Investigation of Evapotranspiration in a Bioretention System through Soil Moisture Content

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2019-03-25
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Abstract
Bioretention systems control stormwater runoff through infiltration, groundwater recharge, and water loss via evapotranspiration (ET) processes. The significance of ET as a volume reduction method has been limited in research. This study at a University of Calgary research facility in Okotoks, Alberta, assessed ET in the “40” soil media bioretention system. Soil moisture content sensors installed at 20cm and 40cm depths provided ET estimates. Seasonality impacted ET with the highest estimations occurring in July 2018 and the lowest in September 2018. 20cm ET estimations were generally higher than 40cm ET estimations due to shallow vegetation root systems. ANOVA tests showed woody, herbaceous, and turf grass vegetation types were not significant at 20cm on ET while woody and turf grass vegetations were significant at 40cm. The Hargreaves and Penman-Monteith equations do provide suitable upper and lower limits of ET estimation at 20cm. ET, at 20cm, reduced over 100% of water volumes and was capable of reducing antecedent moisture content in smaller storm events; 26 – 60% of water volumes were reduced in large storm events. At 40cm, ET reduced between 21 – 67% and over 100% of water volumes and was capable of slightly reducing antecedent moisture content in smaller events; 0-50% of water volumes were reduced in large storm events.
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Nadori, R. (2019). Investigation of evapotranspiration in a bioretention system through soil moisture content (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.