Event Title

Winter Water Balance of a Semi-arid Bioretention Site During Plant Dormancy

Presenter Information

Austin Orr

Location

ECC 216

Event Website

http://water.usu.edu/

Start Date

4-3-2012 3:40 PM

End Date

4-3-2012 3:45 PM

Description

Understanding the hydrologic behavior of bioretention systems during months of plant dormancy is of particular concern in the semi-arid American West where most of the limited annual rainfall occurs in winter. In order to directly measure the water balance and obtain an estimate for evapotranspiration, three bioretention systems were established including: a noplant control, a native plant community that requires no additional irrigation in semi-arid climates, and an irrigated wetland community. Runoff events that represent the average precipitation regime were simulated once per month from October to April. By introducing a known quantity of water to the system and measuring the quantity of water flowing out, evapotranspiration was approximated. Fluctuations in soil storage were accounted for using time-domain reflectometry (TDR) and all systems were sealed to prevent infiltration. Effluent volume was measured directly using a tipping bucket and data logger. This spring, leaf level transpiration will be measured using a LI-COR 6400 infrared gas analyzer to better understand water use patterns. Testing continues on this project, and the data reported includes results for the winter of 2011-2012. Preliminary findings indicate that all of the water flowing into each garden flows is accounted for in the effluent to within 10 gallons. As expected, transpiration rates appear to be minimal during plant dormancy. This suggests that for bioretention sites in xeric climate regimes winter water losses will be due primarily to garden exfiltration and not plant processes.

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Apr 3rd, 3:40 PM Apr 3rd, 3:45 PM

Winter Water Balance of a Semi-arid Bioretention Site During Plant Dormancy

ECC 216

Understanding the hydrologic behavior of bioretention systems during months of plant dormancy is of particular concern in the semi-arid American West where most of the limited annual rainfall occurs in winter. In order to directly measure the water balance and obtain an estimate for evapotranspiration, three bioretention systems were established including: a noplant control, a native plant community that requires no additional irrigation in semi-arid climates, and an irrigated wetland community. Runoff events that represent the average precipitation regime were simulated once per month from October to April. By introducing a known quantity of water to the system and measuring the quantity of water flowing out, evapotranspiration was approximated. Fluctuations in soil storage were accounted for using time-domain reflectometry (TDR) and all systems were sealed to prevent infiltration. Effluent volume was measured directly using a tipping bucket and data logger. This spring, leaf level transpiration will be measured using a LI-COR 6400 infrared gas analyzer to better understand water use patterns. Testing continues on this project, and the data reported includes results for the winter of 2011-2012. Preliminary findings indicate that all of the water flowing into each garden flows is accounted for in the effluent to within 10 gallons. As expected, transpiration rates appear to be minimal during plant dormancy. This suggests that for bioretention sites in xeric climate regimes winter water losses will be due primarily to garden exfiltration and not plant processes.

https://digitalcommons.usu.edu/runoff/2012/Posters/28