mitigation treadmill of keeping up with ever-increasing amounts of upstream runoff.
Montgomery County already has a serious flooding problem of its own. Thousands of people flooded there during Harvey and Imelda.
Posted by Bob Rehak on 8/5/2021 based on USGS information
1437 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.
Kingwood Diversion Ditch and Taylor Gully Preliminary Engineering Projects Begin
On June 29, 2021, Harris County Commissioners approved two contracts for preliminary engineering on the Kingwood Diversion Ditch and Taylor Gully Projects. This week, I’ve been getting reports of boots on the ground. So I grabbed my camera and went looking for activity this morning. I found a soil survey truck at Kingwood Drive next to the Diversion Ditch. I also found regular surveyors on Taylor Gully about a block south of Woodridge Village.
Both activities are among the first steps in preliminary engineering. And both are among the first steps in finding flood-mitigation solutions for a huge percentage of Kingwood’s population.
Taylor Gully Objectives and Scope
HCFCD has asked Idcus, Inc. to develop up to five conceptual alternative scenarios for modifying Taylor Gully. Alternative scenarios may include:
Deliverables include:
Kingwood Diversion Ditch Objectives and Scope
HCFCD hired Neel-Schaffer, Inc. for preliminary Kingwood Diversion Ditch engineering. They must:
Walnut Lane and Deer Ridge Estates Blvd.
Deliverables include:
Why These Two Projects First?
Both of these projects evolved from the Kingwood Drainage Analysis finalized late last year. That study identified nine channels that needed improvement. These two were recommended for immediate help because:
Note that Ben’s Branch has already gone through a four-phase major maintenance project designed to restore its original conveyance.
Here is Harris County Flood Control District’s Summary of Results from the 600-page Kingwood Area Drainage Analysis.
A Good Sign
Both of these projects go far beyond maintenance, which portions of both of these ditches have already received. While we’re still far from construction, the work that kicked off this week will improve flood safety for a large part of Kingwood.
Posted by Bob Rehak on 8/4/2021
1436 Days since Hurricane Harvey