lesson 2_ ground water supplies

7/28/2019 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

lesson 2_ ground water supplies

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