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The Water Cycle. Water vapor was “out gassed” during Earth’s cooling process some 4.5 billion years ago. This volume of water has been recycled ever since. What happens to precipitation that reaches the Earth’s surface?. Water retention. Infiltration. - PowerPoint PPT Presentation
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The Water Cycle
Water vapor was “out gassed” during Earth’s cooling process some
4.5 billion years ago.
This volume of water has been recycled ever since.
What happens to precipitation that reaches the Earth’s surface?
Water retention Infiltration
EvapotranspirationRunoff
Water is trapped on the Earth’s surface as
snow or ice.
Water “seeps” or infiltrates into the
soil.
Water moves across the
surface of the Earth to a large body of water.
Water is evaporated
and/or transpired back into
the atmosphere
What factors can affect the infiltration of water into the soil?
Slope of the land
The steeper the slope, the less likely water
will infiltrate into the ground.
Slop
e of
the
Land
Rate of Infiltration
What factors can affect infiltration?
Vegetation and Land Use
Infiltration tends to be higher in areas where vegetation covers the
soil (ie: grasses, shrubs, trees).
Amou
nt o
f la
nd u
sed
by
peop
le
Rate of Infiltration
Infiltration tends to be poor in areas where the land has been used by
people (ie: compacted soil of farms and/or city landscapes covered by
asphalt).
Rate of Infiltration
Amou
nt o
f ve
geta
tion
Soil SaturationZone of aeration: Area of the soil in which space between soil particles is partially filled with air
and partially filled with water.
Zone of saturation: Area of the soil in which all of space
between soil particles is filled with water (GROUNDWATER).
Water Table: The interface between the zones of
aeration and saturation.
Soil SaturationAs the ground becomes
saturated with water, the water table rises. As the
water table rises, the chance of water infiltrating
the soil will decrease.
Rate of Infiltration
Soil
Satu
ratio
n
Porosity Porosity: The amount of “open space” (pore space) between soil particles compared to the total
volume of soil.
If the amount of “pore space” between soil particles is high, then water will infiltrate the soil more
easily.
Poro
sity
Rate of Infiltration
pore space
Some soil types have a high porosity
due to the size and shape of
the soil particles.
Factors that affect Porosity ShapeRound soil fragments have
a higher porosity than angular soil fragments.
Round fragments
High Porosity
Angular fragments
Low Porosity
Factors that affect Porosity Sorting
Soil fragments that are roughly the same size and shape (sorted) will have a higher porosity than those that are not the same size
and shape (unsorted).SortedHigh
Porosity
UnsortedLow
Porosity
Factors that affect Porosity Packing
Soil fragments that are loosely packed will have a lot of pore
space and will have a high porosity.
Soil fragments that are compacted will have a small amount of pore
space and will have a low porosity.
Loose soilHigh
Porosity
Packed soilLow
Porosity
Permeability Permeability: The ability of a material to allow a fluid to
pass through it.
Different soils have different levels of permeability – or
the rate at which water can move through the soil.
Which soil type do you think has the highest permeability? Sandy soil has the highest permeability.
Capillarity Capillarity: The upward migration of water in soil against the force of
gravity.
Capillarity is commonly found in soils with loosely packed, small particle
size.
The larger the particle size of the soil; the lower the rate of capillarity.
Particle Size
Capi
llarit
y
Which soil sample below has the smallest particle size?
The clay soil sample has the smallest particle size. The
clay shows the best evidence of capillarity as seen by the
highest upward rise of water in the sample.
What factors can affect the runoff of water on Earth’s surface?
Rate of Precipitation Soil Saturation
Slope of the land Rate of Evapotranspiration
If the rate of precipitation is higher than the rate of infiltration, runoff will occur.
If the slope of the land is steep, runoff will occur.
If the rate of evapotranspiration is low, runoff will occur.
If the soil is saturated with water, runoff will occur.
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