Presentation on theme: "LT 6E: Discuss the sustainability of freshwater resources"— Presentation transcript:
1 LT 6E: Discuss the sustainability of freshwater resources LT 6F: Identify possible solutions to the sustainability of freshwater resources and discuss the benefits and consequences of each..
2 Importance of Freshwater Necessary for life60% of us is composed of waterCould only survive a few days without itTakes huge amounts to supply us with food, energy etc..
3 Management of Freshwater Poorly managedCharged less than its worthHow would charging less than water’s worth contribute to the mismanagement of water?
4 Issues with water Global Economic National and global security issue EnvironmentalGlobal: Lack of access to safe drinking water in less developed countriesEconomic: vital for reducing poverty and producing food and energyNational and global security issue: increasing tensions both within and between nations over access to limited water resources they shareEnvironmental: Water loss/water pollutiondeclining water quality, lower fish populations, species extinctions and degradation of aquatic ecosystems
5 Availability of Freshwater Only about 0.024% of the planet’s water is available to us as liquid freshwaterSources:Groundwater depositsLakesRiversSteams
6 GroundwaterPrecipitation that seeps into the ground and moves downward through spaces in soil, gravel and rock until an impenetrable layer of rock stops it.Spaces deep in the earth hold more water than at the topZone of saturation: Deep; Completely filled with waterWater zone: top of this groundwater zoneAquifer: Deep; Groundwater flows through them; pumps used to bring water to surface; replenished mainly by precipitation
7 GroundwaterSurface water: freshwater from precipitation and melted snow that flows across the earth’s land surface and into lakes, wetlands, steams, rivers, estuaries, and into the ocean.Surface runoff: precipitation that does not infiltrate the groundWatershed (drainage basin): land from which surface water drains into a body of water
8 Reliable Runoff Usable 1/3 of surface runoff 2/3 lost by seasonal floodingWorld-wide averagesDomestic: 10%Agriculture: 70%Industrial use: 20%
9 Water Footprint Volume of water we directly and indirectly Average American uses 260 liters per dayFlushing toilets, 27%Washing clothes, 22%Taking showers, 17%Running faucets, 16%Wasted from leaks, 14%World’s poorest use 19 liters per day
10 Virtual Water Water is used indirectly Hamburger, 2400 litersVirtual water often exported/importedGrains and other foods
11 Water Shortages Main factors Dry climates Drought Too many people using a normal supply of waterWasteful use of water
12 Water Shortages More than 30 countries face water scarcity Rapid urbanization, economic growth and drought are expected to put more stress on water resources in developing countries like China and India30% earth’s land area experiences severe droughtWill rise to 45% by 2059 from climate changePotential conflicts/wars over waterRefugees from arid landsIncreased mortality
13 Think Box What do you think we can do to increase freshwater supplies? Reducing unnecessary wasteExtracting groundwaterBuilding dams and reservoirs to store runoff in riversTransporting surface water from one area to anotherConverting salt water to freshwater (desalination)
14 Extracting Groundwater AdvantagesDisadvantagesUseful for drinking and irrigationExists almost everywhereRenewable if not overpumped or contaminatedCheaper to extract than most surface waterAquifer depletion from overpumpingSinking of land from overpumpingPollution of aquifers lasts decades or centuriesDeeper wells are nonrenewableMore than have of the world’s population relies on aquifers for drinking waterOverpumping: Limits future food production, Bigger gap between the rich and the poor, Land subsidence (sinking),Groundwater overdrafts near coastal regions (Contamination of groundwater with saltwater)
15 Building Dams and Reservoirs Dams are large structures built across a river to control the river’s flow.Reservoirs are created behind dams.Main GoalsCapture and store runoffRelease water as needed to control floodsMore than 45,000 large dams in world (22,000 of them in China)
16 Building Dams and Reservoirs AdvantagesDisadvantagesProvide irrigation waterProvide drinking waterProvide recreation and fishingCan produce cheap electricity (hydroelectricity)Reduces down-stream flooding of cities and farmsDisplaces people, destroys forests or croplandWater loss to rivers and streamDeprive downstream cropland and estuaries of nutrient-rich siltRisk of failure and devastating downstream floodingDisrupts migration of some fish1 out of five of the world’s freshwater fish and plant species are either extinct or endangered because dams and water withdrawal have sharply reduced the flow of many riversReservoirs behind dams also eventually fill up with sediments such as mud and silt, typically within 50 years, which makes them useless for storing water or producing electricity.
17 Transferring WaterTransportation of water through aqueductsCalifornia Water ProjectTransports water from northern California to southern CaliforniaNorthern CA: Degrades rivers in northern CASouthern CA: More need for waterThink Box: What do you think the effects of this might be on both parts of California?
18 Transferring Water Advantages Disadvantages Supply water to areas that lack enough usable waterAllow farmers to grow water-intensive crops in area that lack sufficient waterWater wasteDegradation to the sourceSubsidies for the cost of water transfers encourage overuseLettuce grown in southern CA despite the fact that it is water intensive
19 DesalinationRemoving of dissolved salts from ocean water or from brackish (slightly salty) water in aquifers or lakes.Two widely used methods:Distillation: involves heating saltwater until it evaporates leaving behind salts in solid form and then condenses as freshwaterReverse osmosis: uses high pressure to force saltwater through a membrane filter with pores small enough to remove the salt14,450 desalination plants in more than 125 countries (250 in the U.S.)Meet less than 0.3% of the world’s demand and 0.4% of the U.S. demand for freshwater.
20 Desalination Advantages Disadvantages More access to freshwater High costEnergy intensivePumping system kills many marine organismsProduces huge quantities of salty wastewater that must go somewhere