SCIENCE 8Unit 1- Water Systems on Earth

Slideshow 1Chapter 1 -The water cycle plays a

vital role on EarthSection 1.3 – Sources of Fresh Water

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1.3 Sources of Fresh Water

• Lakes, ponds and wetlands

• Streams and rivers

• Ground water• Glaciers• Drainage basins

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Ground Water

• Ground water is water that soaks into the ground Rock/ground with good porosity allows more water to enter More pores (spaces in the rock/soil), the better the porosity An aquifer is a layer of porous rock that allows ground

water to flow, almost like a river below the surface.

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Ground Water

•Humans get fresh water from Reservoirs, natural or man-made Wells, drilled into aquifers down to the water table

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Run-Off

• Precipitation becomes run-off as gravity pulls water down into the groundwater, a lake or an ocean basin.

Q…Suggest some conditions which might increase run-off.

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Run-Off

• Factors That Affect RunOff Type of Surface - Soil vs Rock Saturation of Ground – Saturated soil means more runoff Slope - The Steeper the slope the more run off Vegetation – Less Vegetation more runoff Human Development – ie more runoff on concrete or

pavement.

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Drainage Basins

• Drainage basins are large areas where surface water all moves towards one main river Run-off flows into streams and

smaller rivers, which are tributaries of large rivers, forming a branching system

See e 379

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Drainage BasinsDrainage Basins

•Watershed• The area of land that drains into a body of water such as a river, pond, lake or ocean.• There may be many small watersheds within a larger drainage basin.

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6 Major Drainage Basins in NL6 Major Drainage Basins in NL

1. Labrador Sea 2. Gulf of St. Lawrence3. West Coast Gulf of St. Lawrence4. South Coast Gulf of St. Lawrence5. Atlantic Ocean Avalon Peninsula6. Atlantic Ocean North-east Coast

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Glaciers

• Almost 66% of all fresh water on Earth is in glaciers

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Alpine Glaciers (right) Found in

mountain valleys Continental Glaciers of Antarctica

(above)

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• Glaciers slow down the passage of water through the water cycle by storing vast quantities of water. They release the water during the hot summer months.

GlaciersGlaciers

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Water trapped in glacial ice

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The Ice AgeThe Ice Age

• The most recent began 120 000 years ago ending 11 000 years ago.•Glaciers covered ~ 20% of land on Earth.

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The Ice AgeThe Ice Age

Why Do you think the coastline during the ice age differed from the modern coastline???

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Glaciers and Global WarmingGlaciers and Global Warming

• In the last 100 years the average temperature has increased dramatically.• The world’s glaciers are melting at a quicker paces than ever before.

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Melting Greenland Glacier

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Receding Athabasca Glacier in AlbertaIt has

receded 1.5 km since

1843.

Glaciers and Global WarmingGlaciers and Global Warming

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Glaciers and Global Warming

Q….Suggest Some implications of the glacier melting.

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What does this mean?What does this mean?

• Sea Level may rise• Salinity of Oceans may decrease• Flood rivers• If glaciers disappear, rivers may dry up