Water Resources

1. Water Resources

3. Global Distribution 71%of Earth’s surface is water 97% of Earth water is Salt water 77% of the fresh water is frozen

4. Surface Water • Drinking water • Water for crops • Food • fish and shellfish • Power for industry • Transportation

5. Surface Water • River system – streams form from falling rain, melting snow drains. As streams flow downhill they combine with other streams to form rivers. • The more streams that flow into the river the larger the river. • Watershed – the area of land that is drained by a river

6. Ground Water – water beneath Earth’s Surface • Water table - level where rocks and soil are saturated with water. Level depends on the amount of rainfall or proximity to a large body of water.

7. Aquifers • an underground formation that contains groundwater. • Water table is the upper boundary. • A Water table is a large space where water can pool, like caves or underground lakes.

8. Rocks contain small holes or pore spaces • Porosity – the percentage of total volume of a rock that has spaces (pores). The more porous a rock is the more water it will hold • Permeability – ability of the rock to let water flow through it. • Gravel is very permeable, but clay and granite do not let water flow through so they are impermeable. • Most productive aquifers usually form in permeable materials – sandstone, limestone, or layers of sand and gravel.

9. Recharge Zone – area of earth’s surface from which water percolates down into an aquifer. • Size depends on permeability of surface above the aquifer. Buildings, parking lots, etc. are impermeable layers so communities have to take this into account when allowing building. • Can take tens of thousands of years to recharge