Porosity and Permeability

Which surface material will allow

water to infiltrate in or run-off?

What determines if precipitation will INFILTRATE the ground or RUN-OFF the surface?

Predict which will allow the water to infiltrate better

soil sand gravel

Permeability• Ability to transmit water through

connected pore spaces

http://www.classzone.com/books/earth_science/terc/content/investigations/es1401/es1401page03.cfm Permeability of shale, sandstone and limestone

Amount of pore spaces, openings. Ground materials ability to store and HOLD water.The percent % of the total volume of material that consists of pore spaces

Porosity & Permeability Lab

Predict which material will have the greatest permeability to water.

Which material transmitted the most water through in the LEAST AMOUNT OF TIME?

Which material transmitted the MOST water through it?

Results: Permeability

Large grained, passes through easily. __________

Fine grained, passes through slowly. ___________

Very fine grained, cannot pass through at all.

____________

Highly porous but doesn’t pass through__________

material

gravel, coarse sand

Fine sand

Clay, shale

Pumice rock

The pore spaces aren’t connected!

(impermeable)

Porosity factors: 3-S’s• Size of particles: (large, small, fine)

• Shape of particles (rounded or angular)

• Sorting of particles: - well-sorted: all the SAME size and shape

- unsorted: mixed, DIFFERENT size and shape• Compactness of particles

Which is well-sorted? Compacted? Un-sorted?

saRank the following as #1 for the highest porosity and #5 as the lowest porosity.

And describe factors

Good porosity

Due to:

Round shape

Same size

well-sorted

LOW porosityDue to:unsortedSmall clay particles fill-in the pore spaces between the large particles.

High porosity

Due to:

Same big size

Same shape

Well-sorted

High porosity

Due to: Big sizeBut.. unsorted and angular

Good porosity.

Due to:

Same size

Well-sorted

sand Clay soil

Post-lab graphs

Unsorted well-sorted

poro

sity

1. Sketch a graph that shows the relationship between porosity and particle size

2. Sketch a graph showing the relationship between porosity and sorted

Particle size

3. Sketch a graph showing the relationship between porosity and shape.

(round vs. angular)

Lag Time:

the time between rainfall and when the water reaches the river as

discharge

Permeabilityvs

Streamflow

Factors:

Whether rain will infiltrate the ground or run-off is determined by POROSITY and PERMEABILITY of the ground material.

Permeability and Porosity Activity

• Use the Google Picture of the area. Decide if each square is Permeable or Impermeable and put that color tally mark on the square. Tally the total of each in the chart.

• Use the article to help you answer the questions.

Aquifer – water that infiltrates and is stored underground in the spaces between the rock particles.

Aquifer

Groundwater

U. S. Aquifers

How much space is in sandstone for it to hold water?

Groundwater is the most abundant available source of fresh water

Rivers, lakes, streams = 1.4% of fresh water

Zone of aeration • Unsaturated zone • Pore spaces are filled

mainly with air

Zone of saturation • All pore spaces in the

material are filled with water

• Water within the pores is groundwater

Water table – the top of the zone of saturation

Groundwater ContaminationCaused by:Sewage from septic tanksHighway saltFertilizers, pesticidesIndustrial chemicals that leak from pipes and

storage containersLandfill