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Water Resources

Water Resources. 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. Importance of Freshwater. Necessary for life 60% of us is composed of water

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Water Resources

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  1. Water Resources 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 life • 60% of us is composed of water • Could only survive a few days without it • Takes huge amounts to supply us with food, energy etc..

  3. Management of Freshwater • Poorly managed • Charged less than its worth How would charging less thanwater’s worth contribute to the mismanagement of water?

  4. Issues with water • Global • Economic • National and global security issue • Environmental

  5. Availability of Freshwater • Only about 0.024% of the planet’s water is available to us as liquid freshwater • Sources: • Groundwater deposits • Lakes • Rivers • Steams

  6. Groundwater • Precipitation 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 top • Zone of saturation: Deep; Completely filled with water • Water zone: top of this groundwater zone • Aquifer: Deep; Groundwater flows through them; pumps used to bring water to surface; replenished mainly by precipitation

  7. Groundwater • Surface 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 ground • Watershed (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 flooding • World-wide averages • Domestic: 10% • Agriculture: 70% • Industrial use: 20%

  9. Water Footprint • Volume of water we directly and indirectly • Average American uses 260 liters per day • Flushing 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 liters • Virtual water often exported/imported • Grains and other foods

  11. Water Shortages • Main factors • Dry climates • Drought • Too many people using a normal supply of water • Wasteful 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 India • 30% earth’s land area experiences severe drought • Will rise to 45% by 2059 from climate change • Potential conflicts/wars over water • Refugees from arid lands • Increased mortality

  13. Think Box • What do you think we can do to increase freshwater supplies?

  14. Extracting Groundwater Advantages Disadvantages Aquifer depletion from overpumping Sinking of land from overpumping Pollution of aquifers lasts decades or centuries Deeper wells are nonrenewable • Useful for drinking and irrigation • Exists almost everywhere • Renewable if not overpumped or contaminated • Cheaper to extract than most surface water

  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 Goals • Capture and store runoff • Release water as needed to control floods

  16. Building Dams and Reservoirs Advantages Disadvantages Displaces people, destroys forests or cropland Water loss to rivers and stream Deprive downstream cropland and estuaries of nutrient-rich silt Risk of failure and devastating downstream flooding Disrupts migration of some fish • Provide irrigation water • Provide drinking water • Provide recreation and fishing • Can produce cheap electricity (hydroelectricity) • Reduces down-stream flooding of cities and farms

  17. Transferring Water • Transportation of water through aqueducts • California Water Project • Transports water from northern California to southern California Think Box: What do you think the effects of this might be on both parts of California?

  18. Transferring Water Advantages Disadvantages Water waste Degradation to the source Subsidies for the cost of water transfers encourage overuse • Supply water to areas that lack enough usable water • Allow farmers to grow water-intensive crops in area that lack sufficient water

  19. Desalination • Removing 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 freshwater • Reverse osmosis: uses high pressure to force saltwater through a membrane filter with pores small enough to remove the salt

  20. Desalination Advantages Disadvantages High cost Energy intensive Pumping system kills many marine organisms Produces huge quantities of salty wastewater that must go somewhere • More access to freshwater

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