Groundwater Hydrology

Where does the water come from to start?

•Water Cycle replenishes the groundwater•Infiltration is the movement of water into the

ground•Infiltration occurs due to gravity

•Infiltration continues until the water table is reached- water is then referred to as

groundwater

Zones of underground water

Underground Formations

•All space underground is either an aquifer or a confining bed

•Aquifer: Saturated area that will yield a usable quantity of water to a well

•Confining Bed: Area that will not yield water (impermeable)

Aquifer Conditions

•Confined Aquifer: Has a confining bed (aquitard) overtop- Not open to allow for easy infiltration

-Usually found at great depth-Recharged through cracks in the rock

-Can form artesian wells: wells that force the water to the surface naturally

•Unconfined Aquifer: No confining bed above. Open to easy infiltration of water.

-usually shallow-Water table aquifers

Groundwater Recharge

•Replenishment of the groundwater•Recharge area will transmit water downward unless

blocked by underlying strata-solid rock

-development•“High Recharge Areas”: transmit the most

precipitation and are often referred to as critical recharge areas. Usually higher elevation (hills,

plateaus)

Groundwater Recharge

Discharge Areas

•Areas where groundwater leaves an aquifer (Usually low lying areas)

•Occurs where the water table meets the land surface

-springs and seeps•May flow into surface water features such as

streams, rivers and lakes.

Groundwater Movement

•Groundwater is moved by the force of gravity

•Groundwater can move upwards under the right conditions- high pressure deep aquifers•Upper surface indicates the direction of flow

into an aquifer; Ex. Downslope•AKA “Hydraulic Gradient”

Groundwater movement (cont’d)

•The speed at which water moves through the ground depends on three factors:

1. Permeability of the ground2. Porosity of the rock

3. Hydraulic Gradient (Slope)

Water Supply Wells•When water is withdrawn from a well it will be

replenished from the surrounding aquifer.•Movement of water from the aquifer to the well

creates a change in the surface of the aquifer.•“Cone of Depression”

-funnel-shaped drop in the surface of the aquifer due to the withdrawal of water. The outer limits

of the cone define the area of influence of the well.

Cone of Depression

Fracking Videos

Fracking Explained

http://www.youtube.com/watch?+Uti2niW2BRA

Fracking Animationhttp://www.youtube.com/watch?v=P-EjZ5O-Q18

More Fracking

http://www.youtube.com/watch?v=dEB_Wwe=uBM