I Wells are drilled into the zone of saturation to provide water.
I Overpumping of shallow wells produces cones of depression.
I Artesian wells tap confined aquifers in which water is under pressure.
I When groundwater withdrawal exceeds recharge, it lowers the water table
I The most common sources of groundwater pollution include sewage, landfills, and other waste disposal sites.
Understand Main Ideas
1. 1 man4TflEB Evaluate the problems associated with overpumping wells.
2. Explain why artesian wells contain water under pressure.
3. Illustrate the difference between an artesian well and an ordinary well.
4. Differentiate between the effects of radon and the effects of salt dissolved in groundwater.
5. Formulate an experiment which would test if there were impermeable barriers around a polluted area.
6. Analyze how best to prevent groundwater pollution in a residential area.
7. Predict how the permeability of an aquifer can affect the spread of pollutants.
268 Chapter 10 • Groundwater
Self-Check Quiz glencoe.com
268 Chapter 10 • Groundwater
Watcher of the Water
Safe drinking water is something that many people take for granted. Most of the water that is used for human consumption comes from groundwater. Who ensures that ground-water sources remain safe?
Hydrogeologists A groundwater scientist, called a hydrogeologist, is responsible for finding and monitoring groundwater sources to ensure the water supply is free of contaminants and is not used faster than it is replaced. What does a typical day in the life of a hydro-geologist look like? One day might be spent in the field conducting tests on the water levels. The next day might be spent evaluating the data in the office. The day after that might involve looking for trouble in the water-supply line of a house.
Aquifer case study Suppose a farmer wants to install an irrigation system, which involves digging a new well. First, the water level in the area's aquifer must be checked to ensure that a new well will not cause shortages for other users. The hydrogeologist finds an active well nearby and hooks it up to a pump that continuously draws water for 24 hours. Periodic checks of other wells in the area determine the changes in the water level and quality. From the data gathered, he or she computes how much water the aquifer contains and determines the amount of water available for a new well.
Quality assurance Hydrogeologists are also responsible for checking water quality. If the water from a particular aquifer develops a strange taste and odor, the residents would want to ensure the water is safe to drink. The hydrogeologist gathers samples and sends them to a lab to test for various contaminants, such as sewage, pesticides, dissolved metals, or organic material. If a contaminant is found, the hydrogeologist will advise the residents not to drink the water until the source is discovered and the problem is resolved. The hydrogeologist will then begin investigating the problem and searching for clues to find and stop the contamination.
Suppose that, after the farm starts using the irrigation system, a house down the road loses its water supply. The hydrogeologist goes to the house and checks for technical problems, such as a hole in the well casing. If the cause is not technical, he or she will reassess the irrigation system by rechecking the water supply in the aquifer.
Journal Research more about what a hydrogeologist does at glencoe.com. Then, imagine you are accompanying a groundwater scientist on a day on the job. Describe what you saw, what you did, and what you learned about aquifers.
Earth Science and the Environment 269
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Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.