1
Hydrologic Cycle is the never ending cyclic exchange of water
between the atmosphere, hydrosphere, lithosphere & biosphere.
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.
Evaporation: occurs as liquid water gains energy from the sun
and changes states into a gas.
2. (Evapo)Transpiration: is the process in
which plants release water vapor into the air.
3. Condensation & Precipitation
occurs when water vapor cools,
energy is lost & changes states
back into a liquid.
B. Subsurface Zones of Ground Water
1. Zone of Aeration is located just below the surface where the
spaces between the soil particles are filled with air.
2. Zone of Saturation is
where the spaces
between the soil
particles are filled with
water.
3. The Water Table is the
interface between the
two zones.
4. Capillary Fringe
occurs where water
is drawn up against
gravity into the zone
of aeration
5. Impermeable rock is the solid bedrock that does not allow
water to pass through it.
6.
Regolith is loose soil or gravel that is not solid rock yet.
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
D. Movement of Water in the lithosphere

1.
Water can run-off the ground or infiltrate into the soil & bedrock.
Run-off; is water that does not sink into
the land but flows along the surface.
2. Infiltration; the process in which water sinks into the ground.
E. Runoff occurs when the soil does not allow rain to infiltrate the ground.
Factors 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.
F. The rate of Infiltration into
the ground is controlled by…
1.
Porosity
2. Permeability
3. Gravity
Porosity is the percentage of open
pore space in a sample of soil.
100 cm3 sample of soil
can hold 45 cm3 of
Water.
Porosity =
Infiltrated
Groundwater
Factors affecting Porosity
1. Particle shape:
Rounded particles have more porosity than angular shaped particles.
2. Packing:
Loosely packed particles have more porosity than closely packed particles.
3. Particle size:
Rounded particles of different
sizes have the same porosity .
4. Sorting:
Porosity of mixed (unsorted)
sediment size particles will be
Low. Porosity of well (sorted)
size particles will be high.
Permeability is the rate at which water will infiltrate (pass through)
soil or bedrock.
Factors 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 settings.
•Infiltration decreased by cement .
•Run-off increases
Ground 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