Event Title

Predicting the effect of beaver dams on stream thermal heterogeneity

Location

Eccles Conference Center

Event Website

http://water.usu.edu

Start Date

2-4-2014 6:15 PM

End Date

2-4-2014 6:30 PM

Description

Restoration of the beaver population (Castor Canadensis) to streams and rivers is desirable because they are a sustainable and lower cost method of improving stream habitat when compared to human-engineered restoration efforts. Prior studies have shown that beaver colonization results in impoundments of water which increase channel width and surface area, increase sediment deposition, and slow flow velocities. While these changes can create a thermally heterogeneous environment promoting diverse aquatic communities and providing thermal refugia, there is a need to understand the spatial distribution of temperatures and to identify characteristics that produce this variability. To address these needs we developed a process-based temperature model for a beaver pond within Curtis Creek, UT. Using water temperature data distributed spatially within the pond, we delineated model segments into areas with similar temperature responses. This resulted in a main channel area and three surface transient storage (STS) zones– one of which was further segmented into two layers where thermal stratification was present. Onsite discharge, water temperature, sediment temperature, channel geometry, and meteorological data provided information for model inputs and calibration. The model formulation accounts for advection, heat fluxes at the air-water interface, lateral exchange between zones, vertical exchange between stratified layers, attenuation of shortwave radiation within the water column, and streambed conduction. The model captured each zone’s instream and sediment temperatures well and provided information regarding the dominant heat fluxes for each zone. These results can lead to insight regarding key processes and characteristics driving the thermal heterogeneity within beaver ponds over both space and time. Ultimately, this type of modeling approach can aid in future decisions regarding restoring beaver to certain stream systems and the associated ecological implications.

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Apr 2nd, 6:15 PM Apr 2nd, 6:30 PM

Predicting the effect of beaver dams on stream thermal heterogeneity

Eccles Conference Center

Restoration of the beaver population (Castor Canadensis) to streams and rivers is desirable because they are a sustainable and lower cost method of improving stream habitat when compared to human-engineered restoration efforts. Prior studies have shown that beaver colonization results in impoundments of water which increase channel width and surface area, increase sediment deposition, and slow flow velocities. While these changes can create a thermally heterogeneous environment promoting diverse aquatic communities and providing thermal refugia, there is a need to understand the spatial distribution of temperatures and to identify characteristics that produce this variability. To address these needs we developed a process-based temperature model for a beaver pond within Curtis Creek, UT. Using water temperature data distributed spatially within the pond, we delineated model segments into areas with similar temperature responses. This resulted in a main channel area and three surface transient storage (STS) zones– one of which was further segmented into two layers where thermal stratification was present. Onsite discharge, water temperature, sediment temperature, channel geometry, and meteorological data provided information for model inputs and calibration. The model formulation accounts for advection, heat fluxes at the air-water interface, lateral exchange between zones, vertical exchange between stratified layers, attenuation of shortwave radiation within the water column, and streambed conduction. The model captured each zone’s instream and sediment temperatures well and provided information regarding the dominant heat fluxes for each zone. These results can lead to insight regarding key processes and characteristics driving the thermal heterogeneity within beaver ponds over both space and time. Ultimately, this type of modeling approach can aid in future decisions regarding restoring beaver to certain stream systems and the associated ecological implications.

http://digitalcommons.usu.edu/runoff/2014/2014Abstracts/30