Note: the post below was condensed and adapted from a longer USGS article. The U.S. Geological Survey (USGS) records continuous stream stage (height of a river) and streamflow (how much water is flowing) with thousands of gages throughout the nation. But how can they determine flood height where no gages exist?
Simple, USGS correlates high water marks after floods with peak gage heights during floods.
“If, for example, records show that stream stage reached 17 feet during a storm, a high-water mark will show the hydrologist what a stage of 17 feet means in terms of how high the water was on the riverbanks and surrounding land.”
Finding high water marks on or near buildings is easy. You look for the mud line or the edge of debris fields. The same principle applies in nature. Sometimes it’s easy.
Think of high water marks like a bathtub ring around a flooded area. Shown here: East End Park after Imelda.
But they’re not always that obvious.
Can You Spot High Water Marks In Pictures Below?
Below are two pictures used by USGS for demonstration purposes. They took the pictures a few days after a record storm. High-water marks show in both pictures, although a hydrologist would only regard one of the marks as being reliable.
Spot the high water marks.
The pictures below are close-ups of the high-water indicators in the top pictures. Did you spot them?
The left picture shows a poison ivy vine with the bottom leaves covered in dried mud. Where the mud stops shows how high the floodwaters reached.
The right-side picture shows a limb that hangs over the same creek. During a flood, rapidly-moving water carries leaves and pine needles, etc.! They stick on limbs that are partially submerged. When the stream recedes the signs remain. The top of the leaves and pine straw indicate how high the creek was during the storm.
The mud on the vine is a much better high-water mark than the tree limb, though. During high water, the fast-moving water will cause partially submerged limbs to move up and down. Therefore, hydrologists would not use the limb to estimate high water.
How High Water Marks Are Used
Planning Development
Documenting high water marks helps plan development near floodplains. If you know that water reaches a certain mark on the bank every few years, you certainly don’t want people building homes and businesses there.
Determining Extent and Severity of Flooding
Gages can determine the height of a flood. But high water marks can also show the width and extent relative to topography.
After most major flood events, USGS partners with FEMA and other state and federal agencies to flag and survey high water marks in areas that flooded. USGS did so here after Harvey to determine the extent and severity of the flooding.
Prediction of Future Floods
Forecasters can use the data associated with high-water marks to predict the severity of future floods, delineate flood zones, and update current maps that may account for changes in upstream conditions.
Flood Frequency Calculations
High-water mark data is also part of the flood-frequency (or recurrence interval) calculations that FEMA uses to identify areas that are likely to experience a 1 percent chance of happening in any given year. These floods, known as 100-year floods, serve as the foundation for flood management planning.
Inundation Mapping
Another significant use: Flood-Inundation Mapping. A flood-inundation map shows the extent and depth of flooding that occurred in various communities as a result of a major storm or flood event. Inundation maps help determine things like:
Changes needed in building codes
Evacuation routes
Heights of bridges and roads.
Once inundation maps are complete, USGS documents them and makes them publicly available online.
Recreating Data from Damaged Gages
If a flood knocks out a gage, as it did with the one at US59 bridge and the Kingwood Country Club on the San Jacinto West Fork, high-water marks can provide maximum height of a flood after the fact. If the cross section of the river is known (or surveyed), hydrologists can even back-calculate the flow rate.
Posted by Bob Rehak on 7/16/2020 with thanks to USGS and Diane Cooper
1052 Days after Hurricane Harvey and 301 since Imelda
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/07/20170915-San-JacintoRJR_3366_308.jpg?fit=1200%2C800&ssl=18001200adminadmin2020-07-16 19:57:082020-07-16 20:23:08How High Water Marks Help Fill Gaps in Flood Knowledge
Almost 40 years ago, when I moved to Houston, I fell in love with the extraordinary beauty of this City. And nowhere in Houston is more beautiful than the Lake Houston Area. The pictures below show why it’s worth fighting for.
Nature in the Lake Houston Area isn’t a place you go to visit. You don’t have to drive or fly to it. It’s all around you. Step out your back door and you’re already there. You’re breathing it. You’re being it.
Harvey Was an Eye Opener
Right up until Hurricane Harvey, I felt, on balance, this was the most perfect place in America to raise my family. Houston offers career opportunities found in few other cities. And the Lake Houston Area, in particular, offers the things my family and I value.
Harvey didn’t change my mind about those things. But it did open my eyes to some things I should have paid closer attention to. All around us, that perfect environment was quietly and steadily being eroded for decades.
It’s not gone. But it is threatened. Every day. More than a thousand other posts on this web site amply chronicle those threats. I won’t dwell on them here. Nor will I dwell on how “the greatest flood ever” kept being replaced by the new “greatest flood ever.”
What We Need to Fight For
I would like, instead, to share several images that show it’s not too late to preserve what we have. But to do that, we have to fight for it.
We need to fight for:
Responsible aggregate mining.
Better development practices that respect nature.
Upstream floodplain regulations that reduce flooding.
Flood mitigation efforts that keep the 100-year floodplain a 100-year floodplain.
Why We Need to Fight
I took all of the pictures below in the last three months. They show what we need to save. All were shot inside America’s fourth largest city, which makes them even more unique.
The Kingwood Country Club’s Lake Course.Can you spot the thousands of homes around it?West Fork of the San Jacinto with Lake Houston on the horizon. Looking SE.For decades, development preserved nature.This is the result.Looking north at Lake Houston across the spillway.Looking south over the Lake Houston Dam toward the industry that powers America and the world.Looking east from the West Fork toward the East Fork of the San Jacinto with Royal Shores between them.Looking north along the East Fork. Kingwood’s East End Park is in the center and Huffman is on the right.Looking SE. FM1960 cuts across Lake Houston and through Huffman in the foreground Looking Southwest in the opposite direction from over FM1960, with Lake Houston in background.Looking East across FM2100 and Huffman toward Kingwood on the other side of the lake.Looking West. The Luce Bayou Interbasin Transfer Project where it enters into Luce Bayou and the headwaters of Lake Houston.Looking north from the Commons on Lake Houston toward where the new Grand Parkway is circling Houston (out of sight) near the top of the frame.This entire area could soon be developed.Looking southeast across Kingwood Park High School. Kingwood, where 70,000 people live, is almost invisible, hidden among the trees between the school and Lake Houston at the top of the frame.Looking north over Forest Cove, toward I-69 and Insperity, Kingwood’s $4 billion company, all hidden in the trees.Looking NW from the confluence of Spring Creek and the San Jacinto West Fork.All of this land has been bought by a developer.Fishing from your back door.
If this isn’t worth fighting for, I don’t know what is.
Bob Rehak
Please join the fight. There’s another legislative session starting in six months.
Posted by Bob Rehak on 7/15/2020
1051 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/07/20200616-RJR_3539.jpg?fit=1200%2C800&ssl=18001200adminadmin2020-07-15 21:33:202020-07-15 23:00:01Worth Fighting For
How do we break the process of building in floodways and then repairing flooded homes with taxpayer-subsidized flood insurance as many as forty times?
A 66-page study by Erica Vilay and Phil Pollman, two candidates for Masters Degrees in Public Policy from Harvard, examines the broken buyout process for flooded homes in Houston floodways. The study also makes recommendations to improve the process. But they won’t revolutionize it. And that may be what this process needs.
The merit in this study is that it takes a holistic view of buyouts and examines them as one of many alternatives available to flood victims living in floodways. From the public’s perspective, buyouts have unquestionable and compelling safety and financial benefits.
Buyouts produce $7 in benefits for every $1 invested. And they take people out of harm’s way.
Speedier Options Available to People In Time of Need
But the process is slow. People have options. And, according to the study, they almost always prefer those other options. In fact, the rate of buyouts is so slow that it will take the City 60 years to meet its 10-year objective, claim the authors.
The paper cited one property that had been repaired a record 40 times. So why is it so difficult to get people to move out of a floodway into housing that won’t jeopardize their lives or lungs?
Vilay and Pollman examine the reasons. The incentives, they say, all favor rebuilding or selling to developers rather than accepting government buyouts.
Tax-subsidized National Flood Insurance Policy premiums remain affordable, offset risk, and usually reimburse homeowners within 60 days after a storm.
Selling to a developer/investor can happen within days or weeks.
Consummating a buyout through the maze of Federal, State, County and Local government agencies can take years.
Federal funding is slow, inflexible, and extremely complex to manage effectively and efficiently.
At the current closing rate, it would take nearly 60 years to buy out the 7,000 habitable structures in Houston floodways, says the study. But Houston-area realtors sell that many homes in a typical MONTH, according to the Greater Houston Partnership! Even in the middle of a pandemic.
“This is a No Brainer”
So one of the big reasons people are reluctant to be bought out is speed. Their lives have just been destroyed in a flood. They need a place to live. Then along comes the government saying, “Let me buy you out. I’ll get you your money in 2-3 years. Or you can just repair your home for the fortieth time and we’ll pay for it immediately.” This is a no-brainer, say the authors.
How hard are buyouts? The authors claim that “As of January 2020, HCFCD has used $3 million out of a $10 million bucket of federal funding allocated to the City for flood events that occurred in 2015.”
Barriers Beyond Slowness
But degree of difficulty and process slowness aren’t the only reasons people shun buyouts.
People get attached to neighbors and neighborhoods.
They may have family living nearby.
There may be a shortage of affordable housing elsewhere.
Alternative housing may be farther from their work.
They may want to stay within a school system.
Goals: Slow Inflow, Speed Outflow
The authors define two goals. They say we need to:
All of these recommendations are solid and, to a large degree, self-explanatory. They are hard to quibble with if you are trying to improve a process.
Incremental Improvements vs. New Concept
The authors never really address, however, whether incremental improvements will achieve the stated goals. Or whether we need to nuke the process and start over with a revolutionary, new concept.
As I read this study, I kept wondering what Steve Jobs, Jeff Bezos, or Elon Musk would recommend. That’s a pretty steep burden to impose on grad students. But we shouldn’t forget that Fred Smith had the idea for Fedex while still a student at Yale.
Each of those people made the world a better place by designing new products or services that leapfrogged incremental improvements in existing systems and made the old way obsolete.
Inside-the-Box Thinking for an Outside-the-Box Problem
Insi-e the-box thinking will certainly produce incremental improvements. But in the estimated time it will take government to buy out 7,000 homes, Houston realtors will sell more than 5 million. That’s 70,000% better. Which would you rather have in your employ?
So I would ask these questions. What if you:
Privatized this process?
Offered flood victims an “instantaneous home SWAP” as they were ripping out sheetrock?
Made flood insurance reflect its true cost?
If ever there was a need for “business process re-engineering,” this is it.
Posted by Bob Rehak on 7/14/2020 with appreciation and admiration for Erica Vilay and Phil Pollman
1050 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2020/07/20200627-RJR_0059-1.jpg?fit=1200%2C800&ssl=18001200adminadmin2020-07-14 18:18:182020-07-14 20:23:45New Harvard Study Examines Barriers to Buyouts; Will Process Improvements Be Enough?
How High Water Marks Help Fill Gaps in Flood Knowledge
Note: the post below was condensed and adapted from a longer USGS article. The U.S. Geological Survey (USGS) records continuous stream stage (height of a river) and streamflow (how much water is flowing) with thousands of gages throughout the nation. But how can they determine flood height where no gages exist?
Simple, USGS correlates high water marks after floods with peak gage heights during floods.
Finding high water marks on or near buildings is easy. You look for the mud line or the edge of debris fields. The same principle applies in nature. Sometimes it’s easy.
But they’re not always that obvious.
Can You Spot High Water Marks In Pictures Below?
Below are two pictures used by USGS for demonstration purposes. They took the pictures a few days after a record storm. High-water marks show in both pictures, although a hydrologist would only regard one of the marks as being reliable.
The pictures below are close-ups of the high-water indicators in the top pictures. Did you spot them?
The left picture shows a poison ivy vine with the bottom leaves covered in dried mud. Where the mud stops shows how high the floodwaters reached.
The right-side picture shows a limb that hangs over the same creek. During a flood, rapidly-moving water carries leaves and pine needles, etc.! They stick on limbs that are partially submerged. When the stream recedes the signs remain. The top of the leaves and pine straw indicate how high the creek was during the storm.
The mud on the vine is a much better high-water mark than the tree limb, though. During high water, the fast-moving water will cause partially submerged limbs to move up and down. Therefore, hydrologists would not use the limb to estimate high water.
How High Water Marks Are Used
Planning Development
Documenting high water marks helps plan development near floodplains. If you know that water reaches a certain mark on the bank every few years, you certainly don’t want people building homes and businesses there.
Determining Extent and Severity of Flooding
Gages can determine the height of a flood. But high water marks can also show the width and extent relative to topography.
After most major flood events, USGS partners with FEMA and other state and federal agencies to flag and survey high water marks in areas that flooded. USGS did so here after Harvey to determine the extent and severity of the flooding.
Prediction of Future Floods
Forecasters can use the data associated with high-water marks to predict the severity of future floods, delineate flood zones, and update current maps that may account for changes in upstream conditions.
Flood Frequency Calculations
High-water mark data is also part of the flood-frequency (or recurrence interval) calculations that FEMA uses to identify areas that are likely to experience a 1 percent chance of happening in any given year. These floods, known as 100-year floods, serve as the foundation for flood management planning.
Inundation Mapping
Another significant use: Flood-Inundation Mapping. A flood-inundation map shows the extent and depth of flooding that occurred in various communities as a result of a major storm or flood event. Inundation maps help determine things like:
Once inundation maps are complete, USGS documents them and makes them publicly available online.
Recreating Data from Damaged Gages
If a flood knocks out a gage, as it did with the one at US59 bridge and the Kingwood Country Club on the San Jacinto West Fork, high-water marks can provide maximum height of a flood after the fact. If the cross section of the river is known (or surveyed), hydrologists can even back-calculate the flow rate.
Posted by Bob Rehak on 7/16/2020 with thanks to USGS and Diane Cooper
1052 Days after Hurricane Harvey and 301 since Imelda
Worth Fighting For
Almost 40 years ago, when I moved to Houston, I fell in love with the extraordinary beauty of this City. And nowhere in Houston is more beautiful than the Lake Houston Area. The pictures below show why it’s worth fighting for.
Nature in the Lake Houston Area isn’t a place you go to visit. You don’t have to drive or fly to it. It’s all around you. Step out your back door and you’re already there. You’re breathing it. You’re being it.
Harvey Was an Eye Opener
Right up until Hurricane Harvey, I felt, on balance, this was the most perfect place in America to raise my family. Houston offers career opportunities found in few other cities. And the Lake Houston Area, in particular, offers the things my family and I value.
Harvey didn’t change my mind about those things. But it did open my eyes to some things I should have paid closer attention to. All around us, that perfect environment was quietly and steadily being eroded for decades.
It’s not gone. But it is threatened. Every day. More than a thousand other posts on this web site amply chronicle those threats. I won’t dwell on them here. Nor will I dwell on how “the greatest flood ever” kept being replaced by the new “greatest flood ever.”
What We Need to Fight For
I would like, instead, to share several images that show it’s not too late to preserve what we have. But to do that, we have to fight for it.
We need to fight for:
Why We Need to Fight
I took all of the pictures below in the last three months. They show what we need to save. All were shot inside America’s fourth largest city, which makes them even more unique.
Please join the fight. There’s another legislative session starting in six months.
Posted by Bob Rehak on 7/15/2020
1051 Days since Hurricane Harvey
New Harvard Study Examines Barriers to Buyouts; Will Process Improvements Be Enough?
How do we break the process of building in floodways and then repairing flooded homes with taxpayer-subsidized flood insurance as many as forty times?
A 66-page study by Erica Vilay and Phil Pollman, two candidates for Masters Degrees in Public Policy from Harvard, examines the broken buyout process for flooded homes in Houston floodways. The study also makes recommendations to improve the process. But they won’t revolutionize it. And that may be what this process needs.
Study Expressly Prepared for City of Houston
Prepared for the City of Houston’s Offices of Recovery and Resilience, the paper is titled “Floodway Buyout Strategy for a Resilient Houston: A Systems Approach for Breaking the Dangerous and Expensive Cycle of Rebuilding in the Floodway.”
The merit in this study is that it takes a holistic view of buyouts and examines them as one of many alternatives available to flood victims living in floodways. From the public’s perspective, buyouts have unquestionable and compelling safety and financial benefits.
Speedier Options Available to People In Time of Need
But the process is slow. People have options. And, according to the study, they almost always prefer those other options. In fact, the rate of buyouts is so slow that it will take the City 60 years to meet its 10-year objective, claim the authors.
Incentives Favor Rebuilding, Not Buyouts
Vilay and Pollman examine the reasons. The incentives, they say, all favor rebuilding or selling to developers rather than accepting government buyouts.
“This is a No Brainer”
So one of the big reasons people are reluctant to be bought out is speed. Their lives have just been destroyed in a flood. They need a place to live. Then along comes the government saying, “Let me buy you out. I’ll get you your money in 2-3 years. Or you can just repair your home for the fortieth time and we’ll pay for it immediately.” This is a no-brainer, say the authors.
How hard are buyouts? The authors claim that “As of January 2020, HCFCD has used $3 million out of a $10 million bucket of federal funding allocated to the City for flood events that occurred in 2015.”
Barriers Beyond Slowness
But degree of difficulty and process slowness aren’t the only reasons people shun buyouts.
Goals: Slow Inflow, Speed Outflow
The authors define two goals. They say we need to:
Process Improvement Recommendations
They then turn their attention to solving these problems and present 13 “sequenced” recommendations. See below.
All of these recommendations are solid and, to a large degree, self-explanatory. They are hard to quibble with if you are trying to improve a process.
Incremental Improvements vs. New Concept
The authors never really address, however, whether incremental improvements will achieve the stated goals. Or whether we need to nuke the process and start over with a revolutionary, new concept.
As I read this study, I kept wondering what Steve Jobs, Jeff Bezos, or Elon Musk would recommend. That’s a pretty steep burden to impose on grad students. But we shouldn’t forget that Fred Smith had the idea for Fedex while still a student at Yale.
Each of those people made the world a better place by designing new products or services that leapfrogged incremental improvements in existing systems and made the old way obsolete.
Inside-the-Box Thinking for an Outside-the-Box Problem
Insi-e the-box thinking will certainly produce incremental improvements. But in the estimated time it will take government to buy out 7,000 homes, Houston realtors will sell more than 5 million. That’s 70,000% better. Which would you rather have in your employ?
So I would ask these questions. What if you:
If ever there was a need for “business process re-engineering,” this is it.
To read the complete Harvard study, click here.
Posted by Bob Rehak on 7/14/2020 with appreciation and admiration for Erica Vilay and Phil Pollman
1050 Days since Hurricane Harvey