Earth’s Water

Aim: What happens to water once it hits the ground?

I. Water Cycle

A.Three phases:

1. Evapotranspiration2. Condensation3. precipitation

II. What can happen to precipitation?

A. It can runoff from the surface into streams, lakes, and the ocean

B. It can be stored in the form of ice and snow on the earth’s surface

C. It can be evapotranspired back into the atmosphere from large bodies of water, soil, plants and animals

D. It can infiltrate (sink into) the ground and become ground water

III. Ground Water Porosity

A. Porosity – the percentage of open space between the particles.B. Porosity is dependent upon:

1. Shape – the rounder the particle the greater the porosity

porosity

rounded

angular

Particle Shape Comparison

2. How tightly packed the particles are. The looser the packing, the higher the porosity.

porosity

loose close

Particle Packing Comparison

3. How well sorted (the same shape and size) the material is. The more sorted the material is, the higher the porosity is.

porosity

unsortedsorted

Particle Sorting Comparison

IV. InfiltrationA. Before runoff and evapotranspiration, water will infiltrate the earth’s surface and become part of the groundwater.1. In order for water to move in through the surface, the surface must be permeable (the ability to pass through) and unsaturated.

permeability

Increasing particle size

Permeability Particle Size Comparison

Bedrock (impermeable)

Zone of SaturationWater table

Zone of Aeration

Soil Profile for Infiltration

•Zone of aeration – portion of ground through which water passes until the water reaches the zone of saturation•Zone of saturation – portion of the ground filled with water and has an upper boundary called the water table.•Water table –the top of the zone of saturation.•Bedrock –solid rock underneath soil or exposed rock at earth’s surface.

2. The depth of the water table is dependent upon:

a. The type of earth materials

b. Thickness of those materials

c. The amount of water infiltrating the ground

d. The characteristics of the surrounding materials (porosity).