Have you ever flown over a winding river and wondered why rivers move? Why do they wander across the landscape and evolve the way they do? The lower Mississippi River and its delta form a spectacular example. But others are all around us.
Take, for instance, the Trinity River where it enters Galveston Bay. Or look on any map. You will likely see landscapes carved by rivers that leave evidence of their former paths behind.
But why do rivers change course? The brilliantly simple YouTube Video by Practical Engineering below describes the basics of “fluvial geomorphology.” That fancy phrase describes the science behind the shape of rivers.
Fisk produced gorgeous historical maps of the river snaking across miles of river valley.
Screen capture of historical river maps by Harold Fisk shown in Why Rivers Move by Practical Engineering Video.
A decade later, Emory Lane, a civil engineer and hydrologist at Colorado State University, went on to develop a unified theory of sediment transport. His theory explains the movement and shape of such rivers in an “equation” that uses just four variables:
Quantity of sediment carried by the water
Median sediment size
Quantity of water
Slope of the landscape (length divided by elevation change)
Lane’s “equation” looks like this.
Screen capture of Lane’s equation from Why Rivers Move by Practical Engineering.
That funny symbol in the middle means ‘is proportional to.’ Scientists use it to show something that varies in relation to something else.
If you change one variable, one or more other variables change to bring the river back to its “normal” state. Scientists and engineers still use this formula today.
It means that in a stable stream, the flow of water multiplied by the slope is proportional to the amount of sediment being transported times the size of that sediment. (But don’t let that scare you!)
From Stream-Table Models to Real World
In the abstract, that may be a lot for average people to wrap their heads around. So the video uses a “stream table” and balance-scale model to illustrate what happens when you change each variable. They bring the formula to life and make it easy to understand. For example…
More water (say, in a flood) can move more and larger sediment. So, the banks of a river erode.
This can threaten roads, pipelines, and property. The eventual deposition of all that sediment can also choke a channel and contribute to flooding. Or fill up reservoirs and reduce water supply.
Sound familiar? All those things happened in the Lake Houston area.
To restore balance, the river changes its slope by increasing its length. This explains the meanders found in most rivers in this region. A meandering river wanders back and forth across the landscape like a snake instead of making a straight line through it.
Wherever slight bends occur, the river scours the outside of the curve (called the cut bank). That’s because the water moves faster on the outside of a curve. The river then deposits larger particles of sediment on inside curves farther downriver (called point bars) where water moves slower.
Eventually these curves in a river become so exaggerated, that they cut themselves off, leaving oxbow lakes behind.
Screen capture of meandering river and oxbow lakes from Practical Engineering video.
This National Park Service page contains an excellent series of illustrations that show the evolution of meanders over time plus their migration across the landscape.
Lane’s equation predicts that there’s no such thing as a stable river. All rivers change all the time in response floods, drought, development, dams, sand mining, farming and more.
When Natural Systems Lose Balance…
At every point along a river or stream, erosion and deposition are constantly balancing each other.
But Lane’s equation can’t predict exactly where or when a river will move. Nor can it predict the rate of change. The Practical Engineering video points out that the rate and volume of change depend on other factors not in the equation, such as vegetation and the “pulsing” of flows as you might see downstream of a dam like the one on Lake Conroe.
The screen capture below shows what happened in models comparing a steady flow and a pulsed flow.
Screen capture shows erosion differences between steady flow (left) and pulsed flows (right) using the same volume of water.
The pulsed flow creates much more erosion and faster movement of channels. And that has many real world implications.
Who Should Watch This Video?
This 16-minute video is a real eye opener for a variety of audiences. It’s suitable for students from late middle school and up. You don’t need to be a math or science whiz to understand it. Its power is its simplicity.
Among students, the video may stimulate curiosity in earth sciences, engineering, math, economics, history and urban planning. And for adults, it shows how four variables tie them all together.
It makes a great tutorial for policy makers struggling with issues such as setbacks from rivers for homes and businesses.
In addition, everyone who lives near or is considering buying property near a river, stream or channel should view this.
The producers say the next video in the Why-Rivers-Move series will show how human changes affect the flow of rivers. Can’t wait!
My thanks to Dr. Matthew Berg, CEO of Simfero Consultants for bringing this to my attention.
GLO Commissioner Dawn Buckingham, M.D., announced yesterday more than $43 million in HUD grants for 44 infrastructure projects stemming from 2019 Disasters. The $43 million is the combined total of grants made to counties and cities stretching from the Rio Grande Valley to southeast Texas.
Counties where 2019 community development block grant disaster-relief (CDBG-DR) money will be distributed for infrastructure projects.
The infrastructure-project grants will help communities recover from the 2019 South Texas Floods as well as Tropical Storm Imelda, which devastated SE Texas.
List of Recipients
The funds will be used to improve streets as well as water and drainage facilities in:
Counties:
Cameron
Chambers
Harris
Hidalgo
Jefferson
Liberty
Montgomery
Orange
San Jacinto
Willacy
Cities
Beaumont
China
Combes
Daisetta
La Feria
La Villa
Laguna Vista
Liberty
Mercedes
Mission
Nome
Old River-Winfree
Orange
Palmview
Pasadena
Pine Forest
Pinehurst
Plum Grove
Port Arthur
Port Isabel
Primera
Rio Hondo
Santa Rosa
Splendora
Vidor
West Orange
Woodloch
“Here to Help”
“Consecutive disasters have devastated communities in the Lower Rio Grande Valley and Southeast Texas, but the Texas General Land Office is here to help,” said Commissioner Buckingham. “These critical infrastructure awards will divert floodwaters away from homes, increase the resiliency of communities to respond to natural disasters, and restore peace of mind when the next storm hits.”
Out of the $227.5 million, GLO allocated $61,430,000 in disaster recovery funds for infrastructure projects. They will assist disaster relief, long-term recovery, and restoration of infrastructure for local communities. The rest of $227 million was allocated to grants that help individuals recover.
GLO announced the opening of the application for eligible counties and cities on March 15, 2022. Applications closed on August 1, 2022. Each applicant was eligible to submit a total of two applications. All activities had to contribute to the long-term recovery and restoration of infrastructure.
The GLO recognizes that repair and enhancements of local infrastructure are crucial components of long-term recovery and viability of communities.
Tropical Storm Imelda released an unprecedented 3-day total rainfall amount of 28 inches on Plum Grove. That limited the city’s ability to provide an immediate response due to the inundation of flood water. As a result, this project will provide much-needed drainage improvements within Orange Branch Creek which is located in the middle of the city and runs from the northeast down to the southeast. The project will install culverts and restore roads.
Splendora Lift Station Drainage Improvements – $596,625
Imelda flooding submerged the Pinewood Lift Station site, as well as its emergency generator and electrical switchgear located at the northern intersection of Pinewood Drive and First Street. Loss of both primary and emergency back-up power led to a sanitary sewer overflow at Pinewood lift station. Vehicular access, including emergency vehicle access, was not possible because of the depth of flooding in the area. This project includes drainage and generator improvements at the Pinewood Lift Station.
Construction will include the following activities:
Regrade ditch and install double headwalls
Install reinforced concrete pipe culverts under First Street with road restoration and ditch regrading
Install new natural gas generator and automatic transfer switch
Install an elevated metal platform, staircase and skid for generator
Liberty Water, Sewer Improvements – $1,000,000
The project will provide for water and sewer line improvements located within the eastern side of the city along Beaumont Road, Minglewood Road, Glenn Street and Tanner Street. These should reduce overflow concerns for residents and businesses along these streets. The project will make improvements to sewer lines and water lines and remove and replace existing lift stations with gravity sanitary sewer lines.
Descriptions of Other Grants
For a full description of other grants in this batch, see the GLO website.
Posted by Bob Rehak on 3/22/2023 based on information from the Texas General Land Office
2031 Days since Hurricane Harveyand 1280 Days since Imelda
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/08/Screen-Shot-2020-08-03-at-5.55.45-PM.png?fit=846%2C780&ssl=1780846adminadmin2023-03-22 12:42:192023-03-22 12:50:55Plum Grove, Splendora, Liberty, Others Receive HUD Grants Through GLO
The Texas Water Development Board (TWDB) is soliciting feedback on its proposed scoring matrix to rank efforts for the state’s first flood plan. Each region has submitted proposed projects. The scoring matrix will help rank order them statewide. And the deadline is April Fools’ Day.
TWDB has provided several spreadsheets that show how the criteria and weights would affect ranking of sample projects. But understand that TWDB is only soliciting comments on scoring criteria and their weights at this time, not the rankings of the limited sample. All this is DRAFT data, not final recommendations.
39 Factors in Three Different Categories and Three Groups
TWDB has proposed weighing the relative merits of 39 factors that span three categories with benefits in three more groups:
Flood Management Evaluations (Studies)
Flood Mitigation Projects
Flood Management Strategies
TWDB uses three types of factors:
Flood risk
Risk reduction
Other related factors
“Other” includes such factors as cost and environmental benefits.
The 39 factors include:
Emergency Need (Y/N)
Estimated number of structures at 100yr flood risk
Residential structures at 100-year flood risk
Estimated Population at 100-year flood risk
Critical facilities at 100-year flood risk (#)
Number of low water crossings at flood risk (#)
Estimated number of road closures (#)
Estimated length of roads at 100-year flood risk (Miles)
Estimated farm & ranch land at 100-year flood risk (acres)
Number of structures with reduced 100yr (1% annual chance) Floodplain
Number of structures removed from 100yr (1% annual chance) Floodplain
Percent of structures removed from 100yr (1% annual chance) Floodplain (Calculated by TWDB from reported data)
Residential structures removed from 100yr (1% annual chance) Floodplain
Estimated Population removed from 100yr (1% annual chance) Floodplain
Critical facilities removed from 100yr (1% annual chance) Floodplain (#)
Number of low water crossings removed from 100yr (1% annual chance) Floodplain (#)
Estimated reduction in road closure occurrences
Estimated length of roads removed from 100yr floodplain (Miles)
Estimated farm & ranch land removed from 100yr floodplain (acres)
Cost per structure removed from 100-year floodplain
Percent Nature-based Solution (by cost)
Benefit-Cost Ratio
Water Supply Benefit (Y/N)
Severity – Pre-Project Average Depth of Flooding (100-year)
Severity – Community Need (% Population)
Flood Risk Reduction
Flood Damage Reduction
Critical Facilities Damage Reduction
Life and Safety
Water Supply
Social Vulnerability
Nature-Based Solution
Multiple Benefits
Operations and Maintenance Costs
Admin, Regulatory Obstacles
Environmental Benefit
Environmental Impact
Mobility
Regional
Factors (in Risk, Risk Reduction and Other groups) may receive weight in one, two or all three main categories (Evaluations, Projects, Strategies).
Intent: Consistency Across All Regions Statewide
The intent of the TWDB ranking method for the state flood plan is to provide a consistent approach to be used across all Texas regions. The goal: to systematically address the flood hazards with most population, properties and critical facilities at risk in the state during a 1% annual chance flood.
TWDB bases all risk on 1% annual chance/100-year flood estimates.
Areas with widely varying measurements such as population will have answers normalized. Basically, this means adjusting widely varying scales to a common scale (such as 0 to 1) to facilitate comparison.
More Background, Sample Data, Providing Feedback
All relevant ranking workbooks, documents, and the link to the online survey tool are available on the State Flood Planning webpage.
The deadline to submit feedback is Saturday, April 1, 2023.
Importance of Feedback
We have seen how seriously the weights given to such rankings can skew priorities. Consider, for instance, the Equity Prioritization Framework adopted after the fact by a Harris County Judge and two commissioners for proposed 2018 Flood Bond Projects (unrelated to these projects).
So, if you have reservations with the TWDB scoring system, register your complaints NOW. My biggest concerns are that it’s hard to understand. It also contains broken links and typos that get in the way of understanding.
But understanding is critical. Many of the flood-reduction projects needed on the periphery of Harris County will need be addressed by state money. That’s because 10 of our 23 watersheds originate outside the County. I guess that would fall under #39 Regional. But…
The proposed scoring matrix gives ZERO weight to Regional benefits.
That’s kind of strange for a regional plan designed to encourage solutions that cross jurisdictions. Scoring matrix penalizes people on the periphery of large urban areas like Harris County.
I’ve already sent my feedback on that one.
Inconsistencies? TWDB refers to FMS as Flood Management Strategy on its spreadsheet and Flood Management Solution in introductory text.
Another example: In its spreadsheets, footnotes describing the listing of criteria do not correspond in all cases to the criteria listed. Nor does a link work to a supposed explanation of the criteria.
And there’s no description that I could find of how all these categories, measurements and groups fit together.
Finally, it’s not clear how they will treat areas that have a 50% annual chance of flooding (2-year flood). We’ve seen in highly urbanized areas that – after spending hundreds of millions of dollars in some watersheds – the best we can do achieve in some areas is a 25-year level of service. Achieving better would require buying out thousands of homes. What will happen in such cases?
Please make the effort to provide public feedback.
Posted by Bob Rehak on 3/20/2023
2029 Days since Harris County
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.
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/2018/05/Watersheds-802x900.jpg?fit=802%2C900&ssl=1900802adminadmin2023-03-20 14:43:042023-03-21 15:10:08TWDB Needs Feedback on Ranking Method for State Flood Plan
Why Rivers Move
Have you ever flown over a winding river and wondered why rivers move? Why do they wander across the landscape and evolve the way they do? The lower Mississippi River and its delta form a spectacular example. But others are all around us.
Take, for instance, the Trinity River where it enters Galveston Bay. Or look on any map. You will likely see landscapes carved by rivers that leave evidence of their former paths behind.
But why do rivers change course? The brilliantly simple YouTube Video by Practical Engineering below describes the basics of “fluvial geomorphology.” That fancy phrase describes the science behind the shape of rivers.
The Mathematics of Geological Change
Back in 1944, a geologist named Harold Fisk, Ph.D., then a professor at Louisiana State, produced a report for the Army Corps of Engineers called “Geological Investigation of the Alluvial Valley of the Lower Mississippi River.”
Fisk produced gorgeous historical maps of the river snaking across miles of river valley.
A decade later, Emory Lane, a civil engineer and hydrologist at Colorado State University, went on to develop a unified theory of sediment transport. His theory explains the movement and shape of such rivers in an “equation” that uses just four variables:
Lane’s “equation” looks like this.
That funny symbol in the middle means ‘is proportional to.’ Scientists use it to show something that varies in relation to something else.
If you change one variable, one or more other variables change to bring the river back to its “normal” state. Scientists and engineers still use this formula today.
It means that in a stable stream, the flow of water multiplied by the slope is proportional to the amount of sediment being transported times the size of that sediment. (But don’t let that scare you!)
From Stream-Table Models to Real World
In the abstract, that may be a lot for average people to wrap their heads around. So the video uses a “stream table” and balance-scale model to illustrate what happens when you change each variable. They bring the formula to life and make it easy to understand. For example…
This can threaten roads, pipelines, and property. The eventual deposition of all that sediment can also choke a channel and contribute to flooding. Or fill up reservoirs and reduce water supply.
Sound familiar? All those things happened in the Lake Houston area.
To restore balance, the river changes its slope by increasing its length. This explains the meanders found in most rivers in this region. A meandering river wanders back and forth across the landscape like a snake instead of making a straight line through it.
Wherever slight bends occur, the river scours the outside of the curve (called the cut bank). That’s because the water moves faster on the outside of a curve. The river then deposits larger particles of sediment on inside curves farther downriver (called point bars) where water moves slower.
Eventually these curves in a river become so exaggerated, that they cut themselves off, leaving oxbow lakes behind.
This National Park Service page contains an excellent series of illustrations that show the evolution of meanders over time plus their migration across the landscape.
Lane’s equation predicts that there’s no such thing as a stable river. All rivers change all the time in response floods, drought, development, dams, sand mining, farming and more.
When Natural Systems Lose Balance…
At every point along a river or stream, erosion and deposition are constantly balancing each other.
But Lane’s equation can’t predict exactly where or when a river will move. Nor can it predict the rate of change. The Practical Engineering video points out that the rate and volume of change depend on other factors not in the equation, such as vegetation and the “pulsing” of flows as you might see downstream of a dam like the one on Lake Conroe.
The screen capture below shows what happened in models comparing a steady flow and a pulsed flow.
The pulsed flow creates much more erosion and faster movement of channels. And that has many real world implications.
Who Should Watch This Video?
This 16-minute video is a real eye opener for a variety of audiences. It’s suitable for students from late middle school and up. You don’t need to be a math or science whiz to understand it. Its power is its simplicity.
Among students, the video may stimulate curiosity in earth sciences, engineering, math, economics, history and urban planning. And for adults, it shows how four variables tie them all together.
It makes a great tutorial for policy makers struggling with issues such as setbacks from rivers for homes and businesses.
In addition, everyone who lives near or is considering buying property near a river, stream or channel should view this.
The producers say the next video in the Why-Rivers-Move series will show how human changes affect the flow of rivers. Can’t wait!
My thanks to Dr. Matthew Berg, CEO of Simfero Consultants for bringing this to my attention.
Posted by Bob Rehak on 3/24/23
2033 Days since Hurricane Harvey
Plum Grove, Splendora, Liberty, Others Receive HUD Grants Through GLO
GLO Commissioner Dawn Buckingham, M.D., announced yesterday more than $43 million in HUD grants for 44 infrastructure projects stemming from 2019 Disasters. The $43 million is the combined total of grants made to counties and cities stretching from the Rio Grande Valley to southeast Texas.
The infrastructure-project grants will help communities recover from the 2019 South Texas Floods as well as Tropical Storm Imelda, which devastated SE Texas.
List of Recipients
The funds will be used to improve streets as well as water and drainage facilities in:
“Here to Help”
“Consecutive disasters have devastated communities in the Lower Rio Grande Valley and Southeast Texas, but the Texas General Land Office is here to help,” said Commissioner Buckingham. “These critical infrastructure awards will divert floodwaters away from homes, increase the resiliency of communities to respond to natural disasters, and restore peace of mind when the next storm hits.”
Texas GLO 2019 Disaster-Recovery Funds
The Texas General Land Office (GLO) is administering $227,510,000 in Community Development Block Grant Disaster Recovery (CDBG-DR) funds from the U.S. Department of Housing and Urban Development (HUD) related to 2019 flooding. This is separate from the $750 million in mitigation funding related to Harvey and Harris County.
Out of the $227.5 million, GLO allocated $61,430,000 in disaster recovery funds for infrastructure projects. They will assist disaster relief, long-term recovery, and restoration of infrastructure for local communities. The rest of $227 million was allocated to grants that help individuals recover.
GLO announced the opening of the application for eligible counties and cities on March 15, 2022. Applications closed on August 1, 2022. Each applicant was eligible to submit a total of two applications. All activities had to contribute to the long-term recovery and restoration of infrastructure.
The GLO recognizes that repair and enhancements of local infrastructure are crucial components of long-term recovery and viability of communities.
To learn more, visit https://recovery.texas.gov/2018-floods-2019-disasters/programs/2019-disasters-infrastructure-competition/index.html.
Plum Grove Drainage Improvements – $1,000,000
Tropical Storm Imelda released an unprecedented 3-day total rainfall amount of 28 inches on Plum Grove. That limited the city’s ability to provide an immediate response due to the inundation of flood water. As a result, this project will provide much-needed drainage improvements within Orange Branch Creek which is located in the middle of the city and runs from the northeast down to the southeast. The project will install culverts and restore roads.
Splendora Lift Station Drainage Improvements – $596,625
Imelda flooding submerged the Pinewood Lift Station site, as well as its emergency generator and electrical switchgear located at the northern intersection of Pinewood Drive and First Street. Loss of both primary and emergency back-up power led to a sanitary sewer overflow at Pinewood lift station. Vehicular access, including emergency vehicle access, was not possible because of the depth of flooding in the area. This project includes drainage and generator improvements at the Pinewood Lift Station.
Construction will include the following activities:
Liberty Water, Sewer Improvements – $1,000,000
The project will provide for water and sewer line improvements located within the eastern side of the city along Beaumont Road, Minglewood Road, Glenn Street and Tanner Street. These should reduce overflow concerns for residents and businesses along these streets. The project will make improvements to sewer lines and water lines and remove and replace existing lift stations with gravity sanitary sewer lines.
Descriptions of Other Grants
For a full description of other grants in this batch, see the GLO website.
Posted by Bob Rehak on 3/22/2023 based on information from the Texas General Land Office
2031 Days since Hurricane Harvey and 1280 Days since Imelda
TWDB Needs Feedback on Ranking Method for State Flood Plan
The Texas Water Development Board (TWDB) is soliciting feedback on its proposed scoring matrix to rank efforts for the state’s first flood plan. Each region has submitted proposed projects. The scoring matrix will help rank order them statewide. And the deadline is April Fools’ Day.
TWDB has provided several spreadsheets that show how the criteria and weights would affect ranking of sample projects. But understand that TWDB is only soliciting comments on scoring criteria and their weights at this time, not the rankings of the limited sample. All this is DRAFT data, not final recommendations.
39 Factors in Three Different Categories and Three Groups
TWDB has proposed weighing the relative merits of 39 factors that span three categories with benefits in three more groups:
TWDB uses three types of factors:
“Other” includes such factors as cost and environmental benefits.
The 39 factors include:
Factors (in Risk, Risk Reduction and Other groups) may receive weight in one, two or all three main categories (Evaluations, Projects, Strategies).
Intent: Consistency Across All Regions Statewide
The intent of the TWDB ranking method for the state flood plan is to provide a consistent approach to be used across all Texas regions. The goal: to systematically address the flood hazards with most population, properties and critical facilities at risk in the state during a 1% annual chance flood.
TWDB bases all risk on 1% annual chance/100-year flood estimates.
Areas with widely varying measurements such as population will have answers normalized. Basically, this means adjusting widely varying scales to a common scale (such as 0 to 1) to facilitate comparison.
More Background, Sample Data, Providing Feedback
All relevant ranking workbooks, documents, and the link to the online survey tool are available on the State Flood Planning webpage.
Provide your feedback on this page. It’s a four-question survey about the:
The deadline to submit feedback is Saturday, April 1, 2023.
Importance of Feedback
We have seen how seriously the weights given to such rankings can skew priorities. Consider, for instance, the Equity Prioritization Framework adopted after the fact by a Harris County Judge and two commissioners for proposed 2018 Flood Bond Projects (unrelated to these projects).
So, if you have reservations with the TWDB scoring system, register your complaints NOW. My biggest concerns are that it’s hard to understand. It also contains broken links and typos that get in the way of understanding.
But understanding is critical. Many of the flood-reduction projects needed on the periphery of Harris County will need be addressed by state money. That’s because 10 of our 23 watersheds originate outside the County. I guess that would fall under #39 Regional. But…
That’s kind of strange for a regional plan designed to encourage solutions that cross jurisdictions. Scoring matrix penalizes people on the periphery of large urban areas like Harris County.
I’ve already sent my feedback on that one.
Inconsistencies? TWDB refers to FMS as Flood Management Strategy on its spreadsheet and Flood Management Solution in introductory text.
Another example: In its spreadsheets, footnotes describing the listing of criteria do not correspond in all cases to the criteria listed. Nor does a link work to a supposed explanation of the criteria.
And there’s no description that I could find of how all these categories, measurements and groups fit together.
Finally, it’s not clear how they will treat areas that have a 50% annual chance of flooding (2-year flood). We’ve seen in highly urbanized areas that – after spending hundreds of millions of dollars in some watersheds – the best we can do achieve in some areas is a 25-year level of service. Achieving better would require buying out thousands of homes. What will happen in such cases?
Please make the effort to provide public feedback.
Posted by Bob Rehak on 3/20/2023
2029 Days since Harris County
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.
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.