In the above picture, you see the
Karluk River Weir, in Kodiak Alaska (photo courtesy of Tyler Polum).
The weir is supported by a series of tripods supporting panels of fence-like material all across the weir.
The phyics of the fluids interacting and exerting forces on the tripods, against the current, and the river
mechanics that accompany this science are simply fascinating!
The weir is supported by a series of tripods supporting panels of fence-like material all across the weir.
The phyics of the fluids interacting and exerting forces on the tripods, against the current, and the river
mechanics that accompany this science are simply fascinating!
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What
is a Weir?
In layman's terms, a Weir is a
fence that spans across an
entire river. It is constructed of tripods
made out of wood,
supportive bars, and panels of fence-like material
that allow the water to flow easily between the bars on the panels
while still preventing fish from swimming upstream. Weirs have
fish-blocking bars, but they also have gates that can be opened to
allow fish to swim through while a fish-counter (a summer employee for
the department) stands on the weir and simultaneously counts the number
of fish through and identifies species of salmon .Why would you fence a river off? Well, the Alaska Department of Fish and Game adopted this technique for monitoring the migration of fish upstream. Each summer, hundreds of weirs are constructed in various places around the state for the specific purpose of counting exactly how many of each species of salmon, trout, or other anadromous fish go upstream to spawn in the lakes. This collection of information allows Fish and Game biologists to determine how many fish can be expected in future years. |