Event Title

Effect of Dissolved Organic Carbon on Sediment Temperatures in Beaver Ponds

Presenter Information

Camilla Snow

Location

ECC 216

Event Website

http://water.usu.edu/

Start Date

4-3-2012 4:35 PM

End Date

4-3-2012 4:40 PM

Description

The Utah Division of Wildlife Resources has begun to implement a management plan to introduce beaver at different sites across the state of Utah in order to restore stream reaches; however there is little understanding of the impacts that beaver have on system biogeochemistry, temperatures, or hydrology. While it has been observed that beaver impoundments increase re186sidence times, change groundwater/surface water interactions, and change temperature distributions in streams, the specific impacts on individual processes influencing these system responses are unknown. More specifically, there is limited understanding of how changes in water chemistry may influence both water and sediment temperatures within streams. Studies have shown that beaver impoundments accumulate organic matter and as a result accumulate dissolved organic carbon (DOC) in the water. It is known that DOC absorbs portions of the incoming solar radiation spectrum and may contribute to the changing temperature distributions. To investigate the significance of changing DOC concentrations on shortwave radiation penetration of a water column, a study was conducted in a completely mixed tank filled with tap water. Concentrations of DOC from 2 mg/L to 15 mg/L were added to the tank while broad spectrum solar radiation was measured at different depths throughout the water column to estimate attenuation coefficients. From these data, a direct linear correlation between the broad spectrum attenuation coefficients and DOC concentrations was found. To compare these findings to natural stream conditions, a bed sediment temperature model was developed that accounts for conduction between the water column and deeper substrate while estimating the incoming radiation to the bed sediments based on DOC concentrations within the overlying water column. This model allows for the prediction of the effects of changing DOC concentrations and the associated impacts on stream bed temperatures for a case study location in Curtis Creek, UT. As would be expected, the model estimated that higher attenuation coefficients due to higher DOC concentrations resulted in significantly less radiation reaching the sediments and therefore, lowered stream bed temperatures. This means that significantly more energy is absorbed by the water column with increases in DOC concentration and the potential buffering of instream temperatures due to water column and streambed heat exchanges will differ. These findings also provide foundational information necessary to develop complete energy budgets for beaver dams while considering changing instream chemistry.

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Apr 3rd, 4:35 PM Apr 3rd, 4:40 PM

Effect of Dissolved Organic Carbon on Sediment Temperatures in Beaver Ponds

ECC 216

The Utah Division of Wildlife Resources has begun to implement a management plan to introduce beaver at different sites across the state of Utah in order to restore stream reaches; however there is little understanding of the impacts that beaver have on system biogeochemistry, temperatures, or hydrology. While it has been observed that beaver impoundments increase re186sidence times, change groundwater/surface water interactions, and change temperature distributions in streams, the specific impacts on individual processes influencing these system responses are unknown. More specifically, there is limited understanding of how changes in water chemistry may influence both water and sediment temperatures within streams. Studies have shown that beaver impoundments accumulate organic matter and as a result accumulate dissolved organic carbon (DOC) in the water. It is known that DOC absorbs portions of the incoming solar radiation spectrum and may contribute to the changing temperature distributions. To investigate the significance of changing DOC concentrations on shortwave radiation penetration of a water column, a study was conducted in a completely mixed tank filled with tap water. Concentrations of DOC from 2 mg/L to 15 mg/L were added to the tank while broad spectrum solar radiation was measured at different depths throughout the water column to estimate attenuation coefficients. From these data, a direct linear correlation between the broad spectrum attenuation coefficients and DOC concentrations was found. To compare these findings to natural stream conditions, a bed sediment temperature model was developed that accounts for conduction between the water column and deeper substrate while estimating the incoming radiation to the bed sediments based on DOC concentrations within the overlying water column. This model allows for the prediction of the effects of changing DOC concentrations and the associated impacts on stream bed temperatures for a case study location in Curtis Creek, UT. As would be expected, the model estimated that higher attenuation coefficients due to higher DOC concentrations resulted in significantly less radiation reaching the sediments and therefore, lowered stream bed temperatures. This means that significantly more energy is absorbed by the water column with increases in DOC concentration and the potential buffering of instream temperatures due to water column and streambed heat exchanges will differ. These findings also provide foundational information necessary to develop complete energy budgets for beaver dams while considering changing instream chemistry.

https://digitalcommons.usu.edu/runoff/2012/Posters/17