Water-Management水资源管理课件.ppt

1、Water ManagementOutline Hydrologic Cycle Water Use Categories Water Pollution Wastewater Treatment Water Use PlanningThe Water Issue Physical properties:Stores heat, for coolingActs as a solvent, carries wasteEvaporates when heated, hydrologic cycle We careQuantityQuality, potable waterThe Water Iss

2、ue- cont. 70% of earths surface is covered by water Fresh Water = 3% Usable fresh water = .003% Water crisis Disproportion 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

3、 of the land and enters streams 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

4、压含水层承压含水层v(Artesian 自流自流) Unconfined 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 unde

5、r high pressure and is recharged from a geologic recharge zone.Human influence on Hydrologic Cycle On evaporation: reservoir, cooling tower, irrigation On infiltration: pave, sewer Water Withdrawal 取水取水 Water Consumption 耗水耗水 Water Withdrawal - Withdrawing water and then maybe returning it to its or

6、iginal source or consume. Water Consumption - Withdrawing 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 use Agricultural use Industrial use In-stream use Water Use CategoriesDomestic Need purification fa

7、cilities or wells. N.A. 400L/p.d, CHN. 50150L/p.d. About 70% is returned 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 conside

8、red limitless and inexpensive, little effort will be made to conserve it. Agricultural About 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 /

9、FloodvRequires extensive canal systems.SprayvMandates use of pumps.TricklevStrategically placed openings.Sub-IrrigationvPipes can be used for drainage as well.Industrial About 23% of water uses. 90% of water used by industry is for cooling, and is returned to the source. Very little actually consume

10、d dissipate and transport waste materials. Toxic and overload wastes lead stream and lake degradation protect waters from pollution. Setting water quality standards for surface water. Limiting effluent discharges into the water.In-Stream Uses Non-consumptive. Major in-stream uses are hydroelectric p

11、ower, recreation, and navigation. Presently, hydroelectric power plants produce 2.5% of world energy.Water Pollution Water 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

12、-potable) if it contains pathogens or toxic substances. Analysis from source, pollutant and water body. Kinds of Water Pollutionsewage and animal manuresindustrial wastesoilradioactive substancessediments from soil erosionheatagricultural wastes including pesticides Pollutants BOD Nutrient Toxic che

13、micals Acids Disease-causing organisms p363 Table 16.1 Sources Point source: a definite source and place to enter water, 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 Pollution Con

14、sist of storm-water, water from industry, home and commercial establishment. Sewage: consists primarily of organic matter from garbage, food production, and human waste. Even small amount of harmful bacteria may cause disease epidemic. Coliform bacteria, generic term for bacteria found in human inte

15、stines, is not harmful but easy identified and related to amount of human waste entering system. Non-living organic matter presents a decay problem. As micro-organisms metabolize organic matter, they use the available oxygen. Biochemical Oxygen Demand (BOD): Amount of oxygen required to decay a cert

16、ain amount of organic matter.If too much organic matter is added, DO will be used up. Anaerobic bacteria respiration produce foal odor and unpleasant taste. many detergents contained phosphates which contributed to Eutrophication.Excessive growth of algae and aquatic plants due to added nutrients. E

17、liminated from most major detergents since 1994.De-oxygenationAgricultural Water Pollution Fertilizer contain phosphate results in aquatic eutrophication. Groundwater contamination by fertilizer and pestcides. Irrigation water carries a heavy load of salt.Water carry away dissolved nutrients to Fact

18、ories and industrial complexes frequently dispose of waste in municipal sewage systems. Pollutants: organics, oil, metals, acids. May require special wastewater treatment. Often point sources. Mining Chemical run-off. Acid mine drainage.Industrial Water Pollution Thermal Pollution - occurs when wate

19、r 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 alter some aquatic ecosystems. Metabolism, DO Elimination of cold-water species Release is forbidden, substitute by three methods: la

20、rge, shallow ponds, cooling tower, (water lost by evaporation) dry tower Marine Oil Pollution Runoff from street Improper disposal of Lubricating oil Loading and unloading tanker 1992 - New: Double-hulled vessel Currently 15% accidentsGroundwater Pollution Agricultural products Underground storage t

21、anks Landfills Septic tanks Surface impoundmentsWater Use Planning Issues Increase demand for high-quality water, unrestrained waste disposal and unlimited withdrawal of water lead to conflicts. Metropolitan areas basic water services: Water supply for human and industry Watershed, upstream user Was

22、tewater collection and treatment Storm-water collection and management Separated or combined sewer system First step:- Characterization of components in wastewater Domestic mostly nutrients like C, N, and P Industrial each industry will be different e.g. pulp industry - mostly cellulose brewing indu

23、stry - mostly starchWastewater Treatment Removes large particles via filtration and then pumps remaining water into settling ponds and lakes. After settling, water is drawn off the top devoid of large particulate matter still has a heavy load of organic matter, dissolved salts, bacteria, and micro-o

24、rganisms. A large receiving water is needed.Primary TreatmentSecondary Treatment Involves holding wastewater until organic matter has been degraded by biological process. Activated sludge sewage treatment or trickling filter system. Combination of primary and secondary treatment. Discharged water mu

25、st still be disinfected Chlorine, UV, ozoneTertiary Treatment Some 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 wastewater plant becomes the input for drinking water supply.Salini

26、zation As 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 Mining Mining 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