给水排水专业英语课件(李田)6

PartⅡWaterSupplyUnit6WaterSupplySystemNewwordsandexpressionspurificationn.净化提纯vt.purifyworksn.工厂构筑物pipenetworkn.管网管道系统distributionsystemn.配水系统分配系统mainn.干管干线kilopascaln.千帕斯卡ubiquitousadj.到处存在的,(同时)普遍存在的waterconsumptionn.用水量耗水量emergencyn.紧急情况,突然事件Newwordsandexpressionsbackupn.储备备份回溯vt.做备份emergencybackup紧急情况的储备plumbingn.管道工程室内管道系统Aplumberisapersonwhofitsandmendstheplumbing.meteragen.计量seweragen.排水系统污水percapita每人按人数平均watermeter水表leakn.漏出物，泄漏，漏洞vi.泄漏theroofleakssocioeconomicadj社会经济学的dwellingn.住宅住处Thenatureofthewatersourcecommonlydeterminestheplanning,design,andoperationofthecollection,purification,transmission,anddistributionworks.1-1Thetwomajorsourcesusedtosupplycommunityandindustrialneedsarereferredtoassurfacewaterandgroundwater.Streams,lakes,andriversarethesurfacewatersources.Groundwatersourcesarethosepumpedfromwells.1-2Fig.2-1depictsanextensionofthewaterresourcesystemtoserveasmallcommunity.Thesourceineachcasedeterminesthetypeofcollectionworksandthetypeoftreatmentworks.2-1Source(watershed)divideCollectionworks(Reservoir)TransmissionworksTreatmentworks(FiltrationPlant)DistributionSystemTreatmentworks(Softeningplant)orIronRemovalPlantStorageReservoirCollectionworks(Wellfield)Source(Groundwater)MixingandflocculationSedimentationFiltrationDisinfectionThepipenetworkinthecityiscalledthedistributionsystem.Thepipesthemselvesareoftenreferredtoaswatermains.Waterinthemainsgenerallyiskeptatapressurebetween200and860kilopascals(kPa).Excesswaterproducedbythetreatmentplantduringperiodsoflowdemand(usuallythenighttimehours)isheldinastoragereservoir.2-2Thestoragereservoirmaybeelevated(theubiquitouswatertower),oritmaybeatgroundlevel.Thestoredwaterisusedtomeethighdemandduringtheday.Storagecompensatesforchangesindemandandallowsasmallertreatmentplanttobebuilt.Storageisalsousedtoprovideemergencybackupincaseofafire.2-3Populationandwaterconsumptionpatternsaretheprimefactorsthatgovernthequantityofwaterrequiredandhencethesourceandthewholecompositionofthewaterresourcesystem.3-1Oneofthefirststepsintheselectionofasuitablewatersupplysourceisdeterminingthedemandthatwillbeplacedonit.Theessentialelementsofwaterdemandincludetheaveragedailywaterconsumptionandthepeakrateofdemand.3-2Theaveragedailywaterconsumptionmustbeestimatedfortworeasons:(1)todeterminetheabilityofthewatersourcetomeetcontinuingdemandsovercriticalperiodswhensurfaceflowsareloworgroundwatertablesareatminimumelevations;and(2)forpurposesofestimatingquantitiesofstoredwaterthatwouldsatisfydemandsduringthesecriticalperiods.3-3Thepeakdemandratesmustbeestimatedinordertodetermineplumbingandpipesizing,pressurelosses,andstoragerequirementsnecessarytosupplysufficientwaterduringperiodsofpeakwaterdemand.3-4Manyfactorsinfluencewateruseforagivensystem.Forexample,themerefactthatwaterunderpressureisavailablestimulatesitsuse,oftenexcessively,forwateringlawnsandgardens,forwashingautomobiles,foroperatingair-conditioningequipment,andforperformingmanyotheractivitiesathomeandinindustry.4-1Thefollowingfactorshavebeenfoundtoinfluencewaterconsumptioninamajorway:1.Industrialactivity;2.Meterage;3.Systemmanagement;4.Standardofliving;5.Climate.4-2Thefollowingfactorsalsoinfluencewaterconsumptiontoalesserdegree:extentofsewerage,systempressure,waterprice,andavailabilityofprivatewells.Theinfluenceofindustryistoincreasepercapitawaterdemand.5-1Smallruralandsuburbancommunitieswilluselesswaterperpersonthanindustrializedcommunities.Industryisprobablythelargestsinglefactorinfluencingpercapitawateruse.5-2Thesecondmostimportantfactorinwateruseiswhetherindividualconsumershavewatermeters.Meterageimposesasenseofresponsibilitynotfoundinunmeteredresidencesandbusinesses.6-1Thissenseofresponsibilityreducespercapitawaterconsumptionbecausecustomersrepairleaksandmakemoreconservativewater-usedecisionsalmostregardlessofprice.Becausewaterissocheap,priceisnotmuchofafactor.6-2Followingmeteragecloselyistheaspectcalledsystemmanagement.Ifthewaterdistributionsystemiswellmanaged,percapitawaterconsumptionislessthanifitisnotwellmanagedmanaged.7-1Well-managedsystemsarethoseinwhichthemanagersknowwhenandwhereleaksinthewatermainsoccurandhavethemrepairedpromptly.7-2Industrialactivity,meterage,andsystemmanagementaremoresignificantfactorscontrollingwaterconsumptionthanareeitherthestandardoflivingortheclimate.Therationaleforthelattertwofactorsisstraightforward.Percapitawateruseincreaseswithanincreasedstandardofliving.8-1Highlydevelopedcountriesusemuchmorewaterthanthelessdevelopednations.Likewise,highersocioeconomicstatusimpliesgreaterpercapitawaterusethanlowersocioeconomicstatus.Higheraverageannualtemperatureimplieshigherpercapitawateruse,whereasareasofhighrainfallexperiencelowerwateruse.8-2TheaveragenationalvalueforwaterconsumptionintheUnitedStatesin1970was628literspercapitaperday(Lpcd).Asimilarstudyconductedin1954yieldedavalueof556Lpcd.Theaveragesingle-familyresidenceusesabout208L/d.9-1Thevariationindemandisnormallyreportedasafactoroftheaverageday.Formetereddwellingsthefactorsareasfoll