GROUNDWATER DEPLETION
BACKGROUND
Groundwater is a vital system of underground reservoirs. These contain the world’s largest supply of usable fresh
water. In some areas that receive low rainfall, the withdrawal of groundwater from aquifers exceeds the rate at which
rainfall can recharge the system.
Only 5% of the water drawn from aquifers is the drinking and domestic uses. Almost 75% is used for irrigation
worldwide the remaining 20% goes to industrial uses. In developing countries, even higher percentages are used to grow
food.
PART A
In the space on the answer sheet, draw a diagram of the world’s water cycle and label each of the following
processes and components. Use arrows to show the flow of fresh water. Then answer the analysis questions on the
following page.
Condensation
Evaporation
Precipitation
Lakes
Oceans
Rivers
Clouds
Sun
Percolation
Infiltration
Watershed Runoff
Groundwater
Surface Water
Aquifers
Plants
Animals
Glaciers/Snow Fields
PART B
Incident Report #1
In California’s San Gabriel Valley, an area 20 kilometers east of Los Angeles, groundwater is being pumped out of the
main San Gabriel Groundwater Basin. In 1989, the situation describing the groundwater contamination in the area was
presented at a congressional hearing. California takes half of its drinking water from groundwater, and agriculture uses
five times that much for irrigation. Because the soil is sandy and porous, harmful pesticides were easily washed into the
groundwater. At the time the pesticide use began, the hazards were not known. Also, California agriculture uses 50% of
the pesticides used in the entire United States each year. The groundwater was also contaminated by industrial
discharges, leaking chemical storage facilities, illegal dumping, and poorly designed landfills.
Incident Report #2
In Dayton, Ohio, a fire broke out in an old paint warehouse in May of 1987. Firefighters battled the fire and quickly
put it out. Unfortunately, the warehouse was built in an industrial park surrounding Dayton’s field of water wells. The
aquifer was only three meters below the ground in some places and the hazardous materials mixed in with the water from
the fire, and the pollutants began to leak into the groundwater. As city officials tried to contain the contamination, the
pollutants began to leak into the groundwater. As city officials tried to contain the contamination, they found out that
abandoned sand and gravel quarries in the area had been used for dumping hazardous materials. These materials were
leaking into the drinking water of nearly 1 million people.
Incident Report #3
In China, 50 cities are threatened by shortages of water because groundwater is extracted faster than the systems
can be recharged. The water table beneath Beijing is sinking by almost 2 meters a year and a third of its wells are
suspected to be dry already. Currently, 41 large cities use groundwater polluted by nitrates from fertilizers from the
extensive farmland regions. China uses more than 80% of its water for agriculture. As a result, China is chronically
short of safe water, and between 1950 and 1980 they built 90,000 small dams to try to trap additional surface water.
Incident Report #4
In southern India, the water table has fallen 25 meters since the early 1980s. This is due primarily to the pumping
of water for agriculture in Tamil Nadu. In the northern part of the country, the number of villages short of water in the
state of Uttar Pradesh has risen from 17,000 to 70,000 in the last 20 years. Of the 2,700 water supply areas provided
by the government, 2,300 have dried up. India uses more than 93% of its water for agriculture to grow food for its
growing population. Desalinization plants are still too expensive to lessen India’s water shortages.
Incident Report #5
The Florida Everglades is an important marsh in southern Florida and is located south of Lake Okeechobee. To
increase farming in the region, canals were cut from the lake to the Gulf of Mexico and to the Atlantic Ocean. This
diverted water from Lake Okeechobee and its drainage basin has stopped the flow of water the The Everglades marsh.
Lake Okeechobee recharges the Biscayne Aquifer which supplies drinking water for 4.5 million residents of Florida. In
addition, much of The Everglades marsh was diked and equipped with huge drainage pumps so that sugar cane could be
grown. Decomposition of the soils has resulted in the release of massive amounts of nutrients and fertilizers into the
system. As a result, Everglades National Park is in danger. With the lowering of the water table, saltwater intrusion is
occurring in coastal regions, killing native cypress trees. Sinkholes have developed where land has subsided.
Incident Report #6
In Reno County, Kansas, the state Department of Health has been investigating the Obee Road site since July 1983.
Organic chemicals had been detected at the site, including benzene, toluene, vinyl chloride, trichloroethylene, and others.
The contaminants had leaded into the shallow aquifer that supplied suburban residents of Reno County. The source of
the contaminants was tentatively identified as the former city of Hutchinson landfill. Until the landfill closed in 1973,
this site had accepted unknown quantities of liquid waste and sludges from local industries, and solvents from the
Department of Defense and local aircraft plants. Individual septic tank systems may also have contributed to the
contamination because they are commonly cleaned using benzene, trichloroethylene, and dichloromethane. The Obee
school system had been drawing its water from a contaminated well, but it is now receiving an alternate water supply.
GROUNDWATER DEPLETION
PART A – Draw the world’s water cycle using the terms on the paper provided.
ANALYSIS
1. The world’s ocean is made up entirely of salt water. What is the role, if any, of the ocean in the world’s fresh water
cycle?
2.
Describe 2 ways in which agricultural irrigation can affect the groundwater system in an area.
3.
Describe 3 ways in which animals contribute to the water cycle. Are animals an essential part of the cycle? Why or
why not?
4.
How might global warming, caused by an increase in heat-trapping gases in the atmosphere, affect the water cycle?
5.
About 113,000 billion cubic meters of precipitation fall to Earth each year. Yet the world only uses about 3,500 cubic
meters of this precipitation. The rest evaporates or flows into the oceans. Why do you think people use so little of
the precious resource?
PART B – Answer the following questions for 3 of the Incident Reports on the Groundwater Depletion Worksheet. Be sure to
include the Incident Report # with your answer.
1.
Where and when did the incident occur?
2.
What caused the problem and what was the effect?
3.
What could be, should be, or was done to help solve the problem or deal with the issue?