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Colorado School of Mines (2015)

Determining the influence of transpiration on soil moisture pathways using electrical resistivity imaging

Feist, Rachel A

Titre : Determining the influence of transpiration on soil moisture pathways using electrical resistivity imaging

Auteur : Feist, Rachel A

Université de soutenance : Colorado School of Mines

Grade : Master of Science (MS) 2015

Résumé
Many hydrologic models assume the vegetation and streamflow are fed by the same source of water, but isotopic studies have shown this is not always the case, especially in semi-arid climates. We investigate how soil moisture pathways are affected by daily transpiration using time-lapse electrical resistivity imaging (ERI) on a ponderosa pine and the surrounding soil during the growing season. By comparing sapflow measurements to the ERI data, we find that high periods of sapflow within the diel cycle are aligned with decreases in ground conductivity and soil moisture due to drying out of the soil during uptake. As the sapflow slows during the night, the ground conductivity increases as the soil is replenished. The mean and variance of the ground conductivity decreases into the summer dry season, describing drier soil and smaller diel fluctuations as the summer progresses. Sapflow does not significantly decrease through the summer, however, suggesting use of a deeper water source to maintain sapflow in a time of soil moisture depletion. ERI successfully captured spatiotemporal variability of soil moisture on daily and seasonal timescales, and with further research could be used to monitor temporal changes in tree water content.

Mots clés : Ecology, Geophysics, Earth sciences, Biological sciences, Hydrologic sciences

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Page publiée le 14 novembre 2015, mise à jour le 21 décembre 2017