Journal #12
 What is an aquifer?
 Where does water in an aquifer come
from?
Zones of Aquifers
 Gravity pulls water down through soil and rock
layers until the water reaches impermeable rock.
 Water then begins to fill the spaces in the rock
above the impermeable layer.
 As more water soaks into the ground, the water
level rises underground to form 2 zones of
groundwater.
Zone of Saturation
 The layer of an aquifer where the pore space is
completely filled with water is the zone of
saturation.
 The zone of saturation is the lower of the 2 zones
of groundwater.
 The upper surface of the zone of saturation is
called the water table.
Zone of Aeration
 The zone that lies between the water table and
Earth’s surface is called the zone of aeration.
 This zone is composed of three regions:
 Soil moisture region- uppermost region and holds
water in top soil.
 Capillary fringe- the bottom region, just above the
water table,.
 Water is drawn up from the zone of saturation into
the capillary fridge similarly to how a towel draws
up water from a spill
 This action is called capillary action.
Movement of Ground Water
 Like water on Earth’s surface, groundwater flows
downward in response to gravity.
 Water flows quickly through rock that highly
permeable.
 The rate at which groundwater flows depends on
the gradient
 Gradient- is the steepness of the slope
 As the gradient (slope) increases, the faster the
water flows.
Topography and the Water Table
 The depth of the water table depends on:
 Topography (arrangement of the land)
 The permeability of the aquifer
 Rate at which humans use the water
 During periods of prolonged rainfall, the water
table rises
 What do you think happens during times of
drought?
Perched Water Table
 Only one water table exits in most areas
 In some areas, a layer of impermeable rock lies
above the main water table.
 This rock prevents water from reaching the main
zone of saturation.
 Water collects on top of this upper layer and
creates a second water table called a perched water
table.
Conserving Groundwater
 In many areas, groundwater is the only source of
fresh water.
 Communities often regulate the use of
groundwater, discourage excess pumping, and
recycle used water.
 Surface water enters an aquifer through an area
called a recharge zone.
 Recharge zones are sensitive to pollution, as it can
contaminate the entire aquifer.
Your Assignment
 Draw a diagram of an aquifer.
 Use lots of color and give it a title (20 points)
 Label: ( 10 points each)
 Aquifer
 Zone of saturation
 Zone of aeration
 Water table
 Soil moisture region
 Capillary fringe
 Recharge zone
 Perched water table