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