Lesson 2_ Ground Water Supplies
Transcript of Lesson 2_ Ground Water Supplies
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Lesson 2:
Water Supplies
Groundwater Supplies
Underground water is supposed to be the purest form of natural water. Sometimes, itis so pure that it does not need any further treatment for drinking purposes. It is the
least contaminated and has very low turbidity due to natural filtration of the rain water.
It can be contaminated by underground streams in areas with limestone deposits,
septic tanks discharge, and underground deep well leaks. Therefore, it may need
disinfection. It needs only mineral removal treatment when compared to surface water
supplies. It contains more dissolved minerals such as calcium, magnesium, iron,
manganese and sulfur compounds than the surface supply. There are two sources of
groundwater: springs and wells.
If you dig a hole down through the earth, the soil initially has pockets of air betweenthe soil particles. But as you dig deeper, soon water would fill in all of the gaps in the
soil. The location where all of the holes first become filled with water is called the
water table. This is the upper limit of the zone of saturation, also known as an aquifer,
which is the part of the earth containing the groundwater.
The bottom of the zone of saturation is marked by an impermeable layer of rocks,
clay or other material. Water cannot soak through this layer, so it instead slowly flows
downhill.
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Springs
Whenever an aquifer or an underground channel reaches the ground surface such as a
valley or a side of a cliff, water starts flowing naturally. This natural flow is known as
aspring. A spring may form a lake, a creek, or even a river. The quantity and velocity
of a spring flow depend on the aquifer size and the position of the spring relative to the
highest level of the water table. Regions with limestone deposits have large springs as
the water flows in underground channels, formed by the erosion of limestone. Thequality of the water depends on the nature of the soil through which the water flows.
For example, a mineral spring has dissolved minerals, a sulfur spring has dissolved
sulfur.
Wells
Public groundwater supply is usually well water because springs are rare. A well is a
device to draw the water from the aquifer. Deeper wells (more than 100 feet) have
less turbidity, more dissolved minerals, and less bacterial count than shallow wells.
Shallow wells have less natural filtration of water due to less depth of the soil.
Small rural communities (less than 25,000 populations) generally use the groundwater
from wells. About 35% of the American population uses groundwater supply.
Review
There are two main water suppllies used for consumption: surface water and
groundwater. Surface waters include calm waters, such as lakes and reservoirs, and
running water, such as a river or stream. Factors affecting calm water quality include
several factors, such as temperature, sunlight, turbidity, dissolved gases and nutrients.
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Factors affecting running water supplies are much smaller than those affecting lakes
and reservoirs. The only factors affecting running water is current and nutrients.
Underground water is supposed to be the purest form of natural water. Sometimes, it
is so pure that it does not need any further treatment for drinking purposes. It is the
least contaminated and has very low turbidity due to natural filtration of the rain water.
The two main supplies of groundwater are springs and wells. Whenever an aquifer or
an underground channel reaches the ground surface such as a valley or a side of a cliff,
water starts flowing naturally. This natural flow is known as aspring. A well is a
device to draw the water from the aquifer. Deeper wells (more than 100 feet) have
less turbidity, more dissolved minerals, and less bacterial count than shallow wells.
Assignment
Complete Assignment 2on Water Supplies. You may do the Assignment online to get
credit or print it out and send it to the instructor.
Quiz
Answer the questions inthe Lesson 2 quiz . When you have gotten all the answers
correct, print the page and either mail or fax it to the instructor. You may also takethe quiz online and submit your grade directly into the database for grading purposes.
http://water.me.vccs.edu/courses/env110/quiz2.htmhttp://water.me.vccs.edu/courses/env110/assignment2.htm