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