Illustrations from
BUILDING THE ULTIMATE DAM
Chapters One & Two
The upstream face of John S. Eastwood's Big Bear Valley
Dam
in Southern
California, constructed in 1910-1911.
This view shows
the characteristic
shape of a MULTIPLE ARCH dam in which the upstream surface of the
structure is formed by a series of arches. At the time this photo was
taken, Eastwood's dam was not impounding any water; as the reservoir
fills, gradually the arches will become inundated. And
when the reservoir level drops, the arches will become visible again.
The
vignette shows Eastwood circa 1912.
in Southern California, constructed in 1910-1911.
The downstream face of the Mountain Dell Dam,
near Salt Lake
City, completed 1925.
This view shows the characteristic shape of a BUTTRESS dam when viewed
from the downstream side. The arches of this Eastwood dam are supported
upon the individual buttresses which, in turn, rest upon bedrock
foundations. The structure is not a solid monolith extending across
the dam site. Instead it forms a highly articulated design with a
distinctive visual appearance.
Note how this appearance contrasts
with the next photo.
The downstream face of the Croton Dam north of New York City,
in Westechester County, completed in 1907.
This is a good
example of a massive gravity dam built using masonry. In contrast to the
multiple arch dam, which is designed to utilize as little construction
material as possible, gravity dams depend upon the enormous weight of the
structure to hold back the hydrostatic pressure exerted by the
reservoir.
Gravity dams can be extremely
expensive to build, but they were (and still are) considered by many
conservative engineers to be the most desirable type of dam.
Eastwood
considered this type of design to be wasteful and economically
inefficient.
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near Salt Lake City, completed 1925.
This view shows the characteristic shape of a BUTTRESS dam when viewed from the downstream side. The arches of this Eastwood dam are supported upon the individual buttresses which, in turn, rest upon bedrock foundations. The structure is not a solid monolith extending across the dam site. Instead it forms a highly articulated design with a distinctive visual appearance.
Note how this appearance contrasts with the next photo.
in Westechester County, completed in 1907.
This is a good example of a massive gravity dam built using masonry. In contrast to the multiple arch dam, which is designed to utilize as little construction material as possible, gravity dams depend upon the enormous weight of the structure to hold back the hydrostatic pressure exerted by the reservoir.
Gravity dams can be extremely expensive to build, but they were (and still are) considered by many conservative engineers to be the most desirable type of dam.
Eastwood considered this type of design to be wasteful and economically inefficient.
Return to the Illustrations Main Page.
Return to the Building the Ultimate Dam Main Page.