搜索
水利水电工程专业英语——河流工程篇1.SomeProblemsRelatedtoAlluvialRivers（1）1.与冲积河流相关的一些问题（1）Manyoftheearliercivilizationscameintobeingthefertilevalleysoflargerivers.CivilizationsprosperedintheNilevalleyinEgypt,alongtheTigrisandEupharatesriversinMesopotamia,alongtheIndusRiver.Asearlyas4000B.C.peoplebuiltdamsacrosstheriverstostorewater,dugcanalsfornavigationpurposesandalsotocarrywatertothefieldstoproducemuch-neededfood.Togetherwiththeproblemsassociatedwiththeirrigationworks,theseearliercivilizationswereconfrontedwiththeproblemsoffloodcontrolandtheChinesehaddevelopedexcellentsystemsofdikesfortheprotectionofinhabitedareasagainstfloods.很多早期的文明都孕育在大江大河的肥沃的河谷。这些文明繁荣在在埃及尼罗河谷，沿着美索不达米亚的底格里斯河和幼发拉底河，沿着印度河流域。早在公元前4000年，人们就横跨河流修建水坝来蓄水，以航运及将水带到农田以生产更加非常需要的事物为目的而开挖渠道。与同灌溉工程相关的问题一样，这些早期文明也面临着防洪的问题，而中国人则已经发展了防洪保护居住区的优秀堤防体系。Thus,sincethedawnofcivilization,mankindhasfacedproblemsassociatedwithrivers,andsolvedthemtothebestoftheirability.Morecomplicatedproblemsareencounteredinmoderntimesbecause,withtheincreaseinpopulation,moreandmoreriversarebeingharnessedformultipurposeuse-floodcontrol,watersupply,powergeneration,irrigationandnavigation-forwhichartificialchangesarebeingmadeinthewatercourses.Theseproblemshavebecomecomplicatedbecauseofthefactthatriversandotherwatercourses,inmostcases,runthroughloosematerialandthewatercarriessomeofthismaterialalongwithit.Thepresenceofsedimentinwateralsocreatesproblemsintheoperationofturbinesandpumpsthroughwiththesediment-ladenwaterflows.Furtherthemoneyspentintreatingthewatertoremovesedimentandmakeitfitfordomesticorindustrialconsumptionisenormous.Otherproblemsconnectedwiththetrainingandharnessingofriverscarryingsedimentalsoengagetheattentionofalargenumberofengineers.Infactifthewatercoursesweretoflowthroughnonerodiblematerial,manyoftheaboveproblemswouldnotexist.因此，自文明的曙光出现开始时，人类就已经面临着与河流相关的问题，并尽其最大可能解决问题。现代社会则遇到了更加复杂的问题，因为随着人口的增加，越来越多的河流因为多种目的的利用而被开发利用，如防洪、供水、发电、灌溉及航运，河道正被人为地改变。这些问题已经变得复杂因为在大多数情况下，这些河流和其他河道流过松散介质并携带这些材料于其中。水中泥沙的存在也通过含沙水流的流动而为水轮机和水泵的操作带来了问题。而且在处理水流以去除泥沙并使之适合家庭使用以及工业耗水的费用是巨大的。其他与整治和开发利用含沙河流相关的问题也吸引了大量工程师的注意力。事实上，如果河道流过非侵蚀性材料，那么上述的很多问题就不会存在了。TheloosenoncohesivematerialthroughwhichariverflowsisgenerallycalledsedimentandthesubcommitteeonSedimentTerminologyoftheAmericanGeophysicalUnionhasacceptedthefollowingdefinitiongivenbytheNewStandardDictionary:Fragmentalmaterialtransportedby,suspendedin,ordepositedbywaterorair,oraccumulatedinthebedsbyothernaturalagents;anydetritalaccumulation,suchasloess.河流流过的松散的非粘性材料通常被称为沉积物，并且美国地球物理学联合会泥沙术语小组委员会已经接受了《新标准词典》中给出的如下定义：水流或空气中输运的、悬浮其中或储存于其中的碎屑材料，或者在河床中累积的其他天然材料；任何碎屑积聚，比如黄土。Ordinarilythisdoesnotincludeice,logsofwood,ororganicmaterialfloatingonthesurface.Sedimentisalsosometimesknownasalluvium.Thatbranchofengineeringwhichdealswithriversandcanalsflowingthroughloosetransportablematerial(sedimentoralluvium)andtransportingsomeofitalongwithwateriscalledfluvialhydraulics,sedimentengineeringoralluvialriverdynamics.Thesechannelsorriversarecalledalluvialchannelsoralluvialrivers.通常这并不包括冰、原木或者在表面漂浮的有机材料。沉积物有时也称为冲积土。处理流过松散可输运材料（沉积物或冲积物）并随着水流携带其中一些材料的河流和渠道的工程分支被称为河流动力学，泥沙工程或冲积河流动力学。这些渠道或河流被称为冲积渠道或冲积河流。Civilengineersassociatedwithwaterresourcesdevelopmentcomeacrossvarioustypesofproblemsrelatedtoalluvialriversandchannels.Someoftheseimportantproblemsarebrieflydiscussedinthefollowingparagraphstogivethereaderaperspectiveandscopeofthefield.与水资源开发相关的土木工程遇到与冲积河流和渠道相关的很多种问题。以下各段简要地讨论了这里的一些重要问题，以为读者提供该领域的背景和范围。1.1SedimentCharacteristics1.1泥沙特性Sedimentsarebroadlyclassifiedascohesiveandnoncohesive.Cohesionmayfaroutweightheinfluenceofthephysicalcharacteristicsoftheindividualparticles.Noncohesivesedimentparticlesreacttofluidforcesandtheirmovementisaffectedbythephysicalpropertiesoftheparticlessuchassize,shape,densityandsettlingvelocity.Also,sedimentcharacteristicsmaychangethroughchemicalorphysicalreactions.沉积物被广泛地分类为粘滞性和非粘滞性。凝聚力可能远大于的单个颗粒的物理特性的影响。非粘性沉淀颗粒对流体力和其运动的反映由颗粒的物理性质，如大小、形状、密度和沉降速度的影响。同时，沉积物特性可能通过化学或物理反应而变化。1.2SedimentTransport1.2泥沙输运Aswaterflowsthroughriversandchannels,itcarrieswithitsomesediment.Partofthesedimentisdraggedorrolledalongthebedorisformostofthetimeincontactwiththebed.Thisisnamedasbedload.Theotherpartissuspendedinwaterandtravelswithapproximatelythesamevelocityaswater.Thisiscalledsuspendedload.Theamountofsedimentcarriedbytheriverorchannelisoneofthemostimportantvariablesinallsedimentproblems.Theextremelylargevariationinsedimentconcentrationisanindicationofthelargenumberoffactors,whichinfluencethesedimenttransportrateinalluvialstreams.Infactthesedimenttransportrateisaffectedbyhydrologicalaswellashydrauliccharacteristics.随着水流流过河流和渠道，它便携带泥沙。部分泥沙是沿着河流拖动或滚动，或者大部分时间与河床相接处。这被称为推移质。另外一部分悬浮在水流中并大致以与水流相同的速度移动。这被称为悬移质。河流或渠道所携带的泥沙量是在所有泥沙问题中最重要的变量之一。含沙量的非常大的变化指示着大量因素，这影响着冲积型河流中泥沙输运速度。事实上泥沙输运速度受到水文以及水力特性的影响。1.3RiverChannel1.3河道Theformationofanaturalstreamchannelisinfluencedbynumerousfactorsofclimate,geology,andgeography;themostimportantbeingthestreamdischarge,resistanceofthelandformstoerosion,geometricconfiguration,andthepropertiesandamountofthesedimenttransported.Theformanddimensionsofsuchachannel