Jeff Lindner, Harris County’s Meteorologist, has produced an excellent 20-minute video that explains flooding in Southeast Texas and how you can increase your situational awareness during extreme weather events. It’s now on YouTube and is called “Understanding Flooding in Southeast Texas.”
By Jeff Lindner, Harris County Meteorologist
Brief Outline of Video
The video begins with a description of things that make this area unique – namely extreme rainfall on flat topography.
Then Lindner begins by reminding us of extreme rainfalls, such as Tropical Storm Claudette in 1979 which set the U.S. 24-hour rainfall record – 43 inches in one day! To put that in perspective, it took Hurricane Harvey FOUR days to dump 47.4 inches.
Tropical Storm Allison in 2001 dumped 28.5 inches in just 12-hours. It turns out that…
Six of the ten wettest tropical cyclones ever to strike the US mainland struck Southeast Texas!
Jeff Lindner, Harris County Meteorologist
Video is signed for hearing impaired
Then the video:
Defines watersheds, describes local watersheds, and explains how water flows throughout Harris and surrounding counties
Discusses ponding and sheet-flow flooding, unrelated to watersheds
Explains how streets are designed as part of the floodwater retention system
Talks about the Harris County Flood Warning System and the distribution of gages in surrounding counties
Digs into some of the System’s features, such as Near-Real-Time Inundation Mapping
Tells you how sign up for Notification Alerts and explains different types of alerts you can set
Reviews the limitations of home insurance and flood insurance policies.
Who Can Benefit from Watching?
Many types of people can benefit from watching this video:
People new to the area
Young people
Anyone buying property or new homes
Long-term residents who have had close calls during previous floods
Those without flood insurance or those considering buying it.
Regarding insurance, Lindner reminds us that it takes 30-days for flood insurance to go into effect and that you can’t buy flood insurance when there’s a named storm in the Gulf. So the time to buy it is well before hurricane season, which starts on June 1.
It’s also important to remember that flooding can happen in non-tropical storms that occur in virtually any month of the year. Tax Day and Memorial Day storms are good examples. The Tax Day storm dumped 23.5 inches of rain in 12-hours!
Of the 154,170 estimated homes that flooded across Harris County during Harvey, only 36% had active flood insurance policies in place the day before the storm struck…64% did not have flood insurance.
If you think that government disaster relief will make you whole soon after a flood, think again. Five and a half years after Harvey, people are still waiting for aid or in the process of rebuilding their homes.
Posted by Bob Rehak on 3/26/2023
2035 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/03/Screenshot-2023-03-26-at-2.02.12-PM.png?fit=1614%2C798&ssl=17981614adminadmin2023-03-26 14:23:452023-03-26 14:23:47Intro to Flooding in Southeast Texas
Since 1980, tropical cyclones have been the costliest type of weather-related disaster in the United States, according to NOAA’s National Centers for Environmental Information (NCEI). The NCEI study includes events that caused at least one billion dollars in damages when adjusted for inflation.
Accounting for just under a fifth (17.6%) of the total number of events, tropical cyclones have caused more than half (53.8%) of the total damages.
Tropical cyclones also cause more deaths than any other type of weather-related disaster.
Types of Events Compared
NCEI monitors the following types of disasters:
Hurricanes
Drought
Inland floods
Severe local storms
Wildfires
Crop freeze events
Winter storms
Damages Quantified
Since 1980, the U.S. has sustained at least 341 billion-dollar, weather disasters (including Consumer Price Index adjustment to 2022). The total cost of these 341 events exceeds $2.4 trillion.
Out of that total, tropical cyclones have caused a combined $1.3 trillion in total damages—with an average of $22.2 billion per event. They leave droughts in the dust. Droughts are the second costliest.
Rank ordered based on average cost per event, they line up like this:
Tropical Cyclones – $22.2 billion
Drought – $10.9 billion
Wildfires – $6.3 billion
Flooding – $4.8 billion
Winter storms – $4.3 billion
Freezes – $3.9 billion
Severe storms – $2.4 billion
The table below contains additional information about the frequency of billion dollar events, their total costs, and the number of deaths they cause.
All parts of the county experience weather-related disasters. The dominant types of disasters vary by region. For instance winter storms are more costly in the north, droughts in the plains, and tropical cyclones along seaboards.
Cost of Disasters Increasing
Both the number and cost of billion-dollar weather-related disasters are increasing over time. Here’s the breakdown by year.
Exercise caution when interpreting the upward slope of the graph above. It would be easy to attribute the slope solely to climate change and many people will,
But NCEI points out that increases in population, and material wealth over the last several decades are an important factor for higher damages. So are the locations of population concentrations and failure to adopt better building codes.
“These trends are further complicated by the fact that many population centers and infrastructure exist in vulnerable areas like coasts and river floodplains, while building codes are often insufficient in reducing damage from extreme events,” says NCEI.
Data Sources
In calculating the cost assessments, we receive input from a variety of public and private data sources including:
Insurance Services Office
Federal Emergency Management Agency
U.S. Department of Agriculture
National Interagency Fire Center
Energy Information Administration
U.S. Army Corps
State agencies
Other partners
Costs Include…
Each of these data sources provides key pieces of information that capture the total, direct costs—both insured and uninsured—of weather and climate events. These costs include:
Physical damage to residential, commercial, and government or municipal buildings
Material assets within a building
Time element losses like business interruption
Vehicles and boats
Offshore energy platforms, electrical infrastructure, military bases
Public infrastructure like roads, bridges, levees, buildings
Agricultural assets like crops, livestock, and timber
Disaster restoration and wildfire suppression costs
One of the key transformations is scaling up insured loss data to account for uninsured and underinsured losses, which differs by peril, geography, and asset class.
Costs Do Not Include…
However, these loss assessments do not take into account losses to natural capital or assets, health-care-related losses, or values associated with loss of life. Therefore, consider NCEI estimates conservative with respect to what is truly lost, but cannot be completely measured.
Posted by Bob Rehak based on Information from NCEI
2034 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2023/03/Screenshot-2023-03-25-at-8.50.23-PM.png?fit=2258%2C1204&ssl=112042258adminadmin2023-03-25 21:49:042023-03-26 09:51:05Tropical Cyclones Costliest Type of Weather-Related Disaster By Far
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.
Intro to Flooding in Southeast Texas
Jeff Lindner, Harris County’s Meteorologist, has produced an excellent 20-minute video that explains flooding in Southeast Texas and how you can increase your situational awareness during extreme weather events. It’s now on YouTube and is called “Understanding Flooding in Southeast Texas.”
Brief Outline of Video
The video begins with a description of things that make this area unique – namely extreme rainfall on flat topography.
Then Lindner begins by reminding us of extreme rainfalls, such as Tropical Storm Claudette in 1979 which set the U.S. 24-hour rainfall record – 43 inches in one day! To put that in perspective, it took Hurricane Harvey FOUR days to dump 47.4 inches.
Tropical Storm Allison in 2001 dumped 28.5 inches in just 12-hours. It turns out that…
Then the video:
Who Can Benefit from Watching?
Many types of people can benefit from watching this video:
Regarding insurance, Lindner reminds us that it takes 30-days for flood insurance to go into effect and that you can’t buy flood insurance when there’s a named storm in the Gulf. So the time to buy it is well before hurricane season, which starts on June 1.
It’s also important to remember that flooding can happen in non-tropical storms that occur in virtually any month of the year. Tax Day and Memorial Day storms are good examples. The Tax Day storm dumped 23.5 inches of rain in 12-hours!
Of the 154,170 estimated homes that flooded across Harris County during Harvey, only 36% had active flood insurance policies in place the day before the storm struck…64% did not have flood insurance.
If you think that government disaster relief will make you whole soon after a flood, think again. Five and a half years after Harvey, people are still waiting for aid or in the process of rebuilding their homes.
Posted by Bob Rehak on 3/26/2023
2035 Days since Hurricane Harvey
Tropical Cyclones Costliest Type of Weather-Related Disaster By Far
Since 1980, tropical cyclones have been the costliest type of weather-related disaster in the United States, according to NOAA’s National Centers for Environmental Information (NCEI). The NCEI study includes events that caused at least one billion dollars in damages when adjusted for inflation.
Accounting for just under a fifth (17.6%) of the total number of events, tropical cyclones have caused more than half (53.8%) of the total damages.
Tropical cyclones also cause more deaths than any other type of weather-related disaster.
Types of Events Compared
NCEI monitors the following types of disasters:
Damages Quantified
Since 1980, the U.S. has sustained at least 341 billion-dollar, weather disasters (including Consumer Price Index adjustment to 2022). The total cost of these 341 events exceeds $2.4 trillion.
Out of that total, tropical cyclones have caused a combined $1.3 trillion in total damages—with an average of $22.2 billion per event. They leave droughts in the dust. Droughts are the second costliest.
Rank ordered based on average cost per event, they line up like this:
The table below contains additional information about the frequency of billion dollar events, their total costs, and the number of deaths they cause.
No Region Immune
All parts of the county experience weather-related disasters. The dominant types of disasters vary by region. For instance winter storms are more costly in the north, droughts in the plains, and tropical cyclones along seaboards.
Cost of Disasters Increasing
Both the number and cost of billion-dollar weather-related disasters are increasing over time. Here’s the breakdown by year.
Reasons Cited for Increases
Exercise caution when interpreting the upward slope of the graph above. It would be easy to attribute the slope solely to climate change and many people will,
But NCEI points out that increases in population, and material wealth over the last several decades are an important factor for higher damages. So are the locations of population concentrations and failure to adopt better building codes.
“These trends are further complicated by the fact that many population centers and infrastructure exist in vulnerable areas like coasts and river floodplains, while building codes are often insufficient in reducing damage from extreme events,” says NCEI.
Data Sources
In calculating the cost assessments, we receive input from a variety of public and private data sources including:
Costs Include…
Each of these data sources provides key pieces of information that capture the total, direct costs—both insured and uninsured—of weather and climate events. These costs include:
One of the key transformations is scaling up insured loss data to account for uninsured and underinsured losses, which differs by peril, geography, and asset class.
Costs Do Not Include…
However, these loss assessments do not take into account losses to natural capital or assets, health-care-related losses, or values associated with loss of life. Therefore, consider NCEI estimates conservative with respect to what is truly lost, but cannot be completely measured.
Posted by Bob Rehak based on Information from NCEI
2034 Days since Hurricane Harvey
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