TheYellowRiverorHuangHe/HwangHoisthesecond-longestriverinChinaandthesixth-longestintheworldat5,464kilometers.OriginatingintheBayanHarMountainsinQinghaiProvinceinwesternChina,itflowsthroughnineprovincesofChinaandemptiesintotheBohaiSea.TheYellowRiverbasinhasaneast-westextentof1900kmandanorth-southextentof1100km.Totalbasinareais742,443km². 　　TheYellowRiveriscalled"thecradleofChinesecivilization",asitsbasinisthebirthplaceofthenorthernChinesecivilizationsandwasthemostprosperousregioninearlyChinesehistory.Butfrequentdevastatingfloodinglargelyduetotheelevatedriverbedinitslowercourse,hasalsoearnedittheunenviablename"China'sSorrow". 　　EarlyChineseliteraturereferstotheYellowRiversimplyasHe(河),thewordthathascometomeansimply"river"inmodernlanguage.Thefirstappearanceofthename"YellowRiver"(黄河)isintheBookofHan(Chinese:汉书;)writtenintheWesternHandynasty(206BC–AD9).Thename"YellowRiver"describestheperennialochre-yellowcolourofthemuddywaterinthelowercourseoftheriver.Theyellowcolorcomesfromloesssuspendedinthewater. 　　SometimestheYellowRiverispoeticallycalledthe"MuddyFlow"(simplifiedChinese:浊流).TheChineseidiom"whentheYellowRiverflowsclear"isusedtorefertoaneventthatwillneverhappenandissimilartotheEnglishexpression"whenpigsfly". 　　Characteristics 　　TheYellowRiverisnotableforthelargeamountofsiltitcarries—1.6billiontonsannuallyatthepointwhereitdescendsfromtheLoessPlateau.Ifitisrunningtotheseawithsufficientvolume,1.4billiontonsarecarriedtotheseaannually. 　　Inmoderntimes,since1972whenitfirstdriedup,theriverhasdriedupinitslowerreachesmanytimes,fromJinantotheseainmostyears,in1997for226days.Thelowvolumeisduetoincreasedagriculturalirrigation,byafactoroffivesince1950.Waterdivertedfromtheriverasof1999served140millionpeopleandirrigated74,000km²ofland.Thehighestvolumeoccursduringtherainyseason,fromJulytoOctober,when60%oftheannualvolumeoftheriverflows.MaximumdemandforirrigationisneededbetweenMarchandJune.Inordertocaptureexcesswaterforusewhenneeded,andforfloodcontrolandelectricitygeneration,severaldamshavebeenbuilt,butduetothehighsiltloadtheirlifeisexpectedtobelimited.AproposedSouth-NorthWaterTransferProjectinvolvesseveralschemestodivertwaterfromtheYangtzeRiver,oneinthewesternheadwatersoftheriverswheretheyareclosesttooneanother,anotherfromtheupperreachesoftheHanRiver,andathirdusingtherouteoftheGrandCanal. 　　DuetoitsheavyloadofsilttheYellowRiverisadepositingstream,thatis,itdepositspartofitscarriedburdenofsoilinitsbedinstretcheswhereitisflowingslowly.Thesedepositselevatetheriverbedwhichflowsbetweennaturalleveesinitslowerreaches.Shouldafloodoccur,therivermaybreakoutoftheleveesintothesurroundinglowerfloodplainandadoptanewcourse.Historicallythishasoccurredaboutonceeveryhundredyears.Inmoderntimes,considerableefforthasbeenmadetostrengthenleveesandcontrolfloods. 　　TheYellowRiverdeltatotals8,000squarekilometers.However,since1996ithasbeenreportedtobeshrinkingslightlyeachyearthrougherosion.