Event Title

The Effects of Large-Scale Stream Rehabilitation on Transient Storage Dynamics: Implications for Hyporheic Exchange on the Provo River, Heber Valley, Utah

Location

Eccles Conference Center

Event Website

http://water.usu.edu/htm/conference/past-spring-runoff-conferences

Start Date

27-3-2006 6:00 PM

End Date

27-3-2006 6:15 PM

Description

Comparisons of rehabilitated and impaired reaches of the Provo River, Heber Valley, Utah suggest that channel reconfiguration increased the relative area of transient storage, but not the reach-average residence time of water in transient storage. Transient storage in a river is the process by which water advectively transported downstream is temporarily sequestered in low-velocity areas such as pools, eddies, or the subsurface. The latter storage zone is known as the hyporheic zone. Transient storage, in particular the hyporheic zone, plays a crucial role in the physical retention, and biogeochemical transformation, of nutrients such as nitrogen and dissolved organic carbon. Stream rehabilitation projects, such as the Provo River Restoration Project (PRRP), share the common goal of restoring the physical and biological integrity of impaired river systems. Considering the importance of transient storage, many researchers feel that understanding the role of channel reconfiguration in promoting storage processes may prove critical to rehabilitation success. We coupled hydrologic tracer tests with channel geometry and substrate measurements in 3 rehabilitated and 3 impaired reaches if the PRRP in order to determine the relative effects of channel reconstruction on solute residence time distribution, exchange rates between the stream and storage zones, and transient storage capacity. We hypothesized that rehabilitated reaches would display increased reach average residence times and storage capacities, and decreased average exchange rates. These changes would occur as a result of increased flux through longer hyporheic flowpaths. Geomorphic analysis suggests that rehabilitation has increased channel complexity, and enhanced features believed to control flow in the hyporheic zone. Tracer results agree with our hypothesis in that mean transient storage capacity in rehabilitated reaches was increased up to 2.86 times that of the mean impaired capacity. However, mean residence time in storage, and mean exchange rate were unaffected. We speculate that rehabilitation has increased flux through relatively short, fast exchange with channel and hyporheic storage zones, but has not significantly increased flux through longer subsurface flow paths.

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Mar 27th, 6:00 PM Mar 27th, 6:15 PM

The Effects of Large-Scale Stream Rehabilitation on Transient Storage Dynamics: Implications for Hyporheic Exchange on the Provo River, Heber Valley, Utah

Eccles Conference Center

Comparisons of rehabilitated and impaired reaches of the Provo River, Heber Valley, Utah suggest that channel reconfiguration increased the relative area of transient storage, but not the reach-average residence time of water in transient storage. Transient storage in a river is the process by which water advectively transported downstream is temporarily sequestered in low-velocity areas such as pools, eddies, or the subsurface. The latter storage zone is known as the hyporheic zone. Transient storage, in particular the hyporheic zone, plays a crucial role in the physical retention, and biogeochemical transformation, of nutrients such as nitrogen and dissolved organic carbon. Stream rehabilitation projects, such as the Provo River Restoration Project (PRRP), share the common goal of restoring the physical and biological integrity of impaired river systems. Considering the importance of transient storage, many researchers feel that understanding the role of channel reconfiguration in promoting storage processes may prove critical to rehabilitation success. We coupled hydrologic tracer tests with channel geometry and substrate measurements in 3 rehabilitated and 3 impaired reaches if the PRRP in order to determine the relative effects of channel reconstruction on solute residence time distribution, exchange rates between the stream and storage zones, and transient storage capacity. We hypothesized that rehabilitated reaches would display increased reach average residence times and storage capacities, and decreased average exchange rates. These changes would occur as a result of increased flux through longer hyporheic flowpaths. Geomorphic analysis suggests that rehabilitation has increased channel complexity, and enhanced features believed to control flow in the hyporheic zone. Tracer results agree with our hypothesis in that mean transient storage capacity in rehabilitated reaches was increased up to 2.86 times that of the mean impaired capacity. However, mean residence time in storage, and mean exchange rate were unaffected. We speculate that rehabilitation has increased flux through relatively short, fast exchange with channel and hyporheic storage zones, but has not significantly increased flux through longer subsurface flow paths.

http://digitalcommons.usu.edu/runoff/2006/AllAbstracts/38