Of Gravel and The River
of the same rivers year after year. Jacobson and his apprentice, Rose McKenney, a graduate student who also works for the USGS, have become experts on the Little Piney and Jacks Fork rivers and the Buffalo River in Arkansas.
To support this detailed research, the Conservation Department has cooperated with the USGS, the National Park Service, which administers three rivers as parks in the Ozarks, and the National Biological Service, a new federal agency. In the Ozarks the NBS has focused its Global Change Research Project on rivers, because our streams may be impacted by changing weather and other variations in the future. The NBS is also helping fund a closely related study of fish and changing Ozark rivers.
"These different sites we're studying have a variety of river habitats," McKenney points out as we work. "Riffles, runs and pools are affected by floods and other factors. We're surveying how and why river channels change over time."
A native of the Pacific Northwest, McKenney says she particularly enjoys how Ozark rivers vary with each season. "By the end of August in places they're like little bitty caves under all the green limbs. We don't have that so much out West."
Her dissertation will focus on how and why river habitats change. Her special interest is bluffs, which tend to form deep pools, a favorite habitat for bass.
We worked near Alley Spring to measure some 20 cross-sections. Once rope and survey line are run across, the surveyor sets up the theodolite on shore at one end of the line. The other person holds a stake topped with a special target and stops at about each meter marked along the line.
This allows the instrument to record the depth of the river channel at intervals along the line. By comparing data from all 20 cross sections, Jacobson and McKenney can see how this half mile of the Jacks Fork has changed over time and in relation to many variables, such as floods, river bed materials and surrounding vegetation.
Stringing heavy nylon rope from one bank to the other side, I tried to stay ahead of Robb and Rose. A three person crew can do about seven or eight cross-sections a day, fewer if deep water makes a boat necessary.
As a survey-rope runner I learned its difficulties: stakes get covered by flood-borne sediments; a line of sycamores at the edge of a gravel bar makes it nearly impossible to