Still three weeks from the peak of hurricane season (September 10), the tropical forecast has suddenly become more active. The latest seven-day outlook from the National Hurricane Center (NHC) shows four areas of concern. Two will not affect the Texas Gulf Coast. Eventually, the other two could get close.
The red area at the right currently has a 70% chance of tropical formation in the next seven days.
The orange area has a 40% chance. Environmental conditions are only marginally conducive for further development of this system, but a tropical depression could still form during the next couple of days while it moves west-northwestward at 10 to 15 mph across the central tropical Atlantic.
Neither of those systems poses a threat to Texas.
The yellow area in the middle approaching the Lesser Antilles has a 30% chance of formation.
The yellow area on the left will move toward the Gulf of Mexico by early next week. It also has a 30% chance of tropical formation.
The NHC updates its website several times a day during hurricane season. So bookmark it and check back often for the latest forecasts.
Local Impact Felt by Next Tuesday
Jeff Lindner, Harris County’s meteorologist, has been sending out updates all week long on the last system. Here’s what he had to say on Friday morning, 8/18/23. “A low chance of tropical cyclone formation remains possible over the western Gulf early to mid next week.”
“A tropical wave will reach the eastern Gulf of Mexico late this weekend. As high pressure over Texas lifts northward and centers over the Midwest early next week, this wave will continue westward and approach the Texas coast by Tuesday or Wednesday,” said Lindner.
Possibilities include a tropical wave, tropical depression, or weak tropical storm moving inland along the lower or middle Texas coast. Conditions appear to be generally favorable for some slow development, but dry air is lurking along the U.S. Gulf coast that could wrap into any developing system. Also any developing system could encounter wind shear over the western Gulf from the outflow of powerful Hurricane Hilary in the eastern Pacific Ocean.
Any Development Most Likely Near Coast
“With that said, the system will be moving over warm sea surface temperatures and systems, especially in the NW Gulf under the right conditions can tighten up just prior to landfall. This may be a situation where whatever is going to happen with any development occurs very near the coast,” said Lindner.
Most Moisture Near Coast and West of Houston
Lindner concludes, “Regardless of development, tropical moisture will surge into the Texas coast as early as late Monday, but more likely Tuesday or Wednesday. For now, the greatest moisture looks to remain along and south of the I-10 corridor with areas north of I-10 still under the influence of the high pressure ridge over the Midwest. There will likely be a strong gradient in rain chances from south to north over the area next week with the potential for some desperately needed rainfall across the coastal locations.”
Subsiding air from the high to the north will determine how far inland the moisture and rain/bands reach. This map from the National Weather Service (NWS) helps visualize what the situation will look like by Monday, August 21.
Flood Risk Less than 5%
The risk of excessive rainfall that could cause flash flooding is less than 5% according to the NWS.
It’s pretty sad when you start wishing for a tropical storm. But we sure could use something to break the drought and cool us off. Yesterday’s high of 105 was the highest temp recorded in Houston since 1909, according to ABC13. And it could get close to that again today.
Posted by Bob Rehak on 8/18/23
2180 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/08/two_atl_7d0.png?fit=900%2C665&ssl=1665900adminadmin2023-08-18 09:58:232023-08-18 10:12:04Tropical Forecast Suddenly More Active
The drainage project currently underway down the median of Northpark Drive represents only part of the drainage improvements for the expansion project. Another parallel drainage system about 250 yards north of Northpark will carry additional stormwater all the way from U.S. 59 to the Kingwood Diversion Ditch and Bens Branch. Project engineers call it “Ditch One.”
Additional Parallel Drainage Route North of Northpark
In the satellite image below, the two triangles at 59 surround the wooded areas at the Northpark entrance to Kingwood. Detention ponds similar to those at the Kingwood Drive entry will replace those wooded areas.
Northpark Drive cuts left to right through the frame just above the center. Red line shows route for supplementary drainageand where flow splits in twoat Diversion Ditch.
The water surface elevation of the Northpark ponds will be several feet below grade, as you can see in this video.
The difference between the surface of the ponds and ground level will provide storage capacity to offset the increase in impervious cover created by the expansion of the roadway.
When the south pond fills up, it will overflow to the north pond. And when the north pond fills up, it will drain to the east via an eight-foot culvert. The eight-foot culvert by itself provides additional underground water storage before it reaches the eastbound ditch.
That culvert will go under Loop 494 and the UnionPacific railroad tracks, then turn left (north) until it gets past the businesses on the north side of Northpark. From there, it will empty into a ditch that heads back east again. See below.
Looking East from over 494 toward St. Martha Catholic Church. Arrows in distance show where Diversion Ditch splits off from Bens Branch.Note part of Northpark Drive in upper right.
Ditch One is barely visible in the photo above for two reasons.
The tree canopy is dense this time of year.
Due to lack of maintenance over the years, trees have grown up in the ditch. Contractors will have to clear them out to restore conveyance before completion of the project.
The Big Split
Once water in the ditch reaches the detention basins south of St. Martha Catholic Church, part of the water will enter the Kingwood Diversion Ditch and head south along the western edge of Woodland Hills. The rest will continue east and go down Bens Branch which angles diagonally toward Town Center and eventually empties into Lake Houston near Kings Harbor.
Looking N toward St. Martha in upper left at where flow in Ditch One splits into Diversion Ditch (foreground) and Bens Branch (right)
Why Diversion Ditch is Called Diversion Ditch
The split you see in the red line below is why the Diversion Ditch is called the Diversion Ditch. It is a man-made channel designed to take stormwater out of the natural channel (Bens Branch) to reduce flood risk for homes in the center of Kingwood.
Reverse angle looking Stoward Diversion Ditch.
In the photo above, Bens Branch flows R to L. The Diversion Ditch flows south toward Kingwood Drive and Lake Houston. The blue water towers in background are near the firehouse on Kingwood Drive and Deer Ridge Park.
Looking north at recent CoH excavation under North Park at Diversion Ditch.
Eventually, the Diversion Ditch itself will expand to match the increased conveyance you see under the bridges. Some engineers feel that constrictions like you see above contributed more to flooding than lack of capacity in the ditch itself.
The route that Bens Branch will take to get under Northpark Drive east of the diversion ditch has yet to be determined. However, that phase of the project is still at least three years away. TxDoT is currently evaluating multiple alternatives suggested by engineers for the Lake Houston Redevelopment Authority. For more videos of the project, drainage studies and construction plans, see the LHRA website.
Colony Ridge, the world’s largest trailer park, fails to meet Liberty County regulations for the construction of stormwater detention basins and ditches. The development’s basins and ditches routinely lack erosion controls such as grass and backslope interceptor swales. The resulting erosion can reduce the conveyance of streams, increase flood risk and threaten property both inside the development and downstream. The failure to follow those regulations imposes a hidden tax on residents of Liberty and surrounding counties.
Pages 152 and 153 of the regulations also require backslope drain systems to “intercept sheet flow which otherwise would flow over the banks of drainage channels leading to erosion of the side slopes.” Swales behind the edges of basins and channels trap stormwater. Pipes then carry it to the bottom of the ditch or basin so that it won’t erode side slopes.
What Ditches/Detention Basins Should Look Like
The photo below shows a Harris County ditch with grass on the side slopes and pipes that lead from backslope swales to the bottom of the channel. Note how they reduce erosion and sedimentation.
Harris County ditch which follows regulations similar to Liberty County’s. Compare the Colony Ridge ditches below.
Compare Requirements to Photos
I took the pictures below on 8/12/23 from a helicopter while flying over Colony Ridge in Liberty County. Note the lack of grass and interceptor inlets/outlets. Also note the severe erosion that results.
Note severe erosion on banks of pond. Also note lack of backslope swales, inlets, and outlets in base of pond.No backslope interceptor system. No grass.No backslope interceptor system. No grass.No backslope interceptor system. No grasson sides of ditch.Ditto.Ditto
In some cases, the ditches and detention basins don’t even have perimeter maintenance roads and the erosion is cutting into people’s back yards.
Colony Ridge resident losing back of property due to ditch erosion.
The Largest Development Few Know About
Colony Ridge is large and growing rapidly. The satellite image below shows how it has virtually doubled in size within the last two years as it has grown from left to right and bottom to top. The large area in the lower left began developing around 2011. Those lines that look like hashmarks are thousands of mobile homes.
This satellite image taken in July 2023 does not even show the development’s current extent. Much of the area in the upper right below the clouds was cleared since then.See below.Portion of Colony Ridge in upper right of satellite photo has now been cleared.
Colony Ridge already comprises more than 30 square miles. That makes it approximately one third the size of the area inside Houston’s 610 loop.
Mostly mobile homes and rivers of mud as far as the eye can see.
Erosion a Major Issue
Colony Ridge drains into three watersheds: the East Fork San Jacinto, Luce Bayou and Tarkington Bayou. And all of them drain into Lake Houston. That will make erosion from Colony Ridge Harris and Liberty County’s problem forever.
“Erosion and sedimentation can have very serious effects on storm water drainage.”
“Erosion can cause slope failures, increase roughness coefficients, and generally reduce the efficiency of drainage channels. However, sediment deposition can clog drainage culverts and reduce the available conveyance in open channels.”
“Erosion can significantly reduce the maintainability of drainage facilities and increase the cost of maintenance by increasing the frequency with which repairs are required.”
LJA engineering wrote a letter to the Liberty County Engineer that underscores the need to plan ahead as the county transitions from rural to urban. “While limited regulation of development in a rural area may not significantly impact drainage issues, Liberty County is now challenged with explosive population growth and a particularly high percentage of socially vulnerable residents…” said the letter.
Hidden Cost to Downstream Residents
Most people in Harris County don’t even know that Colony Ridge exists. Yet the drainage practices there affect dredging costs downstream. The City of Houston, Harris County and Army Corps spent almost a quarter billion dollars dredging the headwaters of Lake Houston between Harvey and mid-2021.
Clearly, not all of that sediment came from Colony Ridge. However, the development practices in Colony Ridge and other developments like it will set the pattern for the future.
Developments are virtually impossible to change after people start building next to undersized basins and ditches that erode more with every substantial rain.
What You See Makes You Question What You Don’t See
Substandard construction practices make you wonder about engineering practices. Did Colony Ridge engineers produce reliable, accurate estimates of drainage needs? Are those ditches and detention basins sized properly? Will they hold enough runoff to protect residents?
Probably not. Even assuming engineers and contractors did their jobs properly (a big assumption), Liberty County still defines a 100 year/24 hour rainfall as 13.5 inches (see page 108), a rate associated with pre-Atlas 14 days.
Atlas 14 catalogs the current national precipitation frequency standards for every community in the U.S.
However, the phrase “Atlas 14” appears nowhere in the 2019 Liberty County Subdivision and Development Regulations.
But NOAA now defines a 100 year/24 hour rainfall for nearby Cleveland, TX, as 17.1 inches – a 27% increase above the current Liberty County standard. So in a hundred-year rainfall, everything you see in Colony Ridge will be 27% short of capacity. Few people likely understand this.
Consider also that NOAA is already working on replacing Atlas 14 with Atlas 15!
Posted by Bob Rehak on 8/16/23
2178 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/2023/08/20230812-RJR_5768-e1692197968560.jpg?fit=1100%2C733&ssl=17331100adminadmin2023-08-16 11:46:552023-08-16 23:01:40Colony Ridge Stormwater Detention Basins, Ditches Fail to Meet Liberty County Standards
Tropical Forecast Suddenly More Active
Still three weeks from the peak of hurricane season (September 10), the tropical forecast has suddenly become more active. The latest seven-day outlook from the National Hurricane Center (NHC) shows four areas of concern. Two will not affect the Texas Gulf Coast. Eventually, the other two could get close.
Chances of Tropical Formation
According to the NHC 8 a.m. update:
The NHC updates its website several times a day during hurricane season. So bookmark it and check back often for the latest forecasts.
Local Impact Felt by Next Tuesday
Jeff Lindner, Harris County’s meteorologist, has been sending out updates all week long on the last system. Here’s what he had to say on Friday morning, 8/18/23. “A low chance of tropical cyclone formation remains possible over the western Gulf early to mid next week.”
“A tropical wave will reach the eastern Gulf of Mexico late this weekend. As high pressure over Texas lifts northward and centers over the Midwest early next week, this wave will continue westward and approach the Texas coast by Tuesday or Wednesday,” said Lindner.
Possibilities include a tropical wave, tropical depression, or weak tropical storm moving inland along the lower or middle Texas coast. Conditions appear to be generally favorable for some slow development, but dry air is lurking along the U.S. Gulf coast that could wrap into any developing system. Also any developing system could encounter wind shear over the western Gulf from the outflow of powerful Hurricane Hilary in the eastern Pacific Ocean.
Any Development Most Likely Near Coast
“With that said, the system will be moving over warm sea surface temperatures and systems, especially in the NW Gulf under the right conditions can tighten up just prior to landfall. This may be a situation where whatever is going to happen with any development occurs very near the coast,” said Lindner.
Most Moisture Near Coast and West of Houston
Lindner concludes, “Regardless of development, tropical moisture will surge into the Texas coast as early as late Monday, but more likely Tuesday or Wednesday. For now, the greatest moisture looks to remain along and south of the I-10 corridor with areas north of I-10 still under the influence of the high pressure ridge over the Midwest. There will likely be a strong gradient in rain chances from south to north over the area next week with the potential for some desperately needed rainfall across the coastal locations.”
Subsiding air from the high to the north will determine how far inland the moisture and rain/bands reach. This map from the National Weather Service (NWS) helps visualize what the situation will look like by Monday, August 21.
Flood Risk Less than 5%
The risk of excessive rainfall that could cause flash flooding is less than 5% according to the NWS.
It’s pretty sad when you start wishing for a tropical storm. But we sure could use something to break the drought and cool us off. Yesterday’s high of 105 was the highest temp recorded in Houston since 1909, according to ABC13. And it could get close to that again today.
Posted by Bob Rehak on 8/18/23
2180 Days since Hurricane Harvey
More Drainage for Northpark Drive Expansion Project
The drainage project currently underway down the median of Northpark Drive represents only part of the drainage improvements for the expansion project. Another parallel drainage system about 250 yards north of Northpark will carry additional stormwater all the way from U.S. 59 to the Kingwood Diversion Ditch and Bens Branch. Project engineers call it “Ditch One.”
Additional Parallel Drainage Route North of Northpark
In the satellite image below, the two triangles at 59 surround the wooded areas at the Northpark entrance to Kingwood. Detention ponds similar to those at the Kingwood Drive entry will replace those wooded areas.
The water surface elevation of the Northpark ponds will be several feet below grade, as you can see in this video.
When the south pond fills up, it will overflow to the north pond. And when the north pond fills up, it will drain to the east via an eight-foot culvert. The eight-foot culvert by itself provides additional underground water storage before it reaches the eastbound ditch.
That culvert will go under Loop 494 and the UnionPacific railroad tracks, then turn left (north) until it gets past the businesses on the north side of Northpark. From there, it will empty into a ditch that heads back east again. See below.
Ditch One is barely visible in the photo above for two reasons.
The Big Split
Once water in the ditch reaches the detention basins south of St. Martha Catholic Church, part of the water will enter the Kingwood Diversion Ditch and head south along the western edge of Woodland Hills. The rest will continue east and go down Bens Branch which angles diagonally toward Town Center and eventually empties into Lake Houston near Kings Harbor.
Why Diversion Ditch is Called Diversion Ditch
The split you see in the red line below is why the Diversion Ditch is called the Diversion Ditch. It is a man-made channel designed to take stormwater out of the natural channel (Bens Branch) to reduce flood risk for homes in the center of Kingwood.
In the photo above, Bens Branch flows R to L. The Diversion Ditch flows south toward Kingwood Drive and Lake Houston. The blue water towers in background are near the firehouse on Kingwood Drive and Deer Ridge Park.
The City just finished cleaning out under the Northpark bridges at the Diversion Ditch. See results below.
Eventually, the Diversion Ditch itself will expand to match the increased conveyance you see under the bridges. Some engineers feel that constrictions like you see above contributed more to flooding than lack of capacity in the ditch itself.
Kingwood Drainage Priorities
Regardless, expansion of the Diversion Ditch was one of the top two priorities of the Kingwood Area Drainage Analysis. That project has not yet started.
Bens Branch has already gone through four phases of de-silting and de-snagging to help restore its conveyance. That was part of a major maintenance program by HCFCD after Harvey.
The route that Bens Branch will take to get under Northpark Drive east of the diversion ditch has yet to be determined. However, that phase of the project is still at least three years away. TxDoT is currently evaluating multiple alternatives suggested by engineers for the Lake Houston Redevelopment Authority. For more videos of the project, drainage studies and construction plans, see the LHRA website.
To see how ALL the ditches and streams in Kingwood connect, visit the Harris County Flood Education Mapping Tool. If you see a blockage in a Harris County Ditch, you can request service at HCFCD.
Posted by Bob Rehak on 8/17/2023
2189 Days since Hurricane Harvey
Colony Ridge Stormwater Detention Basins, Ditches Fail to Meet Liberty County Standards
Colony Ridge, the world’s largest trailer park, fails to meet Liberty County regulations for the construction of stormwater detention basins and ditches. The development’s basins and ditches routinely lack erosion controls such as grass and backslope interceptor swales. The resulting erosion can reduce the conveyance of streams, increase flood risk and threaten property both inside the development and downstream. The failure to follow those regulations imposes a hidden tax on residents of Liberty and surrounding counties.
No Bare, Earthen Slopes Allowed
Page 100 of the Liberty County Subdivision and Development Regulations updated in 2019 states that, “All drainage facilities must be designed and maintained in a manner which minimizes the potential for damage due to erosion. No bare earthen slopes will be allowed.“
Backslope Drain Systems Required
Pages 152 and 153 of the regulations also require backslope drain systems to “intercept sheet flow which otherwise would flow over the banks of drainage channels leading to erosion of the side slopes.” Swales behind the edges of basins and channels trap stormwater. Pipes then carry it to the bottom of the ditch or basin so that it won’t erode side slopes.
What Ditches/Detention Basins Should Look Like
The photo below shows a Harris County ditch with grass on the side slopes and pipes that lead from backslope swales to the bottom of the channel. Note how they reduce erosion and sedimentation.
Compare Requirements to Photos
I took the pictures below on 8/12/23 from a helicopter while flying over Colony Ridge in Liberty County. Note the lack of grass and interceptor inlets/outlets. Also note the severe erosion that results.
In some cases, the ditches and detention basins don’t even have perimeter maintenance roads and the erosion is cutting into people’s back yards.
Colony Ridge resident losing back of property due to ditch erosion.
The Largest Development Few Know About
Colony Ridge is large and growing rapidly. The satellite image below shows how it has virtually doubled in size within the last two years as it has grown from left to right and bottom to top. The large area in the lower left began developing around 2011. Those lines that look like hashmarks are thousands of mobile homes.
Erosion a Major Issue
Colony Ridge drains into three watersheds: the East Fork San Jacinto, Luce Bayou and Tarkington Bayou. And all of them drain into Lake Houston. That will make erosion from Colony Ridge Harris and Liberty County’s problem forever.
During floods, erosion will reduce the conveyance of downstream channels and rivers. Page 148 of the Liberty County Subdivision and Development Regulations has this to say about the effects of erosion and sedimentation.
LJA engineering wrote a letter to the Liberty County Engineer that underscores the need to plan ahead as the county transitions from rural to urban. “While limited regulation of development in a rural area may not significantly impact drainage issues, Liberty County is now challenged with explosive population growth and a particularly high percentage of socially vulnerable residents…” said the letter.
Hidden Cost to Downstream Residents
Most people in Harris County don’t even know that Colony Ridge exists. Yet the drainage practices there affect dredging costs downstream. The City of Houston, Harris County and Army Corps spent almost a quarter billion dollars dredging the headwaters of Lake Houston between Harvey and mid-2021.
Clearly, not all of that sediment came from Colony Ridge. However, the development practices in Colony Ridge and other developments like it will set the pattern for the future.
Developments are virtually impossible to change after people start building next to undersized basins and ditches that erode more with every substantial rain.
What You See Makes You Question What You Don’t See
Substandard construction practices make you wonder about engineering practices. Did Colony Ridge engineers produce reliable, accurate estimates of drainage needs? Are those ditches and detention basins sized properly? Will they hold enough runoff to protect residents?
Probably not. Even assuming engineers and contractors did their jobs properly (a big assumption), Liberty County still defines a 100 year/24 hour rainfall as 13.5 inches (see page 108), a rate associated with pre-Atlas 14 days.
Atlas 14 catalogs the current national precipitation frequency standards for every community in the U.S.
However, the phrase “Atlas 14” appears nowhere in the 2019 Liberty County Subdivision and Development Regulations.
But NOAA now defines a 100 year/24 hour rainfall for nearby Cleveland, TX, as 17.1 inches – a 27% increase above the current Liberty County standard. So in a hundred-year rainfall, everything you see in Colony Ridge will be 27% short of capacity. Few people likely understand this.
Consider also that NOAA is already working on replacing Atlas 14 with Atlas 15!
Posted by Bob Rehak on 8/16/23
2178 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.