IELTSWritingTask1:'flooddiagram'answer
Thediagramsbelowshowhowhousescanbeprotectedinareaswhicharepronetoflooding.
Here'smyfullband9report:
Thediagramsparetwodifferentmethodsofdefenceforhomeswhichareatriskofbeingflooded.
Thekeydifferencebetweenthediagramsisthattheyshowfloodprotectionwithandwithoutastopbank.Ineithercase,theat-riskhomeisraisedonstiltsabovegroundlevel.
Thefirstdiagramshowshowastopbankactsasafloodbarriertostopriverwaterfromfloodinghomes.Thestopbankisasmallmoundoflandnexttotheriverthatishigherthanthe100-yearfloodlevel,andpreventstheriverfromburstingitsbanks.Nearbyhousescanbebuiltonstiltstopreventfloodingfromrainwater,andafloodgatebeneaththestopbankcanbeopenedtoallowthis‘ponding’todrainoffintotheriver.
Whenthereisnostopbank,asshownintheseconddiagram,therewillbenothingtostoptheriverfromflooding.Inthiscase,thesolutionistoputbuildingsonstilts.Theheightofthestiltsismeasuredsothatthefloorofthehouseis300mmabovethe100-yearfloodlevel.Thismeasurementiscalledthe‘freeboard’.
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