Factors That
Affect Infiltration
And Runoff
1. Slope of the Land
The steeper the slope, the less infiltration. More
runoff occurs.
As slope increases, infiltration decreases
Infiltration
Indirect
Relationship
Gradient
SOIL CHARACTERISTICS
This is water
that is NOT
infiltrating the
soil. Instead it
is forming
runoff.
A. Porosity
• Definition - percent of ___________
open spaces in
soil
a. Porosity
• Particle size alone does not determine
porosity
• Identically shaped samples of increasing
particle size will have the same porosity
Porosity and Shape
• Rounded
Vs.
Angular
Which is more porous?
HIGH
POROSITY
LOW
POROSITY
Porosity and Packing
• Loose
Vs.
Close
Which is more porous?
HIGH
POROSITY
LOW
POROSITY
Porosity and Sorting
• Sorted
Vs.
All the same size
Unsorted
Different sizes
Which is more porous?
HIGH
POROSITY
LOW
POROSITY
Which is more porous, a container of:
a. round particles
or
angular particles
b. tightly packed particles or
loosely packed particles
c. well-sorted particles
or
unsorted particles
d.
or
small beads
large beads
***Particle size alone does not determine porosity***
b. Permeability
The ability to let water pass through it
• Soils made up of large particles are very
permeable and have high infiltration rates
• For soils to be permeable, the ____________
Pore spaces
must be connected
* Clay soils absorb water at a very slow rate, small
particle size, low permeability (clay has the
smallest particle size)
In which soil will water move
through more quickly?
water
water
water
Which column would allow water to flow
through faster and why?
If you join sediment from A and D,
what would happen to the permeability? Why?
Which is more permeable?
a.
small particles or
large particles
b.
frozen ground or
unfrozen ground
c. Capillarity (Capillary Action)
• The ability of water to flow upward through
soil.
– Very important to people who grow crops
• Soils made up of very small particles have
the highest capillarity.
– More surface area for water to cling to
Draw a line to complete the graph below:
Capillarity
high
low
small
Particle size
large
3. Degree of Saturation
• If the ground is already saturated (fully
soaked), then water will more likely
__________
runoff
4. Vegetation vs. Land Use
• Vegetation – little runoff
• Land Use - paved streets, parking lots –
more runoff
Factors Affecting Infiltration:
5.) Ground
Temperature—
frozen ground limits
infiltration of rain
and also causes
runoff of melting
snow
Which will result in greater runoff and stream discharge?
a. an area that is vegetated
or
an area that is barren
b. an area that has a steep slope
or
an area that is flat
c. ground that is frozen
or
ground that is unfrozen
d. ground that is saturated
or
ground that unsaturated
Binghamton flood 2011
• http://www.youtube.com/watch?v=aqrY7P
peV8s&feature=fvwrel