Independent component analysis of local-scale temporal variability in sediment-water interface temperature
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| Authors: | Middleton, MA; Whitfield, PH; Allen, DM |
| Year: | 2015 |
| Journal: | Water Resour. Res. 51: 9679-9695 Article Link (DOI) |
| Title: | Independent component analysis of local-scale temporal variability in sediment-water interface temperature |
| Abstract: | Temperature recorded at the sediment-water interface has been identified as a valuable tracer for understanding groundwater-surface water interactions. However, factors contributing to the variability in temperatures can be difficult to distinguish. In this study, the temporal variability in daily temperatures at the sediment-water interface is evaluated for a 40 m reach of a coastal stream using Independent Component Analysis (ICA). ICA separation is used to identify three independent temperature components within the reach for each of four summer periods (2008-2011). Extracted temperature signals correlate with stream discharge, estimated streambed temperature, and groundwater level, but the strength of the correlations varies from summer to summer. Overall, variations in the temperature signals have clearer separation in summers with lower stream discharge and greater stream temperature ranges. Surface heating from solar radiation is the dominant factor influencing the sediment-water interface temperature in most years, but there is evidence that thermal exchanges are taking place other than at the air-water interface. These exchanges take place at the sediment-water interface, and the correlation with groundwater levels indicates that these heat exchanges are associated with groundwater inflow. This study demonstrates that ICA can be used effectively to aid in identifying component signals in environmental applications of small spatial scale. |
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