Post on 18-Dec-2015
transcript
Porosity, Permeability,
Capillarity
Porosity is determined by:
1. Shape - Well rounded particles have greater porosity than angular.
ROUND ANGULAR
Porosity - The amount of space in between sediments.P
OR
OS
ITY
ROUNDNESS
2. PACKING- The more closely packed the particles the lower the porosity.
UNPACKED PACKED
PO
RO
SIT
Y
PACKING
3. SORTING- - If all particles are the same size they are sorted. - If the particles are different sizes they are unsorted (poorly sorted) - The more sorted the higher the porosity
PO
RO
SIT
Y
SORTING
Particle Size alone does NOT affect porosity!!!!!
(Shaping, Packing, Sorting does)
Permeability Ability of water to pass through Affected by: packing and particle size Tighter packing and Smaller particles =
less permeability Looser Packing and
Larger particles = more permeability
PE
RM
EA
BIL
ITY
PARTICLE SIZE
Other things about Permeability
Permeability Rate – How fast a fluid can flow through a material
Impermeability (not permeable) is due to:
A. Tightly packing of particlesB. Cementing of particles by clayC. Cementing of particles by ice
GRAVEL Rapid
drainage
FINE SANDModerate drainage
CLAYSlow
drainage
PERMEABILITY
Clay is impermeable – water will not flow through easily
Capillarity- Water sticks to the materials that it ispassing through.
Capillarity Water - Water stored in the zone of aeration
Capillarity causes water to move upward from the water table (capillary action)
Capillarity increases with a decrease in particle size.
CA
PIL
LA
RIT
Y
PARTICLE SIZE
Capillarity
INFILTRATION
Infiltration refers to water soaking into the ground:
Infiltration rate
Slope
Infiltration rate
Permeability
Infiltration rate
Porosity
Infiltration rate
Soil Storage Saturation