The Briefing Room
State Chapters => Texas => Topic started by: Elderberry on February 20, 2019, 03:34:00 pm
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Houston Chronicle by Zach Despart Feb. 19, 2019
The Harris County Flood Control District is set to receive a $320,000 federal grant to study the feasibility of constructing deep underground tunnels to move stormwater to the Houston Ship Channel without overburdening the area’s bayous.
The grant, from the U.S. Economic Development Administration, will fund a four-month investigation to determine whether such tunnels would be a practical and cost-effective addition to the county’s long-term flood protection strategy. The flood control district has begun work on scores of projects funded by the $2.5 billion flood bond approved last summer, though none to date include underground tunnels.
“The study is basically to look at our ground conditions, including our groundwater table, and compare that to existing technology in the tunnel industry to see if there’s a match,†said Russ Poppe, executive director of the flood control district. “If that’s true, then we can start looking at costs, routes and opportunities we can potentially pursue.â€
Engineers envision a system in which tunnels at least 20 feet wide and 150 feet deep use gravity to move water from upstream bayous to the ship channel, in some cases a distance of 30 miles. The region’s flatness, in some areas less than one foot of elevation change per mile, presents a significant obstacle.
More: https://www.houstonchronicle.com/news/houston-texas/houston/article/Harris-County-poised-to-receive-grant-to-study-13628727.php (https://www.houstonchronicle.com/news/houston-texas/houston/article/Harris-County-poised-to-receive-grant-to-study-13628727.php)
So tunnels would be better than wider and deeper bayous and ditches? A tunnel 150 feet deep would be below the water level of the Ship Channel. Are they going to pump this water?
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So tunnels would be better than wider and deeper bayous and ditches? A tunnel 150 feet deep would be below the water level of the Ship Channel. Are they going to pump this water?
As long as the tunnel outlet is lower than the inlet, gravity will move the water regardless of depth in between. Works the same as a gravity syphon with a hose.
The problem is areas where it is already built up without room for ditches this big.
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As long as the tunnel outlet is lower than the inlet, gravity will move the water regardless of depth in between. Works the same as a gravity syphon with a hose.
The problem is areas where it is already built up without room for ditches this big.
If those tunnel bottoms didn't have a continuous slope gradient, then after a flood, there would remain a stagnant mosquito haven pool at every dip of the tunnel. At least bayous have wildlife that devour mosquitos.
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If those tunnel bottoms didn't have a continuous slope gradient, then after a flood, there would remain a stagnant mosquito haven pool at every dip of the tunnel. At least bayous have wildlife that devour mosquitos.
I would expect it to be full of water except at the inlet and outlet.
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I would expect it to be full of water except at the inlet and outlet.
So for each flood event, the flood water would have to push all the water in the fully filled tunnel out to the ship channel before any new flood water was able to be discharged? If it was a fast rising flood, the water, taking paths of least resistance would not even enter the tunnel.
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So for each flood event, the flood water would have to push all the water in the fully filled tunnel out to the ship channel before any new flood water was able to be discharged? If it was a fast rising flood, the water, taking paths of least resistance would not even enter the tunnel.
Gravity still works, even in a flood. If water comes to mouth, it is going to flow.
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Gravity still works, even in a flood. If water comes to mouth, it is going to flow.
Had involvement in this as a EHCMA participant back in the early '90's. Easy solution would be to dredge the HSC, but no one wanted to open that can of worms.
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Had involvement in this as a EHCMA participant back in the early '90's. Easy solution would be to dredge the HSC, but no one wanted to open that can of worms.
This is to get the water to the HSC, the backup before the channel.
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Gravity still works, even in a flood. If water comes to mouth, it is going to flow.
Eventually. And maybe not where you want it to.
For your fully filled tunnel, except for each end. Say one end just below Addicks Reservoir, with the other end into Buffalo bayou. For a distance of say 30 miles.
How much force would you imagine that flood water entering the unfilled end of that fully filled 30 mile tunnel would be needed to overcome both the inertia of all that water as well as the stationary friction of the water interface with the tunnel surface? And much time would be needed before the pipe was fully filled with new flood water?
I think you made a big mistake stating that only the ends of the tunnel would not be filled. That tunnel would have to be empty before any flood to be any help at all.
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Eventually. And maybe not where you want it to.
For your fully filled tunnel, except for each end. Say one end just below Addicks Reservoir, with the other end into Buffalo bayou. For a distance of say 30 miles.
How much force would you imagine that flood water entering the unfilled end of that fully filled 30 mile tunnel would be needed to overcome both the inertia of all that water as well as the stationary friction of the water interface with the tunnel surface? And much time would be needed before the pipe was fully filled with new flood water?
I think you made a big mistake stating that only the ends of the tunnel would not be filled. That tunnel would have to be empty before any flood to be any help at all.
How fast does pressure differential travel in an incompressible fluid?
I may be wrong. But I have found no discussion of pumps with this one or the ones already existing in DC.
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A wild kayak ride?
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How fast does pressure differential travel in an incompressible fluid?
I may be wrong. But I have found no discussion of pumps with this one or the ones already existing in DC.
You are looking at the wrong area. The tunnel is a "Pipe". You should be looking at the dynamics of non-steady viscous flows in pipe.
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You are looking at the wrong area. The tunnel is a "Pipe". You should be looking at the dynamics of non-steady viscous flows in pipe.
I give up. You win. This won't work and the ones they have already built in other areas don't work either.
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I give up. You win. This won't work and the ones they have already built in other areas don't work either.
As kids we used to explore for miles under the city in the storm sewers. Not during a flood, mind you, and none of them were filled with water. Well, other than a trickle flow.
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As kids we used to explore for miles under the city in the storm sewers. Not during a flood, mind you, and none of them were filled with water. Well, other than a trickle flow.
You should let San Antonio know the tunnels they have used for a couple decades won't work.
https://www.expressnews.com/150years/major-stories/article/History-River-Tunnel-0711-6378378.php (https://www.expressnews.com/150years/major-stories/article/History-River-Tunnel-0711-6378378.php)
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I thought this idea was proposed 20-30 years ago and scrapped back then?
3rd reservoir has also been proposed.
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You should let San Antonio know the tunnels they have used for a couple decades won't work.
https://www.expressnews.com/150years/major-stories/article/History-River-Tunnel-0711-6378378.php (https://www.expressnews.com/150years/major-stories/article/History-River-Tunnel-0711-6378378.php)
Aren't you the one that just said they don't work?
You tell them.
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This is to get the water to the HSC, the backup before the channel.
Having a cleaner and deeper HSC would have taken a first flush load off all the ancillary tribuataries.... Greens, Buffalo, Sims, etc.
Hydrology studies confirmed, but again...... No one wanted the issues associated with dredging the HSC.
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Having a cleaner and deeper HSC would have taken a first flush load off all the ancillary tribuataries.... Greens, Buffalo, Sims, etc.
Hydrology studies confirmed, but again...... No one wanted the issues associated with dredging the HSC.
Houston Ship Channel gets dredged from time to time already. It will silt up and have to maintain the depth.
Harvey-Related Dredging Of Houston Ship Channel Almost Done
https://www.houstonpublicmedia.org/articles/news/city-of-houston/2018/03/29/276020/harvey-related-dredging-of-houston-ship-channel-almost-done/ (https://www.houstonpublicmedia.org/articles/news/city-of-houston/2018/03/29/276020/harvey-related-dredging-of-houston-ship-channel-almost-done/)
However, this project is about getting the water to the Houston Ship Channel.
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Is a massive tunnel system the answer to Houston’s flood woes?
Other Texas cities have built underground channels to divert stormwater. Experts say it might not be the right way to go for Houston, but that it's still worth exploring.
Texas Tribune by Natalia Alamdari July 6, 2018
https://www.texastribune.org/2018/07/06/hurricane-harvey-floods-houston-water-tunnel/ (https://www.texastribune.org/2018/07/06/hurricane-harvey-floods-houston-water-tunnel/)
So would such a tunnel system really be a logical solution for Houston’s flood woes?
Drilled 100 to 200 feet underground, the underground channels act as temporary storage for floodwater during intense rainstorms, said Larry Larson, a senior policy adviser at the Association of State Floodplain Managers. Once the rain has stopped, the stormwater can be used for a variety of purposes. It can be pumped back to the surface into a river or wetlands or even used to recharge aquifers.
If cities have a section of river that regularly overflows, a tunnel can convey extra water underground and help reduce the amount of water that flows onto land during storms, said Christof Spieler, project manager of the Greater Houston Flood Mitigation Consortium. Large-scale tunnels can also act as an additional set of waterways, taking pressure off undersized drainage networks, he said.
But Larson and Spieler said it's hard to tell if such a system would make sense for Houston — a low-lying coastal city that's experienced three 500-year floods in the past three years.
The area's soft soil and high groundwater table would likely complicate construction, Larson said. And while most cities have flood zones concentrated around rivers and other bodies of water, Spieler said Houston experiences more dispersed flooding
"It's not one big waterway, but dozens of them, and no clear floodplains," he said.
Because flood patterns vary across watersheds, Spieler said what might be a good solution in one part of the county wouldn't necessarily be the best choice in another.
“[Houston has] the worst of conditions — huge development and you’re in terrain that’s flat as a pancake. You can’t get the water out,†Larson said. “You’re even subject to coastal storm surge. Houston’s really in a bullseye there.â€
More at link above.
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Houston Ship Channel gets dredged from time to time already. It will silt up and have to maintain the depth.
Harvey-Related Dredging Of Houston Ship Channel Almost Done
https://www.houstonpublicmedia.org/articles/news/city-of-houston/2018/03/29/276020/harvey-related-dredging-of-houston-ship-channel-almost-done/ (https://www.houstonpublicmedia.org/articles/news/city-of-houston/2018/03/29/276020/harvey-related-dredging-of-houston-ship-channel-almost-done/)
However, this project is about getting the water to the Houston Ship Channel.
LOL.... Cursory "minor surgery" dredging to make sure waterways are operable for barges and ships.
I am talking DREDGING to clean the sucker up. Big difference, and a game changer that would help eleviate problems upstream.
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LOL.... Cursory "minor surgery" dredging to make sure waterways are operable for barges and ships.
I am talking DREDGING to clean the sucker up. Big difference, and a game changer that would help eleviate problems upstream.
It is already dredged to 40 feet. How deep do you think they should go?
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It is already dredged to 40 feet. How deep do you think they should go?
LOL....you have the patience of Job. :laugh:
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LOL....you have the patience of Job. :laugh:
Besides the Washburn Tunnel with the top at 45 feet deep, there are a few other issues going much deeper.
(http://i68.tinypic.com/2zf8nqt.png)
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It is already dredged to 40 feet. How deep do you think they should go?
I think that depth was mid-channel wasn't it? (for waterway navigation) I am talking about the volume near or prior to industrial development.
During the ECHMA meetings, the word "epic" was often used to describe what "best case" drainage benefits say from dredging the HSC from inside the loop to the inlet of the bay. OF course a high priced feasibility/ cost effectiveness study shot it down. And of course this is several years before Allison or Harvey.
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I think that depth was mid-channel wasn't it? (for waterway navigation) I am talking about the volume near or prior to industrial development.
During the ECHMA meetings, the word "epic" was often used to describe what "best case" drainage benefits say from dredging the HSC from inside the loop to the inlet of the bay. OF course a high priced feasibility/ cost effectiveness study shot it down. And of course this is several years before Allison or Harvey.
So reduce the depth to about 6 feet? How would that help?
Galveston Bay is only about 6 feet deep except where they dredged for the channel.
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So reduce the depth to about 6 feet? How would that help?
Galveston Bay is only about 6 feet deep except where they dredged for the channel.
Bay depth is inmaterial when considering silting and sludge in a drainage scenario on the HSC. Existing silt and sludge is what displaces the water than needs to be removed upstream.
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So reduce the depth to about 6 feet? How would that help?
Galveston Bay is only about 6 feet deep except where they dredged for the channel.
Wagons used to cross Galveston Bay from Smith Point to Eagle Point.
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Bay depth is inmaterial when considering silting and sludge in a drainage scenario on the HSC. Existing silt and sludge is what displaces the water than needs to be removed upstream.
I think that depth was mid-channel wasn't it? (for waterway navigation) I am talking about the volume near or prior to industrial development.
The original Houston Ship Channel was dredged to 100 feet wide, 6 feet deep.
https://aoghs.org/transportation/houston-ship-channel/ (https://aoghs.org/transportation/houston-ship-channel/)
https://tshaonline.org/handbook/online/articles/rhh11 (https://tshaonline.org/handbook/online/articles/rhh11)
Now it is dredged 45 feet deep for several hundred feet wide.
(http://i66.tinypic.com/2q9e1vs.png)
https://www.swg.usace.army.mil/Portals/26/docs/Navigation/Channel_Survey_Maps/HS/MLLW/HS_07_BGB_20181006_CS_EX_41_MLLW_68000_83305.pdf (https://www.swg.usace.army.mil/Portals/26/docs/Navigation/Channel_Survey_Maps/HS/MLLW/HS_07_BGB_20181006_CS_EX_41_MLLW_68000_83305.pdf)
It is not silted up and it is maintained at these depths and widths.
What do you imagine with the information I have shared with you could be done in the channel to significantly improve? And keep in mind the tunnel project is to get the water to the Houston Ship Channel, not replace it.
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Wagons used to cross Galveston Bay from Smith Point to Eagle Point.
On Redfish Bar, or Barra de las Pescador Encarnador.
https://galvbaydata.org/www.galvbaydata.org/Portals/2/StateOfTheBay/2011/Chapters/Chapter%203%20-%20The%20Human%20Role%20Past.pdf (https://galvbaydata.org/www.galvbaydata.org/Portals/2/StateOfTheBay/2011/Chapters/Chapter%203%20-%20The%20Human%20Role%20Past.pdf)
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The original Houston Ship Channel was dredged to 100 feet wide, 6 feet deep.
https://aoghs.org/transportation/houston-ship-channel/ (https://aoghs.org/transportation/houston-ship-channel/)
https://tshaonline.org/handbook/online/articles/rhh11 (https://tshaonline.org/handbook/online/articles/rhh11)
Now it is dredged 45 feet deep for several hundred feet wide.
(http://i66.tinypic.com/2q9e1vs.png)
https://www.swg.usace.army.mil/Portals/26/docs/Navigation/Channel_Survey_Maps/HS/MLLW/HS_07_BGB_20181006_CS_EX_41_MLLW_68000_83305.pdf (https://www.swg.usace.army.mil/Portals/26/docs/Navigation/Channel_Survey_Maps/HS/MLLW/HS_07_BGB_20181006_CS_EX_41_MLLW_68000_83305.pdf)
It is not silted up and it is maintained at these depths and widths.
What do you imagine with the information I have shared with you could be done in the channel to significantly improve? And keep in mind the tunnel project is to get the water to the Houston Ship Channel, not replace it.
Outside the channel to near the banks is highly sedimented. Removal of those sludges would give additonal upstream storm flush capacity (removal of solids displacing volume, bottlenecking flow) . Back in '92 ECHMA ran the numbers, and thought though not cost effective, would be a way to eleviate some areas of Houston flooding.
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Save Buffalo Bayou
A Ribbon of Life Through the Concrete of Houston
Flood Control’s Destructive Bayou Maintenance Will Lead to More Erosion, More Maintenance
Practices Fall Behind Standards Elsewhere
June 3, 2018
http://www.savebuffalobayou.org/?page_id=5324 (http://www.savebuffalobayou.org/?page_id=5324)
For months we have been receiving complaints about the damage the Harris County Flood Control District is doing to Buffalo Bayou.
Citizens have been sending us video and photographs of contract workers dredging, banging, mucking, bulldozing, slamming and damming the channel and banks; dragging, cutting, and removing large trees, live trees, trees fallen against the banks, trees fallen in the woods.
And now we have reports that they’ve done the same to Cypress Creek in northern Harris County.
The “maintenance†they have done – virtually clearing out the channel and banks — will lead to greater erosion and instability, more sediment and more flooding. And more costly maintenance.
Harvey and the flooding that followed left a huge amount of woody and other sorts of debris in our bayous, our natural drainage system. Buffalo Bayou, our main river, flows from its source in the Katy Prairie for some 53 miles east through the center of Houston, becoming the Houston Ship Channel and emptying into Galveston Bay. For much of that route, the 18,000-year-old bayou remains one of the few relatively natural streams in the city. It accumulated a lot of debris, logjams and snags during Harvey, as did Cypress Creek.
The Importance of Fallen Trees
There are trees along Buffalo Bayou, great tall trees in places, and they sometimes fall into it. Trees have been doing this on rivers for over a hundred million years. Trees, before and after they fall, are a crucial part of the river’s natural system. Overhanging trees shade the water, regulating the temperature. Their extensive roots, together with the roots of riparian plants, anchor the bank, protecting the bank from washing out. When trees fall into the channel, they continue to provide stability to the stream and its banks, trapping sediment, fortifying against and deflecting heavy flows, helping the channel to maintain a healthy width and depth and to form riffles and pools, helping the stream to restore itself more quickly after a flood, and providing food and habitat for the diversity of creatures large and small that sustain the bayou’s ecosystem.
Without trees on and in the bayou, the bayou would become a barren, shifting, sandy wasteland, much more prone to washouts and collapsing banks, unable to stabilize and restore itself, sending increasing amounts of sediment (and trash) downstream. Alarmingly, some scientists maintain that once the trees are gone, as trees on our urban streams continue to be cut down, they cannot be replaced, and their vital function is lost forever. (pp. 12-13)
Both Buffalo Bayou and Cypress Creek experienced severe flooding as a result of Harvey, for a variety of reasons, though Cypress Creek floods more regularly. Removal or repositioning of some large woody debris that blocks the flow is necessary for what flood managers call “conveyance†as well as recreational paddling. But there are right ways and wrong ways of doing it.
In the past, the practice of natural resource and flood control managers was to remove all large woody debris to improve stream flow or conveyance. But that began to change in the Seventies with the recognition of the importance of fallen trees. Now the practice around the country is not just to leave strategically positioned logs in streams but actually to put them there, even saving large logs for that purpose. (p. 7)
More at link above.
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https://m.chron.com/neighborhood/spring/news/article/Tunnels-could-be-a-viable-solution-to-flooding-in-14366255.php (https://m.chron.com/neighborhood/spring/news/article/Tunnels-could-be-a-viable-solution-to-flooding-in-14366255.php)
Brian Gettinger, engineer and tunneling services lead with engineering consulting firm Freese and Nichols, gave a presentation on the viability of tunnels as a solution for the flooding issues plaguing Houston. The event was held at the Northgate Country Club as part of the Houston Northwest Chamber of Commerce Community Luncheon on Aug. 15.
Gettinger stressed that the projects are currently being studied and no plans for tunnel design or construction have been finalized. However, he said that tunnels could reduce the impact of major rain events on communities and land by directing water underground and pushing it to the Houston Ship Channel.
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This seems the same as simply widening the bayous to accommodate more water.
Which means if the bayous or tunnels get overloaded with excess, there is even more water sitting around to cause havoc.
New Orleans has its Lake Pontchartrain next to it and Houston will soon have its tunnels....