1. Water Beneath the Surface
Groundwater
Water Beneath the Surface

2. What is Groundwater?
Groundwater is the water that is beneath Earth’s surface.
It is a major source of fresh water in the United States.

3. What is an Aquifer?
Aquifer – a body of rock or sediment that stores groundwater and allows the flow of groundwater
In order for water to flow freely, pores or fractures must be present and connected to each other

4. Factors that Affect an Aquifer
The ease with which water flows through an aquifer is affected by porosity and permeability.
porosity: the percentage of the total volume of a rock or sediment that consists of open spaces.
permeability: the ability of a rock or sediment to let fluids pass through its open spaces, or pores

5. Factors that Affect Porosity
Sorting – the amount of uniformity in the size of the rock or sediment particles.
well sorted = sediment are all about the same size
poorly sorted = sediment contains particles of many sizes
loosely packed particles = many open spaces that can store water, so the rock has high porosity
tightly packed particles = few open spaces, so has low porosity

6. Sorting – draw this sketch in notes
well sorted well sorted poorly sorted

7. Factors that Affect Permeability
To be permeable, open spaces must be connected
The larger and better sorted the particles are, the more permeable the rock or sediment tends to be

8. Are All Soils Permeable?
Water flows well through gravel and sand
Water will NOT flow through clay, which is impermeable

9. Groundwater Zones
Water is pulled down through soil and rock layers by gravity until it reaches an impermeable layer. The water then begins to fill or saturate, the spaces in the rock above the impermeable layer. As more water soaks into the ground, the water level rises underground and forms two distinct zones.
1. zone of saturation
2. zone of aeration

10. Groundwater Zones

11. What is the Zone of Saturation?
The Zone of Saturation is the layer of an aquifer in which the pore spaces are completely filled with water.
It is the lower of the two zones of groundwater
The upper surface of this layer is called the water table.

12. What is the Zone of Aeration?
The Zone of Aeration is the zone that lies between the water table and the Earth’s surface
It is composed of three regions:
The uppermost region holds soil moisture
The middle layer is dry, except during periods of rain, and thus contains air in its pores
The bottom region is the capillary fringe (causes water to be drawn/soaked up from the zone of saturation)

13. Groundwater Zones

14. How does Groundwater Flow?
Downward
Flows downward in response to gravity
This rate is dependent on the rock layers (permeability)
Horizontally
This rate depends on the permeability of the aquifer and the gradient, or steepness, of the water table

15. How Deep is the Water Table?
The depth of the water table depends on:
Surface topography
The permeability of the aquifer
The amount of rainfall
The rate at which humans use the water

16. How Deep is the Water Table?
During periods of prolonged rainfall, the water table rises
During periods of drought, the water table falls and flattens

17. Why Should We Conserve Groundwater?
In some areas, groundwater is the only source of freshwater
Replacement of this water can take hundreds or thousands of years to replenish

18. What is a Recharge Zone?
A recharge zone is anywhere that water from the surface can travel through permeable rock to reach an aquifer

19. What is a Recharge Zone?
Pollution in a recharge zone needs to be avoided or it can contaminate the groundwater supply

20. How Does Groundwater Reach the Surface?
A well is a hole that is dug to below the level of the water table
A spring is a natural flow of groundwater to Earth’s surface in places where the ground surface dips below the water table

21. What is a Hot Spring?
Groundwater is heated when it passes through rock that has been heated by magma
Groundwater that is at least 37ºC (98ºF) and rises to the surface before cooling produces a hot spring
Hot springs that periodically erupt form surface pools or through small vents are called geysers

22. What is a Hot Spring?

23. Create flashcards for the following:
ASSIGNMENT:
Create flashcards for the following:
Groundwater
Permeability
Porosity
Infiltration
Aquifer
Water table
Recharge zone