Water Resources

Global Distribution71%of Earth’s surface is water 97% of Earth water is Salt

water

77% of the fresh water is frozen

Surface WaterDrinking waterWater for cropsFood

fish and shellfish

Power for industry

Transportation

Surface WaterRiver 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

Ground Water – water beneath Earth’s SurfaceWater 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.

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.

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.

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