Hurricane Harvey and its remainder have make do to dump likelyrecord - settingamounts of rain across Texas . The Weather Channel expect that some locations could see accumulation totality of 50 column inch before the conditions at long last allow up . Some locating around and outside of Houston have already have seen floodshigher than 15 human foot .
You might feel uninitiated ask it , but reporting on event like this run to leave out one of the most basic interrogation : how two foot of rain becomes ten feet of implosion therapy . On one point the answer is bare , that water flows from higher orbit to lower areas . But complex hydrodynamics and Houston ’s geographics can lead to even more extremes , which helps explicate why things are looking so terrible — and will in all likelihood remain that way for a while .
“ This water could be hanging around there literally for weeks , ” Barry Keim , Louisiana State Climatologist at Louisiana State University , told Gizmodo .
Flooding pass off when water conglomerate in an domain faster than it can drain , from rain , oceans , or even broken dike , fit in tothe NOAA ’s National Severe Storms Laboratory . That water moves to the lowest lying area in the region , like river and brook , and then flows down hill . You ’ve also probably find out that Houston is quite plane — that signify that the water ca n’t drain as quickly , and stays moribund in already - flooded areas .
Keim explained that this stagnation can conduct to a pileup from other factors . Normally , small stream trickle into bombastic and larger rivers , like a electronic web of branch combine into a large automobile trunk . But when the independent trunk accumulates too much pee , these tributaries can begin to back up , as go on last yearin Baton Rouge , Louisiana . “ When you have a glut of weewee in all the main arteries , it has nowhere to go , ” he said . “ It just sit down there and might back up and create gamy water like that . ”
Houston specifically drains via a bayou system , a flat system of slow - move river or pee on flooded landed estate , John Nielsen - Gammon , the Texas State Climatologist at Texas A&M University , explained to Gizmodo . This head to additional challenge , on top of the fact that it ’s a city full of concrete and paving , imperviable surface that water system ca n’t seep into . holey soil would normally let the water run out more speedily than concrete . AsProPublica reportedlast twelvemonth , Houston already floods frequently , as its lightning - fast , jolly un - zone economical development replaced prairie with pavement . That report card found that even sphere outside of flood plain , which are purportedly unlikely to flood , have face implosion therapy in 2009 , 2015 , and 2016 .
Storm upsurge is often responsible for for coastal implosion therapy , but is not a major contributor to Houston ’s flood problem from Harvey , Nielsen - Gammon severalize Gizmodo . ( Although the National Hurricane Center has reportedsome surgesin Galveston Bay . ) And the rainfall is still historic . “ In term of its impact on individual locations , it ’s probably something like one in a 500 to one in 1000 year event , ” he said , and bring that it could potentially be the gravid amount of rain over such a large field .
The moral is , five to ten inches of rainwater might mean only a little implosion therapy for higher areas , but anyone on lower ground is getting everyone else ’s rain , too . And once the pee has arrived on flavourless earth , it ’s there to stay on . “ There ’s nothing to do at this microscope stage but wait it out , ” Keim say .
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