We all understand intellectually that vegetation helps reduce runoff. But I never fully appreciated how MUCH runoff it could prevent until I saw this video. Michael Jrab sent the link to me this morning. It shows a brilliantly simple, table-top experiment in a science class. The experiment dramatizes the value of vegetation and how clearcutting can contribute to flooding by accelerating the rate of runoff.
It takes only a minute or so to watch. Notice both the volume AND THE CLARITY of the water coming out.
Now contrast that with this shot of erosion in the clearcut area just north of Elm Grove. One can only wonder how fast the water moved through here.
Part of the 262 acres clearcut by Figure Four Partners, LTD, a subsidiary of PSWA and Perry Homes.
Posted by Bob Rehak on 5/13/2019
622 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/05/ClearCut-Demo.jpg?fit=964%2C1500&ssl=11500964adminadmin2019-05-13 15:56:052019-05-13 22:21:47Simple Demonstration Underscores How Clearcutting Contributes to Flooding
Edy and Ricky Cogdill live across the street from Abel Vera on Village Springs Drive. Both the Veras and the Cogdills live at the end of the street. Their properties butts up against the new development on the other side of the Montgomery County line seen in the background of this video. Edy Cogdill shot the video on May 7, 2019. It shows what hydrologists call “overland sheet flow.”
A small part of the 262-acre development that drains toward Elm Grove. Sheet flow from this clear-cut area ran off into Elm Grove. On top of street flooding, it caused house flooding.
Edy Cogdill shot this video will standing on her front porch with an umbrella. As the floodwaters came out of the clear-cut area to their north, the water hit the Cogdill house and started moving sideways. Toward the end of this short video, Edy pans right. You can see the the flow coming out of the new development and rushing down Village Springs Drive past the dead-end barrier.
The water from the development added to street flooding in progress. As a result, homes flooded.
Video courtesy of Edy and Ricky Cogdill on Village Springs Drive in Elm Grove. Shot on May 7, 2019.
Harris County Flood Control Issues Report on Storm
The report says: “130 structures were flooded in the Elm Groove Village subdivision in the northern portions of Kingwood on Tuesday evening. HCFCD staff investigated this area on Wednesday, May 8th and determined that the flooding was potentially caused by development upstream in Montgomery County that sent large volumes of sheetflow into the subdivision and Taylor Gully (G103-80-03.1). The isolated nature of the heavy rainfall on Tuesday afternoon prevented more widespread flooding impacts.”
Lindner also cautioned that the number of affected structures may change; the City of Houston is still verifying the number. Earlier media reports of 400 homes flooding may have overstated the problem.
2- to 50-Year Official Rainfall Rates
The Harris County Flood Control Report on the storm also states that on May 7: “Heavy rainfall rates developed due to slow storm motions over northeast Harris County including the Humble and Kingwood areas. A 30-min rate of 2.9 inches was recorded at US 59 and the West Fork of the San Jacinto River and a 1 hour rate of 4.0 inches. A 6-hr rainfall rate of 7.9 inches was recorded at the East Fork of the San Jacinto River and FM 1485. Rainfall rates between the 15-min and 6- hr time periods on Tuesday afternoon and evening averaged between a 2-yr and 50-yr frequency over the extreme northeast portions of Harris into southeast Montgomery Counties. This rainfall was relatively isolated in the far northeast portions of Harris County and the Kingwood area.”
Posted by Bob Rehak on 5/13/2019
622 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2019/05/VillageSpingsKeyframe.jpg?fit=900%2C1365&ssl=11365900adminadmin2019-05-13 12:21:322019-05-13 12:50:35Cogdill Video Shows Overland Sheet Flow From Clear-Cut Area Pouring into Elm Grove; HCFCD Issues Report on Flood
As I interviewed flood victims in Elm Grove last week, I constantly heard different versions of the same story. “We never flooded before. Then they changed the drainage on that land to the north of us and we flooded.” Another common theme: “Water was flowing right out of the new subdivision through our street.”
“You Can’t Flood Neighbors”
An acquaintance at Harris County Flood Control told me that its a basic tenet of Texas law that you can’t flood your neighbors. I asked him for a legal reference. He said, “Check the Texas State Water Code.” I did. It’s more than 2200 pages long. Just as I was falling asleep reading the requirements for inter-basin transfers, I stumbled on Sec. 11.086. Quite interesting, that section! It reads (in part):
“OVERFLOW CAUSED BY DIVERSION OF WATER”
(a) No person may divert or impound the natural flow of surface waters in this state, or permit a diversion or impounding by him to continue, in a manner that damages the property of another by the overflow of the water diverted or impounded.
(b) A person whose property is injured by an overflow of water caused by an unlawful diversion or impounding has remedies at law and in equity and may recover damages occasioned by the overflow.
(c) The prohibition of Subsection (a) of this section does not in any way affect the construction and maintenance of levees and other improvements to control floods, overflows, and freshets in rivers, creeks, and streams or the construction of canals for conveying water for irrigation or other purposes authorized by this code. However, this subsection does not authorize any person to construct a canal, lateral canal, or ditch that obstructs a river, creek, bayou, gully, slough, ditch, or other well-defined natural drainage.
(d) (Not applicable to Elm Grove)
Amended by Acts 1977, 65th Leg., p. 2207, ch. 870, Sec. 1, eff. Sept. 1, 1977.
In Plain Language
I’m not a lawyer and I don’t offer legal advice, but it sounds to me as if the law says:
(a) You can’t divert water in a way that damages others.
(b) Someone whose property is harmed by an overflow may recover damages.
(c) People (such as developers) can make improvements in drainage to control flooding. However, they can’t make improvements that obstruct well-defined natural drainage features such as creeks, gullies or ditches.
That last point is crucial because the developer north of Elm Grove (Figure Four Partners, LTD), reportedly filled in natural ditches or streams that worked well for generations. The replacements? Those didn’t work out so well in heavy rains last week.
A Photographic Examination of Flood Pathways
Abel Vera, the resident closest to the new development on Village Springs Drive was flooded from the street, not Taylor Gully. How can you be sure? Compare these two pictures on the inside and outside of the fence between his house and Taylor Gully.
Inside back yard fence, facing Village Springs Drive. Taylor Gully is on the other side.Photo taken on 4/8/19, two days after flood.Outside of same fence facing gully shows no debris line. Grass is standing tall, not matted down by flood waters. These two photos in combination suggest that the primary direction of flow came from the street, not the drainage ditch.Warning sign at end of Village Springs Drive caught flood debris rushing down the street from developer’s property. This was not just a case of water backing up from storm drains.Vera’s vehicle was parked high on his driveway. This side faced water flowing out of the new development. The side facing away from the new development did not trap any debris. This indicates flow came from the new development. The flood was not simply from water rising in the street. It was from water flowing from the developer’s property where changes to drainage had been made.Vera’s house is behind the trees on the right. Notice how much higher the developer’s new culvert is compared to the land around it. The height and the constriction diverted water toward Vera’s house on the right behind the trees and down Village Springs Drive.
Where Did The Water Come From?
I believe the floodwater came from rainfall on approximately 267 acres being clear cut by the developer. Had a foot of rain fallen on Vera’s property, with none coming from anywhere else, the water level would not have risen past the bottom of his driveway. His home would likely be whole today.
However, clear cutting, filling in old channels, constricting new channels and changing the slope of the land on those 267 acres all appear to have diverted water. Below is a satellite image showing the outlines of the developer’s property.
Approximate outline of land owned by Figure Four Partners LTD. This satellite image is dated 2/23/19. More land has been clear cut since then.
Let’s zoom in on the area above the culvert where the drainage ditch coming down the east side of the property makes a 120-degree turn, just above Same Way and Right Way.
Use the image below to understand the location of the images that follow.
The photo below compared to the satellite image above shows that the developer appears to have extended the ditch straight up. However, the ditch extension also appears to be clogged with debris from the clear cutting. Whether the developer stacked it there or the storm swept it there is unknown.
Facing north.The main ditch makes a 120-degree turn by the tire. You can see what appears to be a new ditch that helps drain the northern section of landin the upper right. Here’s a telephoto shot showing the same blockage in the ditch.Immediately to the left of the shot above, you can see how far clear cutting has progressed toward the ditch.Turning 180 degrees and looking the other way down the ditch, toward Taylor Gully, you can see that it dead-ends halfway down the eastern boundary of the property.At the end of the shot above, this is what you find. The entire flow of the ditch must go through what appears to be a 2-foot pipe covered with debris..
Compared to the volume of the ditch, that two-foot pipe will not carry much water in a flood. It may have been adequate when surrounded by woodlands and wetlands to sponge up any overflow. Right now though, it doesn’t feel up to the task of draining hundreds of acres of clear-cut land.
Shot while standing on edge of ditch above the pipe entrance, looking south and a little west. When water came out of the ditch above, it headed back west toward the Vera House on Village Springs Drive to find another way out.
Here you can see the force of large volume of water came out of the ditch above the pipe during the flood.
Consequences
This sequence of pictures suggests that a large volume of water coming down from the clear-cut parcel to the north, wound up being channeled back across the southern parcel and into Elm Grove. A portion of the flood also channeled through the subdivision to the east. Restrictions in both outflow channels forced water into streets and homes.
Here’s what Abel Vera’s home looked like yesterday.
There are 400 more just like it in Elm Grove.
Posted by Bob Rehak on 5/13/2019
622 Days since Hurricane Harvey
All thoughts above are opinions regarding matters of public policy 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/2019/05/ElmGroveFlood_01_08-1.jpg?fit=1500%2C1000&ssl=110001500adminadmin2019-05-13 00:37:382019-05-13 01:52:43Law on “Overflow Caused by Diversion of Water” and Photographic Analysis of Recent Elm Grove Flood
Simple Demonstration Underscores How Clearcutting Contributes to Flooding
We all understand intellectually that vegetation helps reduce runoff. But I never fully appreciated how MUCH runoff it could prevent until I saw this video. Michael Jrab sent the link to me this morning. It shows a brilliantly simple, table-top experiment in a science class. The experiment dramatizes the value of vegetation and how clearcutting can contribute to flooding by accelerating the rate of runoff.
It takes only a minute or so to watch. Notice both the volume AND THE CLARITY of the water coming out.
Now contrast that with this shot of erosion in the clearcut area just north of Elm Grove. One can only wonder how fast the water moved through here.
Posted by Bob Rehak on 5/13/2019
622 Days since Hurricane Harvey
Cogdill Video Shows Overland Sheet Flow From Clear-Cut Area Pouring into Elm Grove; HCFCD Issues Report on Flood
Edy and Ricky Cogdill live across the street from Abel Vera on Village Springs Drive. Both the Veras and the Cogdills live at the end of the street. Their properties butts up against the new development on the other side of the Montgomery County line seen in the background of this video. Edy Cogdill shot the video on May 7, 2019. It shows what hydrologists call “overland sheet flow.”
Edy Cogdill shot this video will standing on her front porch with an umbrella. As the floodwaters came out of the clear-cut area to their north, the water hit the Cogdill house and started moving sideways. Toward the end of this short video, Edy pans right. You can see the the flow coming out of the new development and rushing down Village Springs Drive past the dead-end barrier.
Harris County Flood Control Issues Report on Storm
Jeff Lindner of Harris County Flood Control issued a report this morning on last week‘s two flash flooding events.
The report says: “130 structures were flooded in the Elm Groove Village subdivision in the northern portions of Kingwood on Tuesday evening. HCFCD staff investigated this area on Wednesday, May 8th and determined that the flooding was potentially caused by development upstream in Montgomery County that sent large volumes of sheetflow into the subdivision and Taylor Gully (G103-80-03.1). The isolated nature of the heavy rainfall on Tuesday afternoon prevented more widespread flooding impacts.”
Lindner also cautioned that the number of affected structures may change; the City of Houston is still verifying the number. Earlier media reports of 400 homes flooding may have overstated the problem.
2- to 50-Year Official Rainfall Rates
The Harris County Flood Control Report on the storm also states that on May 7: “Heavy rainfall rates developed due to slow storm motions over northeast Harris County including the Humble and Kingwood areas. A 30-min rate of 2.9 inches was recorded at US 59 and the West Fork of the San Jacinto River and a 1 hour rate of 4.0 inches. A 6-hr rainfall rate of 7.9 inches was recorded at the East Fork of the San Jacinto River and FM 1485. Rainfall rates between the 15-min and 6- hr time periods on Tuesday afternoon and evening averaged between a 2-yr and 50-yr frequency over the extreme northeast portions of Harris into southeast Montgomery Counties. This rainfall was relatively isolated in the far northeast portions of Harris County and the Kingwood area.”
Posted by Bob Rehak on 5/13/2019
622 Days since Hurricane Harvey
Law on “Overflow Caused by Diversion of Water” and Photographic Analysis of Recent Elm Grove Flood
As I interviewed flood victims in Elm Grove last week, I constantly heard different versions of the same story. “We never flooded before. Then they changed the drainage on that land to the north of us and we flooded.” Another common theme: “Water was flowing right out of the new subdivision through our street.”
“You Can’t Flood Neighbors”
An acquaintance at Harris County Flood Control told me that its a basic tenet of Texas law that you can’t flood your neighbors. I asked him for a legal reference. He said, “Check the Texas State Water Code.” I did. It’s more than 2200 pages long. Just as I was falling asleep reading the requirements for inter-basin transfers, I stumbled on Sec. 11.086. Quite interesting, that section! It reads (in part):
“OVERFLOW CAUSED BY DIVERSION OF WATER”
(a) No person may divert or impound the natural flow of surface waters in this state, or permit a diversion or impounding by him to continue, in a manner that damages the property of another by the overflow of the water diverted or impounded.
(b) A person whose property is injured by an overflow of water caused by an unlawful diversion or impounding has remedies at law and in equity and may recover damages occasioned by the overflow.
(c) The prohibition of Subsection (a) of this section does not in any way affect the construction and maintenance of levees and other improvements to control floods, overflows, and freshets in rivers, creeks, and streams or the construction of canals for conveying water for irrigation or other purposes authorized by this code. However, this subsection does not authorize any person to construct a canal, lateral canal, or ditch that obstructs a river, creek, bayou, gully, slough, ditch, or other well-defined natural drainage.
(d) (Not applicable to Elm Grove)
Amended by Acts 1977, 65th Leg., p. 2207, ch. 870, Sec. 1, eff. Sept. 1, 1977.
In Plain Language
I’m not a lawyer and I don’t offer legal advice, but it sounds to me as if the law says:
(a) You can’t divert water in a way that damages others.
(b) Someone whose property is harmed by an overflow may recover damages.
(c) People (such as developers) can make improvements in drainage to control flooding. However, they can’t make improvements that obstruct well-defined natural drainage features such as creeks, gullies or ditches.
A Photographic Examination of Flood Pathways
Abel Vera, the resident closest to the new development on Village Springs Drive was flooded from the street, not Taylor Gully. How can you be sure? Compare these two pictures on the inside and outside of the fence between his house and Taylor Gully.
Where Did The Water Come From?
I believe the floodwater came from rainfall on approximately 267 acres being clear cut by the developer. Had a foot of rain fallen on Vera’s property, with none coming from anywhere else, the water level would not have risen past the bottom of his driveway. His home would likely be whole today.
However, clear cutting, filling in old channels, constricting new channels and changing the slope of the land on those 267 acres all appear to have diverted water. Below is a satellite image showing the outlines of the developer’s property.
Let’s zoom in on the area above the culvert where the drainage ditch coming down the east side of the property makes a 120-degree turn, just above Same Way and Right Way.
Use the image below to understand the location of the images that follow.
The photo below compared to the satellite image above shows that the developer appears to have extended the ditch straight up. However, the ditch extension also appears to be clogged with debris from the clear cutting. Whether the developer stacked it there or the storm swept it there is unknown.
Compared to the volume of the ditch, that two-foot pipe will not carry much water in a flood. It may have been adequate when surrounded by woodlands and wetlands to sponge up any overflow. Right now though, it doesn’t feel up to the task of draining hundreds of acres of clear-cut land.
Consequences
This sequence of pictures suggests that a large volume of water coming down from the clear-cut parcel to the north, wound up being channeled back across the southern parcel and into Elm Grove. A portion of the flood also channeled through the subdivision to the east. Restrictions in both outflow channels forced water into streets and homes.
Here’s what Abel Vera’s home looked like yesterday.
Posted by Bob Rehak on 5/13/2019
622 Days since Hurricane Harvey
All thoughts above are opinions regarding matters of public policy and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP statute of the great State of Texas.