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 Water Resources LT 6E: Discuss the sustainability of freshwater resources LT 6F: Identify possible solutions to the sustainability of freshwater resources.

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Presentation on theme: " Water Resources LT 6E: Discuss the sustainability of freshwater resources LT 6F: Identify possible solutions to the sustainability of freshwater resources."— Presentation transcript:

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

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

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  Provide irrigation water  Provide drinking water  Provide recreation and fishing  Can produce cheap electricity (hydroelectricity)  Reduces down-stream flooding of cities and farms 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

17 Transferring Water  Transportation of water through aqueducts  California Water Project  Transports water from northern California to southern California

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

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


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