Groundwater chapter 10

DEFINE EACH TERM – on separate sheet

Infiltration
Pores
Porosity
Permeable
Impermeable / Water table
Aquifer
Aquiclude
Zone of aeration
Zone of saturation / Spring
Sink hole
Karst topography
Stalactite
Stalagmite / Geyser
Artesian well
Drawdown
Cave / Subsidence
Contamination
Septic tank
Pesticides

The vast majority of Earth’s water is un-drinkable salt water in the oceans. The rest is freshwater but most of that freshwater is frozen and unusable. From the graph below you can see that of all the water on Earth, only 3% is freshwater while the other 97% is salt ocean water. The middle circle graph shows how almost 70% of all the freshwater is frozen water. The rest of the freshwater is almost all groundwater while only a very small portion of freshwater is from surface water (lakes, rivers etc). Of all the usable resources of freshwater, groundwater is the most abundant. About 50% of America’s population rely on groundwater for their freshwater source.

/ Here is a rough diagram of the different layers involved with groundwater. First the water infiltrates the ground. It then passes through a porous top layer called the zone of aeration, on its way to the aquifer. The water is stopped at the bottom by the aquiclude. The bottom layer is the aquifer and has large pores where water can flow. The area that is filled with water is the zone of saturation. The top of the zone of saturation is the water table.

Caves - Caves can be enormous underground structures and they are made from the weathering and erosion due to groundwater. When water infiltrates the ground it picks up carbon dioxide from the soil. This makes the water acidic and the water develops a small concentration of carbonic acid. This acidic groundwater dissolves the limestone under the ground. As this limestone dissolves and is washed away by flowing groundwater in the aquifer, a cave is formed. Dripping groundwater from the ceiling of the cave will leave behind mineral deposits. These are small grains of minerals that will collect as a solid. Much like if you let salt water evaporate and the salt stays behind while the water disappears. These mineral deposits will shape a formation from the ceiling (stalactite) like an icicle hanging from your gutters in the winter. The same formation can be formed on the floor of the cave from the same dripping water (stalagmite).

Geysers / Springs /Wells - A spring is a natural opening where groundwater can release to the surface. There are times when the groundwater is heated by magma underground and becomes a hot spring. Other times, the heated water creates steam and that steam then develops pressure. When the pressure build high enough the water erupts and the shoots into the air. This is called a geyser.

In order to reach groundwater, a well will be dug into the ground and so that the water can be pumped up to the surface. If the well isn’t dug deep enough, it will limit the amount of water that can be drawn out of the aquifer. About 50% of the American population relies on groundwater for its freshwater. There is also a special type of well where the water is pressurized. The groundwater is trapped between two aquicludes. When a well is dug through the upper aquiclude it’s like poking a hole into a hose. The pressurized water will shoot up out of the well and not need to be pumped out.

Groundwater – layers and vocabulary terms

/ Here is a diagram of rain travelling through the ground and becoming groundwater. There is also a list below of definitions of each important term

Infiltration - the process of water soaking into the ground

Pore – open spaces in a material or in the ground. This is where water can enter and flow

Permeable – the ability for a material to allow water to enter and flow

Water table – the top surface of groundwater

Aquifer – the area under the ground that is able to hold groundwater. It is the ‘container’ of groundwater

Aquiclude – an impermeable layer that prevents water from passing through

Zone Aeration – the area near the surface where water passes through on its way to the aquifer

Zone of saturation – the are where the groundwater occupies. (Example – If you have a glass of water. The glass would represent the aquifer and the amount of the glass that is filled with water is the zone of saturation

Groundwater Diagram

Label the parts of the groundwater diagram. Place your answers next to the numbers below the picture

1.
2. / 3.
4. / 5.
6.

Now write a short definition for each term.

1.
2.
3. / 4.
5.
6.

Wells

Ordinary Well

Wells are drilled or dug into the ground to reach the aquifer and used to draw out groundwater. There are ordinary wells and artesian wells. An ordinary reaches the aquifer and draws out its groundwater. The groundwater then replenishes itself. Water is sometimes drawn out of a well faster than the groundwater can replenish (recharge). The difference between where the water table was and the level of the overdrawn well is called the drawdown. Overdrawing from a well and the drawdown of the water table can lead to salt water contamination if the well is near the ocean. We will speak more about this later. It is simple to understand that the deeper the well, the more water the well will have access to.

Ordinary Well – here are two ordinary wells. The well that has the best access to the most groundwater is the one that is dug deeper. Well “B” / Drawdown – Here we see that well B has been over pumped and there is a depression at the well. This is an example of ‘drawdown’
/ Artesian Wells
In the diagram to the left you see an area of land with two aquicludes. Having two aqucludes requires water to enter the aquifer through a specific place called the recharge area. In this case it is located at the top of a hill and water enters the aquifer like lowing water at the end of a water hose. since the recharge area is elevated, the water in the aquifer below is pressurized. The pressured water will push its way up to the level of the water table and be forced out of the well. This is an example of an artesian well.
  1. Explain why the zone of saturation is different from the aquifer?
  1. Define the term ‘recharge’
  1. What is the difference between ordinary and artesian wells?
  1. Why does water flow out of an artesian well?
  1. What is drawdown?

Surface water unit – chapter 9

Define each term – on separate sheet

Water cycle
Runoff
Watershed
Divide / Suspension
Bed load
Discharge
Flood / Rejuvenation
Floodplain
Stream channel
Stream bank / Base level
Meander
Delta
Eutrophication
Wetland

Think About It Questions

  1. The term “downcutting” is used in the text. What do you think this term might mean?
  1. Look up the geek letter “delta”. Why do you think the term delta is used to name this deposit of silt and other materials?
  1. The Appalachian Mountains are found on the East part of the country. Predict where run-off will flow as rain falls on the West side of the mountain range and on the East side.
  1. The text uses the term “rejuvenated”. Define this word and use it in a sentence that is not related to the topic of surface water.

Surface Water


Across

2. the land on the sides of a stream

3. the flow of precipitation to a body of water

7. triangular shaped deposit of silt at the mouth of a river

11. to bring back to life

12. a place where two divides are separated

Down

1. process where H2O is circulated around the world

2. a long narrow depression in the earth where water flows freely

4. low lying ground near a river that can often flood

5. lowest point of a river or stream

6. area of land where water runs off

8. part of a stream that winds back and forth

9. when material doesn't sink or float and remains in between

10. particles that move in a stream by rolling or sliding at the bottom of the stream