1 00:00:01,840 --> 00:00:07,960 Speaker 1: Welcome to Brainstuff, a production of iHeartRadio, Hey Brainstuff Lorn 2 00:00:08,000 --> 00:00:13,000 Speaker 1: Bogelbaum here in his poem The Dry Salvages, T. S. 3 00:00:13,039 --> 00:00:17,000 Speaker 1: Eliot described the river as a strong, brown god, a 4 00:00:17,239 --> 00:00:21,279 Speaker 1: powerful force that, while often patient and nurturing, proves itself 5 00:00:21,400 --> 00:00:26,200 Speaker 1: untamable and merciless. The greatest cities in human history have 6 00:00:26,320 --> 00:00:29,160 Speaker 1: risen up on the banks of rivers and by the seaside, 7 00:00:29,320 --> 00:00:32,519 Speaker 1: but in doing so, their builders chose to live in 8 00:00:32,600 --> 00:00:38,000 Speaker 1: close confines with an unruly force. Rivers have surged, washing 9 00:00:38,080 --> 00:00:42,800 Speaker 1: away whole communities or changed course, abandoning prosperous kingdoms to 10 00:00:42,800 --> 00:00:47,560 Speaker 1: the dust. Even today, ocean storms threatened to decimate centuries 11 00:00:47,600 --> 00:00:51,519 Speaker 1: worth of human endeavor. Humans have attempted to conquer the 12 00:00:51,560 --> 00:00:56,200 Speaker 1: problems of changing water levels for thousands of years. One 13 00:00:56,240 --> 00:00:59,040 Speaker 1: of the oldest weapons we've wielded against the rivers and 14 00:00:59,080 --> 00:01:02,640 Speaker 1: oceans is the levee, also known as a dike. A 15 00:01:02,720 --> 00:01:06,240 Speaker 1: levee is simply a man made embankment built to physically 16 00:01:06,280 --> 00:01:09,279 Speaker 1: block a river from overflowing its banks, or to prevent 17 00:01:09,319 --> 00:01:14,520 Speaker 1: ocean waves from washing into undesired areas. In New Orleans, 18 00:01:14,520 --> 00:01:18,400 Speaker 1: for example, the levees attempt to perform dual duties. On 19 00:01:18,400 --> 00:01:20,920 Speaker 1: one side of the city, levees protect against floods from 20 00:01:20,959 --> 00:01:23,920 Speaker 1: the Mississippi River, and on the other side they help 21 00:01:23,959 --> 00:01:27,640 Speaker 1: to keep lake punch train in place. In parts of 22 00:01:27,680 --> 00:01:31,319 Speaker 1: the Netherlands, dikes stop ocean waters from reclaiming thousands of 23 00:01:31,319 --> 00:01:33,840 Speaker 1: miles of land, much of which is either at or 24 00:01:33,920 --> 00:01:37,920 Speaker 1: below sea level. The famous windmills of Holland pump water 25 00:01:38,040 --> 00:01:40,200 Speaker 1: from behind the dikes and back out to sea to 26 00:01:40,360 --> 00:01:44,920 Speaker 1: keep the land dry. As in Louisiana and for another example, 27 00:01:45,000 --> 00:01:48,160 Speaker 1: the Florida Everglades region, there are parts of the Netherlands 28 00:01:48,200 --> 00:01:52,200 Speaker 1: where engineers have created new dry land with complex water 29 00:01:52,280 --> 00:01:56,440 Speaker 1: management systems. A levee is typically little more than a 30 00:01:56,480 --> 00:02:00,800 Speaker 1: mound of not very permeable soil like clay, wider at 31 00:02:00,840 --> 00:02:04,000 Speaker 1: the base and narrower at the top, but they can 32 00:02:04,080 --> 00:02:07,400 Speaker 1: be a little or a lot more complex, comprised of 33 00:02:07,400 --> 00:02:11,480 Speaker 1: different layers of soils, especially designed fabrics to reinforce the soil, 34 00:02:11,880 --> 00:02:15,760 Speaker 1: concrete floodwalls, pump stations to control water levels, and all 35 00:02:15,840 --> 00:02:19,680 Speaker 1: kinds of sensors to help watch four potential problems. They 36 00:02:19,760 --> 00:02:23,440 Speaker 1: can feature paved paths and gates for pedestrian and vehicle 37 00:02:23,480 --> 00:02:29,880 Speaker 1: traffic bridges, and even parks with landscaping and esthetic architectural features, 38 00:02:30,080 --> 00:02:32,280 Speaker 1: you might not even realize that what you're standing on 39 00:02:32,560 --> 00:02:36,680 Speaker 1: is part of a levee system. Levees often run in 40 00:02:36,720 --> 00:02:40,440 Speaker 1: a long strip, sometimes for many miles, along a river, lake, 41 00:02:40,560 --> 00:02:44,720 Speaker 1: or ocean. Just for example, levees along the Mississippi River 42 00:02:44,840 --> 00:02:47,560 Speaker 1: may range from ten to twenty feet tall that's about 43 00:02:47,560 --> 00:02:51,440 Speaker 1: three to seven meters. In Holland, they can top thirty 44 00:02:51,440 --> 00:02:55,680 Speaker 1: feet that's ten meters, but there's no set height for levees. 45 00:02:55,919 --> 00:02:59,040 Speaker 1: Their measurements vary according to storms that the area receives, 46 00:02:59,320 --> 00:03:02,000 Speaker 1: even if those storms occur only once every hundred or 47 00:03:02,000 --> 00:03:06,840 Speaker 1: one thousand years. Every levee system is different based on 48 00:03:06,919 --> 00:03:10,520 Speaker 1: the particular conditions and risks in an area. They can 49 00:03:10,560 --> 00:03:14,360 Speaker 1: incorporate salt water or freshwater marshes to help absorb flooding. 50 00:03:15,080 --> 00:03:18,880 Speaker 1: Coastal systems especially may be helped by periodic beach renourishment 51 00:03:19,000 --> 00:03:22,440 Speaker 1: to replace sand, soil, and rocks that are eroded during storms, 52 00:03:23,639 --> 00:03:26,520 Speaker 1: and levee systems can be built in conjunction with dams 53 00:03:26,560 --> 00:03:30,280 Speaker 1: to better manage a whole area's watershed. A living by 54 00:03:30,320 --> 00:03:33,240 Speaker 1: the water provides humans with a number of advantages a 55 00:03:33,280 --> 00:03:39,160 Speaker 1: fertile farmland, transportation, trade, and hydroelectric power. Levees allow humans 56 00:03:39,160 --> 00:03:42,840 Speaker 1: to enjoy these assets with less fear of flooding. While 57 00:03:42,960 --> 00:03:45,720 Speaker 1: strolling along the beach or enjoying a picnic by a riverbank. 58 00:03:45,880 --> 00:03:49,600 Speaker 1: It's easy to forget the strength of water until floods 59 00:03:49,600 --> 00:03:53,760 Speaker 1: and storms jar us to remember. In nineteen thirteen, the 60 00:03:53,800 --> 00:03:57,800 Speaker 1: Ohio River and its tributaries flooded, submerging several cities and 61 00:03:57,880 --> 00:04:01,480 Speaker 1: killing one thousand. In nineteen twenty seven, the Mississippi River 62 00:04:01,560 --> 00:04:04,760 Speaker 1: swelled during several months of heavy rain, charging through a 63 00:04:04,800 --> 00:04:07,440 Speaker 1: line of levees and flooding an area the size of Ireland, 64 00:04:07,720 --> 00:04:12,200 Speaker 1: displacing hundreds of thousands of Southerners. In nineteen fifty three, 65 00:04:12,560 --> 00:04:15,680 Speaker 1: the North Sea broke through netherlands ancient system of dikes 66 00:04:15,720 --> 00:04:21,880 Speaker 1: and killed thousands. Through these and other disasters, our scientific 67 00:04:22,000 --> 00:04:26,320 Speaker 1: understanding of waterways evolved. Engineers now operate with the base 68 00:04:26,400 --> 00:04:30,240 Speaker 1: concept that water cannot be fully controlled, but can be 69 00:04:30,400 --> 00:04:36,080 Speaker 1: mitigated through broad and interconnected flood risk management systems. But 70 00:04:36,320 --> 00:04:41,800 Speaker 1: even with this understanding, disasters still happen. Back in two 71 00:04:41,839 --> 00:04:45,839 Speaker 1: thousand and five, Hurricane Katrina breached New Orleans levees. Much 72 00:04:45,839 --> 00:04:49,440 Speaker 1: of the city lies below sea level. Throughout history, low 73 00:04:49,520 --> 00:04:52,920 Speaker 1: lying boggy areas have been pumped dry to create new land. 74 00:04:54,000 --> 00:04:56,719 Speaker 1: Much of this reclaimed land has sunk as it dried out. 75 00:04:57,600 --> 00:05:00,479 Speaker 1: The entire city now depends on the levees, along with 76 00:05:00,560 --> 00:05:05,120 Speaker 1: massive pumping stations to keep the water out. Katrina flooded 77 00:05:05,240 --> 00:05:08,279 Speaker 1: eighty percent of the city, killing some one thousand, six 78 00:05:08,360 --> 00:05:13,240 Speaker 1: hundred people and displacing about two hundred thousand others. But 79 00:05:13,400 --> 00:05:17,240 Speaker 1: how could this happen in a modern city. Investigations over 80 00:05:17,279 --> 00:05:21,960 Speaker 1: the following decade pointed to a few major reasons. First, 81 00:05:22,120 --> 00:05:26,400 Speaker 1: there was insufficient planning. New Orleans levee designs were based 82 00:05:26,440 --> 00:05:30,520 Speaker 1: on an outdated study from nineteen sixty five. Engineers built 83 00:05:30,520 --> 00:05:32,440 Speaker 1: the system with the goal of standing up to the 84 00:05:32,440 --> 00:05:37,159 Speaker 1: worst storm possible in two hundred years. Unfortunately, the study 85 00:05:37,200 --> 00:05:42,440 Speaker 1: greatly miscalculated how powerful potential storms could be. Second, the 86 00:05:42,480 --> 00:05:46,400 Speaker 1: design was risky. New Orleans levees were built to sustain 87 00:05:46,440 --> 00:05:49,560 Speaker 1: the city's growth, unlike the levees and neighboring areas, which 88 00:05:49,600 --> 00:05:53,480 Speaker 1: were built to provide safety. As result, New Orleans levees 89 00:05:53,520 --> 00:05:58,120 Speaker 1: were shorter and weaker. Third, the safety of the system 90 00:05:58,160 --> 00:06:02,440 Speaker 1: was compromised by bureaucracy. No central agency was in charge 91 00:06:02,480 --> 00:06:06,400 Speaker 1: of maintaining the levees. This task instead fell to several 92 00:06:06,440 --> 00:06:10,839 Speaker 1: different private firms and government agencies, leading to communication problems 93 00:06:10,880 --> 00:06:15,279 Speaker 1: and the breakdown of various upgrade projects. Fourth, there was 94 00:06:15,320 --> 00:06:20,160 Speaker 1: poor maintenance. Levees require constant upkeep. As the land in 95 00:06:20,200 --> 00:06:24,800 Speaker 1: New Orleans sinks, so do the levees. And Fifth, there 96 00:06:24,800 --> 00:06:29,640 Speaker 1: were insufficient funds. The US Army Corps Engineers, which oversees 97 00:06:29,680 --> 00:06:32,280 Speaker 1: the design and construction of levees, had been hit by 98 00:06:32,279 --> 00:06:36,560 Speaker 1: budget cuts. This left the agency with fewer experienced engineers. 99 00:06:38,440 --> 00:06:41,080 Speaker 1: As New Orleans rebuilt from the disaster, some of these 100 00:06:41,120 --> 00:06:45,279 Speaker 1: concerns were addressed. The Army Corps Engineers designed a system 101 00:06:45,279 --> 00:06:48,400 Speaker 1: of floodwalls and levees snaking three hundred and fifty miles 102 00:06:48,600 --> 00:06:52,200 Speaker 1: that's five hundred and fifty kilometers through five parishes, at 103 00:06:52,200 --> 00:06:56,919 Speaker 1: a cost of over fourteen billion dollars. However, that was 104 00:06:57,000 --> 00:07:00,360 Speaker 1: now twenty years ago and maintenance is an ongoing issue. 105 00:07:00,480 --> 00:07:03,479 Speaker 1: They estimate that it'll cost another billion dollars in upkeep 106 00:07:03,520 --> 00:07:06,320 Speaker 1: over the next fifty years, and that kind of funding 107 00:07:06,520 --> 00:07:11,200 Speaker 1: is frustratingly hard to come by. The Netherlands faced a 108 00:07:11,200 --> 00:07:15,320 Speaker 1: similar situation following the flood in nineteen fifty three. In 109 00:07:15,360 --> 00:07:18,080 Speaker 1: the decades that followed, engineers set out to build a 110 00:07:18,120 --> 00:07:21,840 Speaker 1: new kind of barrier against the sea. They steadily replaced 111 00:07:21,880 --> 00:07:24,040 Speaker 1: the old dike system which had been in place since 112 00:07:24,080 --> 00:07:27,880 Speaker 1: the medieval ages, and created, weirdly enough, right around three 113 00:07:27,960 --> 00:07:30,640 Speaker 1: hundred and fifty miles of what many consider the safest 114 00:07:30,720 --> 00:07:34,920 Speaker 1: levee system in the world. They started by reevaluating their 115 00:07:35,040 --> 00:07:39,000 Speaker 1: entire system in several key ways. They set out thinking 116 00:07:39,080 --> 00:07:43,679 Speaker 1: long term, like really long term, new orleands. Old levees 117 00:07:43,680 --> 00:07:45,800 Speaker 1: were built to with stand the strongest possible storm in 118 00:07:45,840 --> 00:07:50,320 Speaker 1: two hundred years. Netherlands engineers designed a system strong enough 119 00:07:50,360 --> 00:07:53,000 Speaker 1: to match the kind of catastrophic storm that only occurs 120 00:07:53,120 --> 00:07:58,320 Speaker 1: once in ten thousand years. Also, instead of constructing increasingly 121 00:07:58,320 --> 00:08:02,080 Speaker 1: bigger solid barriers like levees and flood walls, they sought 122 00:08:02,080 --> 00:08:05,800 Speaker 1: to create better ways of absorbing floodwaters in marsh plains 123 00:08:05,960 --> 00:08:10,800 Speaker 1: and specially constructed rivers. In some cases, this involved setting 124 00:08:10,880 --> 00:08:15,120 Speaker 1: dikes farther back from the water. The engineers also developed 125 00:08:15,160 --> 00:08:19,600 Speaker 1: tough synthetic textiles to better anchor earth than levees These 126 00:08:19,600 --> 00:08:23,720 Speaker 1: prevent soil movement and water penetration. The New Lands Levee 127 00:08:23,760 --> 00:08:29,280 Speaker 1: system began using this technology following Hurricane Katrina. The Netherlands 128 00:08:29,320 --> 00:08:33,400 Speaker 1: also implemented more stringent and centralized control and maintenance of 129 00:08:33,440 --> 00:08:36,920 Speaker 1: their dikes and now use automated surveillance systems to keep 130 00:08:36,960 --> 00:08:39,800 Speaker 1: an eye on how their levees are holding up. They 131 00:08:39,840 --> 00:08:43,160 Speaker 1: installed fiber, optic and electronic sensors in dike structures to 132 00:08:43,200 --> 00:08:47,160 Speaker 1: report changes back to a central monitoring system. The several 133 00:08:47,160 --> 00:08:51,959 Speaker 1: other systems monitor water pressure and water level. A major 134 00:08:52,080 --> 00:08:56,200 Speaker 1: challenge in maintaining levee systems in urban areas is urban sprawl, 135 00:08:56,440 --> 00:09:01,280 Speaker 1: which can place increased pressure on existing levee structures. Levees 136 00:09:01,320 --> 00:09:05,720 Speaker 1: require regular maintenance, constant monitoring, and a long term appreciation 137 00:09:05,960 --> 00:09:10,640 Speaker 1: for how rivers, oceans, and storms behave. When these are 138 00:09:10,640 --> 00:09:14,040 Speaker 1: in place, communities can thrive safely along the beauty and 139 00:09:14,120 --> 00:09:18,360 Speaker 1: convenience of coastal and riverside areas. It's when we fail 140 00:09:18,440 --> 00:09:26,760 Speaker 1: to remember this that rivers and oceans become destroyers. Today's 141 00:09:26,760 --> 00:09:29,080 Speaker 1: episode is based on the article what is a levee? 142 00:09:29,120 --> 00:09:31,920 Speaker 1: On HowStuffWorks dot com, written by Marshall Brain and Robert 143 00:09:32,000 --> 00:09:35,040 Speaker 1: Lamb brain Stuff is production of iHeartRadio in partnership with 144 00:09:35,080 --> 00:09:37,640 Speaker 1: how stuffworks dot Com and is produced by Tyler Klang. 145 00:09:38,160 --> 00:09:41,280 Speaker 1: Four more podcasts from my heart Radio. Visit the iHeartRadio app, 146 00:09:41,360 --> 00:09:44,200 Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.