Identification of groundwater exfiltration,interflow discharge,and hyporheic exchange flows by fibre optic distributed temperature sensing supported by electromagnetic induction geophysics |
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Authors: | Jaime Gaona Karin Meinikmann Jrg Lewandowski |
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Institution: | Jaime Gaona,Karin Meinikmann,Jörg Lewandowski |
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Abstract: | Water exchange across the sediment–water interface of streams impresses a characteristic thermal pattern at the interface. The use of fibre optic distributed temperature sensing at the sediment–water interface in a small sand‐bed stream identifies such temperature patterns. Groundwater and interflow can be differentiated based on the temporal evolution of temperature patterns. Additionally, sudden temperature changes at the sediment–water interface observed during the transit of floods enable spatial identification of local up and downwelling. Electromagnetic induction geophysics can detect subsurface texture structures that support groundwater–surface water exchange. Our results show that areas of permanent temperature anomalies observed with fibre optic distributed temperature sensing match areas of comparatively homogeneous electrical conductivity. This indicates groundwater discharge and enables differentiating groundwater discharge from interflow and local downwelling. |
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Keywords: | electromagnetic induction geophysics fibre optic distributed temperature sensing flood groundwater exfiltration hyporheic exchange flow interflow discharge sediment structure temperature anomaly |
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