Least tern. Artwork
provided by Missouri Department of Conservation.
Modeling the creation
of islands in a stream: Within a 6-foot-wide flume, sediment accumulates
behind a V-shaped rock formation and the barrier upstream of
Paul R. Weckler, Oklahoma State University.
ARS Flume Shows "V" in River May Aid
Endangered Tern By Luis Pons
The interior least tern (Sterna antillarum), an
endangered species that nests on sandbars within rivers, may get a boost from a
cooperative effort between students at Oklahoma State University (OSU) and
scientists with the Agricultural Research
Three seniors in OSU's
of Biosystems and Agricultural Engineering sought to increase nesting
habitats for these birds by tweaking river flow so that it would steer sediment
to form new, small islands. The students---Mary Crawford, Matthew Simpson and
Scott Schneider--used computers to portray how stone formations and other
structures could help produce this effect.
To field-test their theory, they looked to the ARS
Research Unit in Stillwater, Okla. The unit is recognized worldwide for
modeling, designing and engineering hydraulic structures. Using scale models,
its researchers can create for study a multitude of erosion and bridge- and
The OSU students--aided by ARS researchers Sherry Britton, a
hydraulic engineer, and Kem Kadavy, an agricultural engineer--used the
facility's 6-foot-wide flume to find the best formations that would create the
islands. The flume has a scale of about 1:100 in comparison to large rivers.
They found that an inverted "V" shape with a barrier behind it
worked best at slowing flow enough to trap sediment and eventually create an
island. According to OSU assistant professor Paul Weckler, who oversaw the
project, this design is being considered for inclusion in upcoming improvements
that Tulsa, Okla., will make to the Arkansas River, a major nesting site for
the interior least tern.
The class project was initiated by the U.S. Army Corps of
Engineers' Tulsa district office.
Once abundant, interior least terns were spotted frequently by
Lewis and Clark during their 1804 expedition. But their numbers dropped, first
due to a demand for their skins for women's hats in the 1890s, and later
because of damming and channelization of waterways.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.