Water-Management水资源管理课件.ppt

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1、Water ManagementOutlineHydrologic CycleWater Use CategoriesWater PollutionWastewater TreatmentWater Use PlanningThe Water IssuePhysical properties:Stores heat,for coolingActs as a solvent,carries wasteEvaporates when heated,hydrologic cycleWe careQuantityQuality,potable waterThe Water Issue-cont.70%

2、of earths surface is covered by waterFresh Water=3%Usable fresh water=.003%Water crisisDisproportion in distribution Increase in pop.Pollution intensify All water is locked into a constant recycling process-Hydrologic CycleRunoff-Surface water that moves across the surface of the land and enters str

3、eams and rivers.Groundwater-Water that fills spaces in the substrate.Water moves downward until it reaches an impervious layer of rock,and accumulates in porous layer called an aquifer.vWater Table-Top layer.vUnconfined Aquifer 自由（非承压）含水层自由（非承压）含水层 vConfined Aquifer 承压含水层承压含水层v(Artesian 自流自流)Unconfi

4、ned Aquifer-Usually near lands surface.Lower boundary is impermeable layer of clay or rock.Water is at atmospheric pressure and is recharged by rainfall and percolation 渗透渗透.Confined Aquifer-Bounded on top and bottom by impermeable layer-Water is stored under high pressure and is recharged from a ge

5、ologic recharge zone.Human influence on Hydrologic CycleOn evaporation:reservoir,cooling tower,irrigationOn infiltration:pave,sewerWater Withdrawal 取水取水Water Consumption 耗水耗水Water Withdrawal-Withdrawing water and then maybe returning it to its original source or consume.Water Consumption-Withdrawing

6、 water and incorporating it into a product,or otherwise moving it to another area so it does not make it back to its original source.Domestic useAgricultural useIndustrial useIn-stream use Water Use CategoriesDomesticNeed purification facilities or wells.N.A.400L/p.d,CHN.50150L/p.d.About 70%is retur

7、ned to rivers as wastewater.(solvent)More domestic water is wasted than consumed.Leakage 2050%.Natural purification processes cannot cope with highly concentrated wastes typical of large urban areas.As long as water is considered limitless and inexpensive,little effort will be made to conserve it.Ag

8、riculturalAbout 70%of water uses.Major consumptive use-irrigation.Increasing water costs will stimulate conservation Irrigation also requires a large amount of energy.i.e.pumpFour common irrigation methods:Surface/FloodvRequires extensive canal systems.SprayvMandates use of pumps.TricklevStrategical

9、ly placed openings.Sub-IrrigationvPipes can be used for drainage as well.IndustrialAbout 23%of water uses.90%of water used by industry is for cooling,and is returned to the source.Very little actually consumeddissipate and transport waste materials.Toxic and overload wastes lead stream and lake degr

10、adationprotect waters from pollution.Setting water quality standards for surface water.Limiting effluent discharges into the water.In-Stream UsesNon-consumptive.Major in-stream uses are hydroelectric power,recreation,and navigation.Presently,hydroelectric power plants produce 2.5%of world energy.Wat

11、er PollutionWater is considered polluted if a substance or condition is present that renders the water useless for a particular purpose.e.g.drinking water for humans is considered polluted(non-potable)if it contains pathogens or toxic substances.Analysis from source,pollutant and water body.Kinds of

12、 Water Pollutionsewage and animal manuresindustrial wastesoilradioactive substancessediments from soil erosionheatagricultural wastes including pesticidesPollutantsBODNutrientToxic chemicals AcidsDisease-causing organismsp363 Table 16.1Sources Point source:a definite source and place to enter water,

13、i.e.municipal and industrial discharge pipes.Non-point source:diffuse pollutant,i.e.road salt,acid rain.More difficult to identify and control.Municipal Water PollutionConsist of storm-water,water from industry,home and commercial establishment.Sewage:consists primarily of organic matter from garbag

14、e,food production,and human waste.Even small amount of harmful bacteria may cause disease epidemic.Coliform bacteria,generic term for bacteria found in human intestines,is not harmful but easy identified and related to amount of human waste entering system.Non-living organic matter presents a decay

15、problem.As micro-organisms metabolize organic matter,they use the available oxygen.Biochemical Oxygen Demand(BOD):Amount of oxygen required to decay a certain amount of organic matter.If too much organic matter is added,DO will be used up.Anaerobic bacteria respiration produce foal odor and unpleasa

16、nt taste.many detergents contained phosphates which contributed to Eutrophication.Excessive growth of algae and aquatic plants due to added nutrients.Eliminated from most major detergents since 1994.De-oxygenationAgricultural Water PollutionFertilizer contain phosphate results in aquatic eutrophicat

17、ion.Groundwater contamination by fertilizer and pestcides.Irrigation water carries a heavy load of salt.Water carry away dissolved nutrients to Factories and industrial complexes frequently dispose of waste in municipal sewage systems.Pollutants:organics,oil,metals,acids.May require special wastewat

18、er treatment.Often point sources.MiningChemical run-off.Acid mine drainage.Industrial Water PollutionThermal Pollution-occurs when water is withdrawn,used for cooling purposes,and then heated water is returned to its original source.An increase in temperature,even a few degrees,may significantly alt

19、er some aquatic ecosystems.Metabolism,DOElimination of cold-water speciesRelease is forbidden,substitute by three methods:large,shallow ponds,cooling tower,(water lost by evaporation)dry tower Marine Oil PollutionRunoff from streetImproper disposal of Lubricating oilLoading and unloading tanker1992-

20、New:Double-hulled vesselCurrently 15%accidentsGroundwater PollutionAgricultural productsUnderground storage tanksLandfills Septic tanksSurface impoundmentsWater Use Planning IssuesIncrease demand for high-quality water,unrestrained waste disposal and unlimited withdrawal of water lead to conflicts.M

21、etropolitan areas basic water services:Water supply for human and industryWatershed,upstream user Wastewater collection and treatmentStorm-water collection and managementSeparated or combined sewer systemFirst step:-Characterization of components in wastewaterDomesticmostly nutrients like C,N,and PI

22、ndustrialeach industry will be differente.g.pulp industry-mostly cellulosebrewing industry-mostly starchWastewater TreatmentRemoves large particles via filtration and then pumps remaining water into settling ponds and lakes.After settling,water is drawn off the topdevoid of large particulate matters

23、till has a heavy load of organic matter,dissolved salts,bacteria,and micro-organisms.A large receiving water is needed.Primary TreatmentSecondary TreatmentInvolves holding wastewater until organic matter has been degraded by biological process.Activated sludge sewage treatment or trickling filter sy

24、stem.Combination of primary and secondary treatment.Discharged water must still be disinfectedChlorine,UV,ozoneTertiary TreatmentSome plants now utilize an additional stage to remove even more dissolved pollutants i.e.phosphorous and nitrogen-extremely costly.Closed loop system-Out put of the wastew

25、ater plant becomes the input for drinking water supply.SalinizationAs plants extract water from the ground,salt content of the ground increases.Irrigation of arid farmland can make salinization more acute due to increased evaporation rates.Primarily a problem in areas under irrigation for several decades.Groundwater MiningMining of water refers to removing water from an aquifer faster than it can be replenished.Extended periods of mining can lead to land subsidence 沉降沉降,lowering of the water table(Beijing 40m)even salt-water intrusion of wells in coastal areas.Saltwater intrusion