1. CON 101 Waters Frank Smith ><<{{{(‘>
Groundwater
CON 101 Waters
Frank Smith
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2. Groundwater
All the water contained in the pore spaces of rock and soil below the elevation of the water table

3. Who Uses Groundwater?
More than 50% of the people in the U.S. use groundwater for drinking and other uses
75% of cities and industries use groundwater for some purposes
the largest use of groundwater is for irrigation of crops

4. Groundwater
Water table: the upper limit of groundwater

6. AQUIFER
An aquifer is a wet underground layer of water -bearing permeable rock or unconsolidated materials (gravel, sand, or silt) from which groundwater can be usefully extracted using a water well.

7. Unconfined aquifers: In unconfined aquifers, water has simply infiltrated from the surface and saturated the subsurface material. If people drill a well into an unconfined aquifer, they have to install a pump to push water to the surface.
Confined aquifers: Confined aquifers have layers of rock above and below it that are not very permeable to water. Natural pressure in the aquifer can exist; pressure which can sometimes be enough to push water in a well above the land surface. No, not all confined aquifers produce artesian water, but, as this picture of an artesian well in Georgia, USA shows, artesian pressure can force water to the surface with great pressure.

8. What is an aquifer?
Underground soil or rock through which groundwater can easily move
Movement depends on the size of the spaces and how well connected
# of spaces = porosity
Degree of connectivity is “permeability”

9. Permeability # of spaces = porosity
Degree of connectivity (rate) is “permeability”

11. SINKHOLES and the AQUIFER Sinkholes originate beneath the surface when groundwater moves through the limestone and erodes large voids, or cavities, in the bedrock. When water fills a cavity, it supports the walls and ceiling, but if the water-table drops, the limestone cavity is exposed to further erosional processes that eventually result in the collapse of the cavity, causing a surface indenture, or sinkhole. The sinkhole becomes a primary site of recharge, where surface water can enter the aquifer and replenish the groundwater supply.

12. Groundwater discharge
Groundwater discharge is the volumetric flow rate of groundwater through an aquifer.

13. Rate Of Discharge

14. Groundwater recharge
Groundwater is recharged naturally by rain and snow melt and to a smaller extent by surface water (rivers and lakes). Recharge may be impeded somewhat by human activities including paving, development, or logging. These activities can result in enhanced surface runoff and reduction in recharge. Use of groundwaters, especially for irrigation, may also lower the water tables.
Aquifer

15. How do we get water from an aquifer?

16. Cone of depression

18. Perched Water Table - Springs
Any natural situation where water flows to the surface of the earth from underground. Thus, a spring is a site where the aquifer surface meets the ground surface.

19. Artesian Aquifer

20. Ground Water Contamination

21. What haven’t we discussed?

22. Water Balance Equation
P = Q + E + ΔS
P = Precipitation Q = Runoff E =Evapotranspiration
ΔS =change in storage (in soil or the bedrock)

23. ET--Evapotranspiration
2 parts
Evaporation
From oceans, streams, lakes, soil moisture
Makes up 90% of atmospheric moisture
Transpiration
Movement of water through plant and escaping through stomata of plant leaves.
Makes up 10%atmospheric moisture

24. Examples:
1A corn transpires gallons of water each day.
Oak tree (large) transpires 40,000g/year

25. Factors Affecting Transpiration
Temperature
Relative Humidity
Wind & Air Movement
Soil Moisture Availability
Type of Plant