Hydrologic Cycle Hydrologic Cycle is the never ending cyclic exchange of water

between the atmosphere, hydrosphere, lithosphere & biosphere.

1

Earth’s Water Supply

 HYDROSPHERE

97.2% Salt Water

2.8% Fresh Water

a. 2.2% Ice and Glaciers

b. .6% Groundwater

c. .01% Streams & Lakes

d. .001% Atmosphere

A. How does water travel from one sphere to the next?

1.1. Evaporation:Evaporation: occurs as liquid water gains energy from the sun and changes states into a gas.

2. 2. (Evapo)Transpiration:(Evapo)Transpiration: is the process in which plants release water vapor into the air.

3. Condensation & 3. Condensation & PrecipitationPrecipitation occurs when water vapor cools, energy is lost & changes states back into a liquid.

B. Subsurface Zones of Ground Water

1. 1. Zone of AerationZone of Aeration is located just below the surface where the

spaces between the soil particles are filled with air.

2.2. Zone of SaturationZone of Saturation is where the spaces between the soil particles are filled with water.

33. The Water TableWater Table is the interface between the two zones.

5. 5. ImpermeableImpermeable rock is the solid bedrock that does not allow water to pass through it.

66. RegolithRegolith is loose soil or gravel that is not solid rock yet.

4. Capillary Fringe4. Capillary Fringe occurs where water is drawn up against gravity into the zone of aeration

C. Capillary Action or (Capillarity):C. Capillary Action or (Capillarity): is the process by which water is drawn up into pore spaces due to the attractive force between water molecules and surrounding materials.  1. PARTICLE SIZE effects the percentage of capillary action.

•Smaller particles will have greater capillarity

2. 2. InfiltrationInfiltration; the process in which water sinks into the ground.

D.D. Movement of Water in the lithosphereMovement of Water in the lithosphere

Water can run-off the ground or infiltrate into the soil & bedrock.

1.1. Run-offRun-off; is water that does not sink into

the land but flows along the surface.

E. Runoff occurs when the soil does not allow rain to infiltrate the ground.

Factors controlling the rate of Run-offFactors controlling the rate of Run-off

1. Impermeable Soil or Bedrock.

2. Soil is already saturated w/water.

3. Rainfall or spring melt exceeds rate of infiltration.

4. Slope is too steep or lacks vegetation.

 

Infiltrated Groundwater

F. The rate of Infiltration intoF. The rate of Infiltration into

the ground is controlled by…the ground is controlled by…

1. Porosity

2. Permeability

3. Gravity

PorosityPorosity is the percentage of open pore space in a sample of soil.

 

100 cm3 sample of soil

can hold 45 cm3 of

Water.

Porosity =

Factors affecting PorosityFactors affecting Porosity

1. Particle shape:1. Particle shape:

Rounded particles have more porosity than angular shaped particles.

2. Packing:2. Packing:

Loosely packed particles have more porosity than closely packed particles.

4. 4. Sorting:Sorting:

Porosity of mixed (unsorted)

sediment size particles will be

Low. Porosity of well (sorted)

size particles will be high.

3.3. Particle size: Particle size:

Rounded particles of different

sizes have the same porosity .

PermeabilityPermeability is the rate at which water will infiltrate (pass through)

soil or bedrock. Factors Affecting PermeabilityFactors Affecting Permeability 

1. Pore size (spaces between soil particles), as pore size increases the permeability of the soil will increase.

2. Interconnections (cracks), as number and size of soil passages increases the permeability increase.

 

3. Impermeable rock will not allow water to infiltrate into the ground

Permeability and Porosity is reduced in urban settingsPermeability and Porosity is reduced in urban settings.

•Infiltration decreased by cement .

•Run-off increases

Ground Water Storage and RechargeGround Water Storage and Recharge

Aquifer: A bedrock unit in which water is stored.

Groundwater Recharge occurs when precipitation is greater then evaporation & can result in a surplus.

     Groundwater Usage can result in the over consumption of water.

During Usage if evaporation is greater then precipitation a deficit

will occur causing a drought.

Ground Water Flow and Wells

Ground Water Pollution & Clean Up