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New Orleans has only gradually resurrected itself after the city drown five years ago this hebdomad postdate Hurricane Katrina . That process echo an unpleasantly familiar dramatic play that has played out unnumberable time around the world during human history .
build on the coasts and near the rich floodplain of a river has allow closure access to water for barter and agriculture since the earliest years of Egypt and Mesopotamia , according to Greg Aldrete , a historian at the University of Wisconsin in Green Bay . That pick has often come back to obsess people when thefloodwaters rose .
In late July 2010, flooding caused by heavy monsoon rains began in several regions of Pakistan, including the Khyber Pakhtunkhwa, Sindh, Punjab and parts of Baluchistan.
" That tensity has existed since the very dawn of civilisation , " Aldrete tell LiveScience . " People be given to build city in floodplains . " [ Graphic : What Happened in New Orleans ]
catastrophe has often watch , even if none has quite rivaled the biblical flood which fructify Noah ’s ark afloat . The Mississippi River broke through the levee and send away hundreds of thousands of Americans in seven states in 1927.Chinahas historically suffered great exit of life through floods , including the 1931 implosion therapy of the Yellow River that may have killed millions .
homo have tried to control the water with levees and dams , essentially rerouting Mother Nature using a complex mesh of barriers . But the most monumental engine room labor can often lead to even more complex problems , experts say – particularly if deviser fail to prepare for the worst . And then there ’s the expense , as some vulnerable town and cities just ca n’t afford a massive technology labor to keep out floodwaters in some future storm .
Leaking levees
Levees did not carry through New Orleans during the extreme events of 2005 , whenHurricane Katrinaonly sideswiped the metropolis rather than strike it instantly . Now the U.S. Army Corps of Engineers labors to build an all-encompassing system of defenses to interchange what had been " a organisation in name only , " concord to its written report on the Katrina catastrophe .
Other concerns exist for the 1,600 sea mile ( 2,574 kilometers ) of earthen levees protecting the metropolis of Sacramento , Calif. , a sprawl inland community with extensive suburbs all situated at the concourse of the Sacramento and American river . The older organization requires both repairs and upgrades to get it up to current design standards , said Tom Brandon , a polite and environmental applied scientist at Virginia Tech .
Scientific reports have characterized Sacramento , the state ’s working capital , as a catastrophe waiting to chance next clock time a major overflow strikes .
" The consequences of loser there are great – perhaps jillion of dollars of damage , " Brandon said .
Those consideration add up at a time when many part around the world have been stricken by overflow . Surging waters have run aground or displaced millions of the great unwashed in hard - hit Pakistan , China and Niger during August alone .
When the levee do n’t subsist
This calendar month has spelled bad news program for many U.S. communities as well . For instance , the 56,000 - person Ithiel Town of Ames , Iowa endured record flood levels as water overflow from Squaw Creek and the South Skunk River in early August .
Both watercourse eventually lead to the Mississippi River , where an wide system of privately owned levees keep the floodwaters contained — at least some of the time . But Ames has no protective levees besides instinctive sediment buildup or arouse roads , said William Simpkins , a hydrogeologist at Iowa State University .
As a result , many Ames building on the local floodplain were underwater . Some commercial enterprise such as Happy Joe ’s Pizza have given up after the recent flood lamp damage , Simpkins order . The pizza pie parlor had built a small paries to protect itself against the1993 alluvion horizontal surface , but to no avail .
The local Wal - Mart and Target both survive because they had raised their reason levels above the " 100 - year flood plain , " but that present too expensive a root for most of the town .
Of course , nobody even knows if the belated flooding represents a 100 - year consequence or a 500 - yr result , Simpkins said . The terminus 100 - year flood itself can also become shoddy .
" I conceive people are under the illusion that if there ’s a 100 - year flood one year , you ’re not going to have one the next year , " Simpkins order LiveScience . " But in 2008 there was a great flood , and the one a few weeks ago was even bigger . "
Levees or even a dike might help verify next implosion therapy . But Simpkins say that taxpayers may balk at the disbursal , and pointed out that existing dams face criticism about how well they manage water stage .
" Better plan on the flood plain and incentives for concern to move to high primer might be crummy in the long running game than building a multimillion - dollar decametre , " Simpkins said .
Flood - control complication
Plenty of dams exist in the Western United States for managing water supplies and generating electricity , along with flood control . But big problems keep company big dams , said John Byrne , director of the University of Delaware ’s Center for Energy and Environmental Policy .
Many business have focused late on the world ’s largest dam in China . The multibillion - dollar mark Three Gorges Dam has faced exceptional flooding on the Yangtze River , which has experts watching for signs of trouble this class .
" The dam has had difficulty dealing with the volume , " Byrne explicate . " They have had to institute hold in sack that then flood the downstream areas to prevent the decameter from being in a hazardous condition . "
That have in mind the dam can regulate the amount of floodwaters expel at a pay time , but implosion therapy still hits people and homes downstream . It has also track down into trouble because of river silt clogging the turbine that sire electrical energy for China ’s easterly cities .
As an alternative , China could have built a telephone number of smaller , regionally - sharpen dams , Byrne read . Such dams could have released water without the eminent flood levels that accompany the Three Gorges Damreleases .
Smaller dams would not have supplied China ’s eastern metropolis with as much electrical energy , but could have allow for electrification to local regions .
Taiwanese functionary had first claimed that theThree Gorges Dam"could fend off the worst deluge in 10,000 years " in a report go forth in June 2003 . That title has been descale back to " the worst flood in 100 years " within a more late report issued in October 2008 , according to the ChinesePeople ’s Daily .
The World Commission on Dams has already begun reconsidering the consequences of using dams as flood lamp control , Byrne said .
" Anytime you endeavor to engineer a river on this great musical scale , you ’ll have an encroachment that is problematic , " Byrne said .
echo of the yesteryear
Many flood - control problem of today look eerily familiar to Aldrete , the University of Wisconsin historian . He completed a book titled " Floods of the Tiber in Ancient Rome " ( Johns Hopkins University Press , 2007 ) just a workweek before Hurricane Katrina struck New Orleans .
Rome has a unique diachronic track record over 3,000 years as a huge ancient city that live frequent urban implosion therapy . Several weeks of rainfall would saturate the filth and go to overflow from the Tiber River . That caused ruinous flooding every 20 or 25 years , and raised water level by 50 base ( 15 meters ) .
" Even though [ the Romans ] had the resources and applied science knowledge to really make the urban center safe from floods , they never did , " Aldrete sound out . " Instead , they pursued a whole bunch of flood - control strategies sporadically . "
About 86 percent of the wealthy Romans built their home on the hills border the city . The piteous people dwell below could also scramble up onto the J. J. Hill during floods , and so decease rates typically did not get very high .
The Romans also bit by bit rear the ground level for the Roman Forum that served as the mall of civic life-time . They dumped ten-spot of thousands of tons of shit over a period of 500 years until the domain sit about 33 feet ( 10 m ) above its original level .
Crucially , the Romans installed the city ’s much - admire sewers that served first and foremost to drain away all the superfluous pelting and floodwaters . That has modern Echo , such as Tokyo ’s G - Cans Project , a monolithic undercover connection of tunnels that protects the Nipponese city against implosion therapy during heavy rain and typhoons .
" That ’s really what the Roman sewers are – technically they ’re storm drains , " Aldrete said . " They are a practiced position to dump sewerage , but the main intellect for them was to enfeeble away water . "
rinsing and repetition
Ancient Rome had some additional advantages over modern urban center when it come to floods . building such as the Colosseum had thick wall and self-coloured substructure that resist floodwaters better than many modern structures with narrow wall and shallow foundations .
Conveniences such as electrical energy also make mod construction more vulnerable to flood damage , Aldrete place out .
Finally , Rome had its raised aqueduct arrangement that get overbold weewee into the city from 20 to 50 miles ( 32 to 80 klick ) away . That protected the drink body of water from pollution , whereas swamp in advanced metropolis often forget filth choking the filtration plants or wells .
Rome finally disembarrass itself of most major floods by constructing embankment along the Tiber River in the late 1800s . That has free modern Romans from have to adopt the more matter - of - fact posture that ancient Romans had towardnatural disasters .
But Aldrete still wish to steer to a diachronic moment where the Roman Senate deliberate whether to prevent succeeding floods by diverting upstream affluent of the Tiber River , back when the river was look at a god .
" In the close they vote to do nothing , because they did n’t want to fall the loftiness of the Tiber River , " Aldrete say .
