Bài giảng Environmental Sciences - Chapter 7: Water

Chapter 7: WaterFigure 7-1 Earth’s water supply Problem: Fresh water availabilityKey FactsThe primary use for fresh water in U.S. is for agriculture.In our homes, we use the most fresh water to wash, clean, and flush.The typical person in an industrialized nation uses 700-1000 gallons per week! Figure 7-4 Condensation(The amount of water in the air)Human effects on the Hydrologic CycleFigure 7-3 The Hydrologic cycleFigure 7-6a Global air circulationFigure 7-6b Global air flow patternsRain shadowFigure 7-7 Rain shadowThe Ogallala AquiferFigure 7-16 Exploitation of an aquiferReasonable access to safe drinking water is defined as the availability of at least 20 liters per person per day from an improved source within 1 kilometer of the user's dwelling. Percentage of Population Without Reasonable Access to Safe Drinking Water 2008 with access to safe water, 1990 pg. 213Saltwater Intrusion Figure 7-18 Saltwater IntrusionMono LakeExcellent example of human interference with the water supply.The water in the lake was diverted from the lake to the city of Los Angeles. It became a salt bed.↑ Salt concentration due to evaporationAgricultureGreen Revolution- the introduction of high-yield grains to agriculture.High yield varieties are not ideal for subsistence farming because they need pesticides and chemical fertilizers.Sustainable- Crop rotation, variety of crops, animal wastes for fertilizer.The best, most effective way to solve world hunger is to help people provide for themselves.Water Quality testsNitratespHPhosphatesWhat do they tell you about your water?Figure 7-6c Global trade windsFigure 7-5 Global PrecipitationFigure 7-5 Global precipitation