英语翻译
Erosionisthewearingdownofalandscapeovertime.Itincludesthedetachment,transport,anddepositionofsoilparticlesbytheerosiveforcesofraindropsandsurfaceflowofwater.
Alandareacontainsrillsandchannels.Raindropimpactcandetachsoilparticlesonunprotectedlandsurfacesbetweenrillsandinitiatetransportoftheseparticlestotherills.Fromthesmallrills,theparticlesmovetolargerrills,thenintoephemeralchannelsandthenintocontinuouslyflowingrivers.Entrainmentanddepositionofparticlescanoccuratanypointalongthepath.Whenerosionoccurswithouthumaninfluence,itiscalledgeologicerosion.Acceleratederosionoccurswhenhumanactivityincreasestherateoferosion.
Erosionisamatterofconcerntowatershedandnaturalresourcemanagers.Twoofthemainreasonsreservoirsarebuiltarewatersupplyandfloodcontrol.Erosionupstreamofareservoirdepositssedimentinthebottomofthereservoirwhichlowersthereservoir’water-holdingcapacityandconsequentlyitsusefulnessforbothofthesepurposes.Thesoilsurfaceisthepartofthesoilprofilehighestinorganicmatterandnutrients.Organicmatterformscomplexeswithsoilparticlessothaterosionofthesoilparticleswillalsoremovenutrients.Excessiveerosioncandepletesoilreservesofnitrogenandphosphorusneededbyplantstogrowandextremeerosioncandegradethesoiltothepointthatitisunabletosupportplantlife.Iferosionissevereandwidespreadenough,thewaterbalanceofawatershedcanbealtered-rememberthatmostwaterislostfromawatershedviaevapotranspiration.