In addition, water in its place, such as a lake, is important to our livelihood.
Besides its use in transportation, many recreational activities, such as swimming and
boating, depend upon lakes and streams. Further, lakes have an aesthetic quality.
Many poems and stories have been written about lakes. The beauty and tranquility of
lakes adds to our consolation. Storms on a lake inspire awe. Thus it may be seen that
lakes are essential to our way of life.
In this chapter, reservoirs are considered in the same manner as lakes. By
definition, reservoirs are artificial lakes, generally constructed to serve a specific
purpose. That purpose may include drinking water supply, flood control, low flow
augmentation, travel enhancement, storage for periods of low precipitation, recreation, and any combination of these. The life of a reservoir mimics that of a lake,
although the factors that influence the life of a reservoir may be somewhat different,
or in different magnitude, from those that impact the life of a lake. In both cases these
factors are so variable that to predict the life of a lake, each lake must be studied as its
own entity. No two lakes or reservoirs are exactly the same, nor have the same needs.
It may be concluded that the preservation of lakes and the extension of their lives
is important to the continuation of human life on Earth.
2 Characteristics of Lakes
Even though each lake has its own characteristics, we can make generalities on the
factors that influence the life of a lake or reservoir. By understanding these characteristics, we can devise means of slowing the aging process and in some cases even
reversing that process. By studying ancient lakes and terminal lakes, we can describe
the factors that have either preserved the lake or hastened its demise.
There are numerous factors that control the life of a lake. Not in any preferred
order, the morphology of a lake is an initial factor. Deep lakes with steep sides seem
to have greater longevity. Large shallow areas tend to encourage rooted plant
growth, which leads to the more rapid filling in of the lake. Steep sides may even
limit human habitation as experienced in Crater Lake, Oregon, formed in the caldera
of a former volcano. The smaller the ratio of the watershed to the lake surface area,
the longer its life; again Crater Lake is a prime example. Larger lakes such as the
Great Lakes of North America have a long life. The underlying geological formations in the lake may contribute essential nutrients that may allow biological growth.
A forested watershed will lessen the amount of nutrients being carried into the lake.
Conversely, farmed areas contribute large amounts of nutrients from fertilizers.
Human development may contribute significantly to the demise of a lake. Whereas
everyone enjoys the beauty and the recreation attractions of a lake, more inhabitants
result in more direct surface runoff to the lake and more domestic wastes containing
nutrients to ultimately reach the lake. A significant impact is lakeside homeowners
who pride themselves with their green lawns, right down to the water’s edge, kept
green with fertilizers, which readily reach the lake. Again, no two lakes are identical,
and the combination of factors affecting a lake’s life is infinite.
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L. K. Wang et al.
Besides its use in transportation, many recreational activities, such as swimming and
boating, depend upon lakes and streams. Further, lakes have an aesthetic quality.
Many poems and stories have been written about lakes. The beauty and tranquility of
lakes adds to our consolation. Storms on a lake inspire awe. Thus it may be seen that
lakes are essential to our way of life.
In this chapter, reservoirs are considered in the same manner as lakes. By
definition, reservoirs are artificial lakes, generally constructed to serve a specific
purpose. That purpose may include drinking water supply, flood control, low flow
augmentation, travel enhancement, storage for periods of low precipitation, recreation, and any combination of these. The life of a reservoir mimics that of a lake,
although the factors that influence the life of a reservoir may be somewhat different,
or in different magnitude, from those that impact the life of a lake. In both cases these
factors are so variable that to predict the life of a lake, each lake must be studied as its
own entity. No two lakes or reservoirs are exactly the same, nor have the same needs.
It may be concluded that the preservation of lakes and the extension of their lives
is important to the continuation of human life on Earth.
2 Characteristics of Lakes
Even though each lake has its own characteristics, we can make generalities on the
factors that influence the life of a lake or reservoir. By understanding these characteristics, we can devise means of slowing the aging process and in some cases even
reversing that process. By studying ancient lakes and terminal lakes, we can describe
the factors that have either preserved the lake or hastened its demise.
There are numerous factors that control the life of a lake. Not in any preferred
order, the morphology of a lake is an initial factor. Deep lakes with steep sides seem
to have greater longevity. Large shallow areas tend to encourage rooted plant
growth, which leads to the more rapid filling in of the lake. Steep sides may even
limit human habitation as experienced in Crater Lake, Oregon, formed in the caldera
of a former volcano. The smaller the ratio of the watershed to the lake surface area,
the longer its life; again Crater Lake is a prime example. Larger lakes such as the
Great Lakes of North America have a long life. The underlying geological formations in the lake may contribute essential nutrients that may allow biological growth.
A forested watershed will lessen the amount of nutrients being carried into the lake.
Conversely, farmed areas contribute large amounts of nutrients from fertilizers.
Human development may contribute significantly to the demise of a lake. Whereas
everyone enjoys the beauty and the recreation attractions of a lake, more inhabitants
result in more direct surface runoff to the lake and more domestic wastes containing
nutrients to ultimately reach the lake. A significant impact is lakeside homeowners
who pride themselves with their green lawns, right down to the water’s edge, kept
green with fertilizers, which readily reach the lake. Again, no two lakes are identical,
and the combination of factors affecting a lake’s life is infinite.
260
L. K. Wang et al.