October 27, 2025 • 9 mins
Levee systems make it possible for us to live alongside bodies of water with less danger of flooding. Learn how engineers design them -- and why levees sometimes fail -- in this episode of BrainStuff, based on this article: https://science.howstuffworks.com/engineering/structural/levee.htm
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Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:01):
Welcome to Brainstuff, a production of iHeartRadio, Hey Brainstuff Lorn
Bogelbaum here in his poem The Dry Salvages, T. S.
Eliot described the river as a strong, brown god, a
powerful force that, while often patient and nurturing, proves itself
untamable and merciless. The greatest cities in human history have
(00:26):
risen up on the banks of rivers and by the seaside,
but in doing so, their builders chose to live in
close confines with an unruly force. Rivers have surged, washing
away whole communities or changed course, abandoning prosperous kingdoms to
the dust. Even today, ocean storms threatened to decimate centuries
(00:47):
worth of human endeavor. Humans have attempted to conquer the
problems of changing water levels for thousands of years. One
of the oldest weapons we've wielded against the rivers and
oceans is the levee, also known as a dike. A
levee is simply a man made embankment built to physically
block a river from overflowing its banks, or to prevent
(01:09):
ocean waves from washing into undesired areas. In New Orleans,
for example, the levees attempt to perform dual duties. On
one side of the city, levees protect against floods from
the Mississippi River, and on the other side they help
to keep lake punch train in place. In parts of
the Netherlands, dikes stop ocean waters from reclaiming thousands of
(01:31):
miles of land, much of which is either at or
below sea level. The famous windmills of Holland pump water
from behind the dikes and back out to sea to
keep the land dry. As in Louisiana and for another example,
the Florida Everglades region, there are parts of the Netherlands
where engineers have created new dry land with complex water
(01:52):
management systems. A levee is typically little more than a
mound of not very permeable soil like clay, wider at
the base and narrower at the top, but they can
be a little or a lot more complex, comprised of
different layers of soils, especially designed fabrics to reinforce the soil,
concrete floodwalls, pump stations to control water levels, and all
(02:15):
kinds of sensors to help watch four potential problems. They
can feature paved paths and gates for pedestrian and vehicle
traffic bridges, and even parks with landscaping and esthetic architectural features,
you might not even realize that what you're standing on
is part of a levee system. Levees often run in
(02:36):
a long strip, sometimes for many miles, along a river, lake,
or ocean. Just for example, levees along the Mississippi River
may range from ten to twenty feet tall that's about
three to seven meters. In Holland, they can top thirty
feet that's ten meters, but there's no set height for levees.
Their measurements vary according to storms that the area receives,
(02:59):
even if those storms occur only once every hundred or
one thousand years. Every levee system is different based on
the particular conditions and risks in an area. They can
incorporate salt water or freshwater marshes to help absorb flooding.
Coastal systems especially may be helped by periodic beach renourishment
to replace sand, soil, and rocks that are eroded during storms,
(03:23):
and levee systems can be built in conjunction with dams
to better manage a whole area's watershed. A living by
the water provides humans with a number of advantages a
fertile farmland, transportation, trade, and hydroelectric power. Levees allow humans
to enjoy these assets with less fear of flooding. While
strolling along the beach or enjoying a picnic by a riverbank.
(03:45):
It's easy to forget the strength of water until floods
and storms jar us to remember. In nineteen thirteen, the
Ohio River and its tributaries flooded, submerging several cities and
killing one thousand. In nineteen twenty seven, the Mississippi River
swelled during several months of heavy rain, charging through a
line of levees and flooding an area the size of Ireland,
(04:07):
displacing hundreds of thousands of Southerners. In nineteen fifty three,
the North Sea broke through netherlands ancient system of dikes
and killed thousands. Through these and other disasters, our scientific
understanding of waterways evolved. Engineers now operate with the base
concept that water cannot be fully controlled, but can be
(04:30):
mitigated through broad and interconnected flood risk management systems. But
even with this understanding, disasters still happen. Back in two
thousand and five, Hurricane Katrina breached New Orleans levees. Much
of the city lies below sea level. Throughout history, low
lying boggy areas have been pumped dry to create new land.
(04:54):
Much of this reclaimed land has sunk as it dried out.
The entire city now depends on the levees, along with
massive pumping stations to keep the water out. Katrina flooded
eighty percent of the city, killing some one thousand, six
hundred people and displacing about two hundred thousand others. But
how could this happen in a modern city. Investigations over
(05:17):
the following decade pointed to a few major reasons. First,
there was insufficient planning. New Orleans levee designs were based
on an outdated study from nineteen sixty five. Engineers built
the system with the goal of standing up to the
worst storm possible in two hundred years. Unfortunately, the study
greatly miscalculated how powerful potential storms could be. Second, the
(05:42):
design was risky. New Orleans levees were built to sustain
the city's growth, unlike the levees and neighboring areas, which
were built to provide safety. As result, New Orleans levees
were shorter and weaker. Third, the safety of the system
was compromised by bureaucracy. No central agency was in charge
of maintaining the levees. This task instead fell to several
(06:06):
different private firms and government agencies, leading to communication problems
and the breakdown of various upgrade projects. Fourth, there was
poor maintenance. Levees require constant upkeep. As the land in
New Orleans sinks, so do the levees. And Fifth, there
were insufficient funds. The US Army Corps Engineers, which oversees
(06:29):
the design and construction of levees, had been hit by
budget cuts. This left the agency with fewer experienced engineers.
As New Orleans rebuilt from the disaster, some of these
concerns were addressed. The Army Corps Engineers designed a system
of floodwalls and levees snaking three hundred and fifty miles
that's five hundred and fifty kilometers through five parishes, at
(06:52):
a cost of over fourteen billion dollars. However, that was
now twenty years ago and maintenance is an ongoing issue.
They estimate that it'll cost another billion dollars in upkeep
over the next fifty years, and that kind of funding
is frustratingly hard to come by. The Netherlands faced a
similar situation following the flood in nineteen fifty three. In
(07:15):
the decades that followed, engineers set out to build a
new kind of barrier against the sea. They steadily replaced
the old dike system which had been in place since
the medieval ages, and created, weirdly enough, right around three
hundred and fifty miles of what many consider the safest
levee system in the world. They started by reevaluating their
entire system in several key ways. They set out thinking
(07:39):
long term, like really long term, new orleands. Old levees
were built to with stand the strongest possible storm in
two hundred years. Netherlands engineers designed a system strong enough
to match the kind of catastrophic storm that only occurs
once in ten thousand years. Also, instead of constructing increasingly
bigger solid barriers like levees and flood walls, they sought
(08:02):
to create better ways of absorbing floodwaters in marsh plains
and specially constructed rivers. In some cases, this involved setting
dikes farther back from the water. The engineers also developed
tough synthetic textiles to better anchor earth than levees These
prevent soil movement and water penetration. The New Lands Levee
(08:23):
system began using this technology following Hurricane Katrina. The Netherlands
also implemented more stringent and centralized control and maintenance of
their dikes and now use automated surveillance systems to keep
an eye on how their levees are holding up. They
installed fiber, optic and electronic sensors in dike structures to
report changes back to a central monitoring system. The several
(08:47):
other systems monitor water pressure and water level. A major
challenge in maintaining levee systems in urban areas is urban sprawl,
which can place increased pressure on existing levee structures. Levees
require regular maintenance, constant monitoring, and a long term appreciation
for how rivers, oceans, and storms behave. When these are
(09:10):
in place, communities can thrive safely along the beauty and
convenience of coastal and riverside areas. It's when we fail
to remember this that rivers and oceans become destroyers. Today's
episode is based on the article what is a levee?
On HowStuffWorks dot com, written by Marshall Brain and Robert
(09:32):
Lamb brain Stuff is production of iHeartRadio in partnership with
how stuffworks dot Com and is produced by Tyler Klang.
Four more podcasts from my heart Radio. Visit the iHeartRadio app,
Apple Podcasts, or wherever you listen to your favorite shows.
Welcome to Brainstuff, a production of iHeartRadio, Hey Brainstuff Lorn
Bogelbaum here in his poem The Dry Salvages, T. S.
Eliot described the river as a strong, brown god, a
powerful force that, while often patient and nurturing, proves itself
untamable and merciless. The greatest cities in human history have
(00:26):
risen up on the banks of rivers and by the seaside,
but in doing so, their builders chose to live in
close confines with an unruly force. Rivers have surged, washing
away whole communities or changed course, abandoning prosperous kingdoms to
the dust. Even today, ocean storms threatened to decimate centuries
(00:47):
worth of human endeavor. Humans have attempted to conquer the
problems of changing water levels for thousands of years. One
of the oldest weapons we've wielded against the rivers and
oceans is the levee, also known as a dike. A
levee is simply a man made embankment built to physically
block a river from overflowing its banks, or to prevent
(01:09):
ocean waves from washing into undesired areas. In New Orleans,
for example, the levees attempt to perform dual duties. On
one side of the city, levees protect against floods from
the Mississippi River, and on the other side they help
to keep lake punch train in place. In parts of
the Netherlands, dikes stop ocean waters from reclaiming thousands of
(01:31):
miles of land, much of which is either at or
below sea level. The famous windmills of Holland pump water
from behind the dikes and back out to sea to
keep the land dry. As in Louisiana and for another example,
the Florida Everglades region, there are parts of the Netherlands
where engineers have created new dry land with complex water
(01:52):
management systems. A levee is typically little more than a
mound of not very permeable soil like clay, wider at
the base and narrower at the top, but they can
be a little or a lot more complex, comprised of
different layers of soils, especially designed fabrics to reinforce the soil,
concrete floodwalls, pump stations to control water levels, and all
(02:15):
kinds of sensors to help watch four potential problems. They
can feature paved paths and gates for pedestrian and vehicle
traffic bridges, and even parks with landscaping and esthetic architectural features,
you might not even realize that what you're standing on
is part of a levee system. Levees often run in
(02:36):
a long strip, sometimes for many miles, along a river, lake,
or ocean. Just for example, levees along the Mississippi River
may range from ten to twenty feet tall that's about
three to seven meters. In Holland, they can top thirty
feet that's ten meters, but there's no set height for levees.
Their measurements vary according to storms that the area receives,
(02:59):
even if those storms occur only once every hundred or
one thousand years. Every levee system is different based on
the particular conditions and risks in an area. They can
incorporate salt water or freshwater marshes to help absorb flooding.
Coastal systems especially may be helped by periodic beach renourishment
to replace sand, soil, and rocks that are eroded during storms,
(03:23):
and levee systems can be built in conjunction with dams
to better manage a whole area's watershed. A living by
the water provides humans with a number of advantages a
fertile farmland, transportation, trade, and hydroelectric power. Levees allow humans
to enjoy these assets with less fear of flooding. While
strolling along the beach or enjoying a picnic by a riverbank.
(03:45):
It's easy to forget the strength of water until floods
and storms jar us to remember. In nineteen thirteen, the
Ohio River and its tributaries flooded, submerging several cities and
killing one thousand. In nineteen twenty seven, the Mississippi River
swelled during several months of heavy rain, charging through a
line of levees and flooding an area the size of Ireland,
(04:07):
displacing hundreds of thousands of Southerners. In nineteen fifty three,
the North Sea broke through netherlands ancient system of dikes
and killed thousands. Through these and other disasters, our scientific
understanding of waterways evolved. Engineers now operate with the base
concept that water cannot be fully controlled, but can be
(04:30):
mitigated through broad and interconnected flood risk management systems. But
even with this understanding, disasters still happen. Back in two
thousand and five, Hurricane Katrina breached New Orleans levees. Much
of the city lies below sea level. Throughout history, low
lying boggy areas have been pumped dry to create new land.
(04:54):
Much of this reclaimed land has sunk as it dried out.
The entire city now depends on the levees, along with
massive pumping stations to keep the water out. Katrina flooded
eighty percent of the city, killing some one thousand, six
hundred people and displacing about two hundred thousand others. But
how could this happen in a modern city. Investigations over
(05:17):
the following decade pointed to a few major reasons. First,
there was insufficient planning. New Orleans levee designs were based
on an outdated study from nineteen sixty five. Engineers built
the system with the goal of standing up to the
worst storm possible in two hundred years. Unfortunately, the study
greatly miscalculated how powerful potential storms could be. Second, the
(05:42):
design was risky. New Orleans levees were built to sustain
the city's growth, unlike the levees and neighboring areas, which
were built to provide safety. As result, New Orleans levees
were shorter and weaker. Third, the safety of the system
was compromised by bureaucracy. No central agency was in charge
of maintaining the levees. This task instead fell to several
(06:06):
different private firms and government agencies, leading to communication problems
and the breakdown of various upgrade projects. Fourth, there was
poor maintenance. Levees require constant upkeep. As the land in
New Orleans sinks, so do the levees. And Fifth, there
were insufficient funds. The US Army Corps Engineers, which oversees
(06:29):
the design and construction of levees, had been hit by
budget cuts. This left the agency with fewer experienced engineers.
As New Orleans rebuilt from the disaster, some of these
concerns were addressed. The Army Corps Engineers designed a system
of floodwalls and levees snaking three hundred and fifty miles
that's five hundred and fifty kilometers through five parishes, at
(06:52):
a cost of over fourteen billion dollars. However, that was
now twenty years ago and maintenance is an ongoing issue.
They estimate that it'll cost another billion dollars in upkeep
over the next fifty years, and that kind of funding
is frustratingly hard to come by. The Netherlands faced a
similar situation following the flood in nineteen fifty three. In
(07:15):
the decades that followed, engineers set out to build a
new kind of barrier against the sea. They steadily replaced
the old dike system which had been in place since
the medieval ages, and created, weirdly enough, right around three
hundred and fifty miles of what many consider the safest
levee system in the world. They started by reevaluating their
entire system in several key ways. They set out thinking
(07:39):
long term, like really long term, new orleands. Old levees
were built to with stand the strongest possible storm in
two hundred years. Netherlands engineers designed a system strong enough
to match the kind of catastrophic storm that only occurs
once in ten thousand years. Also, instead of constructing increasingly
bigger solid barriers like levees and flood walls, they sought
(08:02):
to create better ways of absorbing floodwaters in marsh plains
and specially constructed rivers. In some cases, this involved setting
dikes farther back from the water. The engineers also developed
tough synthetic textiles to better anchor earth than levees These
prevent soil movement and water penetration. The New Lands Levee
(08:23):
system began using this technology following Hurricane Katrina. The Netherlands
also implemented more stringent and centralized control and maintenance of
their dikes and now use automated surveillance systems to keep
an eye on how their levees are holding up. They
installed fiber, optic and electronic sensors in dike structures to
report changes back to a central monitoring system. The several
(08:47):
other systems monitor water pressure and water level. A major
challenge in maintaining levee systems in urban areas is urban sprawl,
which can place increased pressure on existing levee structures. Levees
require regular maintenance, constant monitoring, and a long term appreciation
for how rivers, oceans, and storms behave. When these are
(09:10):
in place, communities can thrive safely along the beauty and
convenience of coastal and riverside areas. It's when we fail
to remember this that rivers and oceans become destroyers. Today's
episode is based on the article what is a levee?
On HowStuffWorks dot com, written by Marshall Brain and Robert
(09:32):
Lamb brain Stuff is production of iHeartRadio in partnership with
how stuffworks dot Com and is produced by Tyler Klang.
Four more podcasts from my heart Radio. Visit the iHeartRadio app,
Apple Podcasts, or wherever you listen to your favorite shows.
BrainStuff News
Host
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