Outdoor StreamLab Image Gallery
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| The Outdoor StreamLab is located in the heart of Minneapolis, adjacent to St. Anthony Falls. This spring, a single sinuous meandering channel was installed within the first basin (the Riparian Basin) of the Outdoor StreamLab. In the background are the Stone Arch Bride, the Guthrie Theater, and the Mill City Museum. |
The Outdoor StreamLab is easily visible from the Stone Arch Bridge. The research area consists of the stream channel, its floodplain, and the 4-ft deep subsurface volume. The basin has a flexible design that allows the possible future installation of multiple stream channels, dams, in-stream structures, and bridge piers. |
Visitors to the Water Power Park can view researchers at work in the OSL. The SAFL building is visible on the left side of the image; the OSL webcam is perched on its roof. On the right side of the photograph is the second basin of the OSL, which in the near future will be developed into an even larger river research facility. |
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| A total station was used to stake out the horizontal position and vertical elevations of the channel and floodplain and to determine how erosion and deposition sculpt the bed and banks over time. |
158 piezometers were installed to allow the sampling of the hydraulic head, permeability, and subsurface water quality throughout the basin. |
Researchers obtain water samples from the piezometers to compare nutrient processing and subsurface residence time. |
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| The stream was constructed with a flat bed, but over the course of multiple floods point bars were produced on the inside of meander bends. |
Vegetation was planted on one of the banks to study its effect on sediment deposition. |
Researchers collected macroinvertebrates that colonized the riffle regions. A variety of taxa were observed, including Diptera, Ephemeroptera, and Trichoptera. |
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| Bridges over the riffle regions allow non-invasive access to important sites of biological activity. |
The stream channel is large by laboratory standards yet still small enough to permit instrumentation bridges, such as this velocity probe mounted on a computer-controlled lateral traverse. |
Researchers also used field probes to measure velocities within the channel. Plans are underway to develop an automatic measurement and access platform, an instrument bridge that would enable measurements to be obtained without disturbing the stream or floodplain areas. |
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| During the summer of 2008 suspended sediment was released halfway down the channel. Researchers compared upstream riffle regions (as a control) to downstream riffle regions. |
Researchers monitored particle sizes in the stream, upstream and downstream of the turbidity release. |
Fish cages were installed at the upstream and downstream ends of the channel to study the effects of sediment loading on smallmouth bass and white suckers. |
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The National Center for Earth-surface Dynamics (NCED) Stream Restoration Certificate Program used the OSL as the design focus of their capstone project. In addition to developing plans, certificate program students got their hands dirty installing coconut fiber matting to stabilize stream banks. |
Students also practiced giving directions to the operator of heavy equipment. Here, they direct a backhoe placing riprap at the downstream end of the stream channel. |
Vinyl sheet pile has been installed around the entire basin area to prevent groundwater leakage, thus enabling the study of interactions between ground water and surface water. |
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Fertile topsoil from a local agricultural field was tilled into the top of the sand surface to better support a native plant community. |
Hand-planted near-bank vegetation consists of a mix of plugs of native sedges and rushes. The rest of the floodplain area has been seeded with a native prairie seed mix. |
In late August the floodplain was seeded and covered with straw. The vegetation will provide bank stability during overbank floods in 2009. |
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The water flow rate (discharge) into the basin is continuously monitored using sonar. Valves allow control of the rate at which water flows under gravity out of the Mississippi River and into the basin. |
The sediment recirculation system can transport sediment up to 0.7 cm in diameter. The sediment is then separated into separate sand and gravel stockpiles for controlled feed into the system. |
At the downstream end, the channel water passes through a sediment settling basin before returning to the river. |
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| Collaboration between SAFL, NCED, and Xcel led to the repurposing of two abandoned flood-bypass relief spillways adjacent to the St. Anthony Falls. |
Water has been continuously flowing through the Riparian Basin of the Outdoor StreamLab since June 19, 2008. |
Biological colonization of the stream channel was swift. The attached algae Fragilaria had already started to colonize the submerged portions of the banks and the riffle regions 3 days after the stream water was turned on. The high natural light levels outside were responsible for shortening the colonization time to one tenth of what had been observed in previous indoor SAFL experiments using the same water source. |
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This photo was taken not long after the St. Anthony Falls Laboratory was built in 1938. The old flood relief spillways (now the OSL) are adjacent to the lab. |
Aerial view of the St. Anthony Falls, stone arch bridge, the upper lock, and the old flood relief spillways shortly before they were abandoned circa 1967. |
A close-up of the flood relief spillway aprons from behind SAFL's volumetric tanks. |
| To view a current image of the OSL (refreshed every 30 minutes), click here. To return to the OSL main page, click here. |
