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| Titel |
Shallow groundwater thermal sensitivity to climate change and land cover disturbances: derivation of analytical expressions and implications for stream temperature modeling |
| VerfasserIn |
B. L. Kurylyk, K. T. B. MacQuarrie, D. Caissie, J. M. McKenzie |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 19, no. 5 ; Nr. 19, no. 5 (2015-05-26), S.2469-2489 |
| Datensatznummer |
250120721
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| Publikation (Nr.) |
 copernicus.org/hess-19-2469-2015.pdf |
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| Zusammenfassung |
Climate change is expected to increase stream temperatures and the
projected warming may alter the spatial extent of habitat for cold-water fish
and other aquatic taxa. Recent studies have proposed that stream thermal
sensitivities, derived from short-term air temperature variations, can be
employed to infer future stream warming due to long-term climate change.
However, this approach does not consider the potential for streambed heat
fluxes to increase due to gradual warming of the shallow subsurface. The
temperature of shallow groundwater is particularly important for the thermal
regimes of groundwater-dominated streams and rivers. Also, recent
studies have investigated how land surface perturbations,
such as wildfires or timber harvesting, can influence stream temperatures by
changing stream surface heat fluxes, but these studies have typically not
considered how these surface disturbances can also alter shallow groundwater
temperatures and streambed heat fluxes.
In this study, several analytical solutions to the one-dimensional unsteady
advection–diffusion equation for subsurface heat transport are employed to
estimate the timing and magnitude of groundwater temperature changes due to seasonal and
long-term variability in land surface temperatures. Groundwater thermal
sensitivity formulae are proposed that accommodate different surface warming
scenarios. The thermal sensitivity formulae suggest that shallow groundwater
will warm in response to climate change and other surface
perturbations, but the timing and magnitude of the subsurface warming depends on the
rate of surface warming, subsurface thermal properties, bulk aquifer depth,
and groundwater velocity. The results also emphasize the difference between
the thermal sensitivity of shallow groundwater to short-term (e.g., seasonal)
and long-term (e.g., multi-decadal) land surface-temperature
variability, and thus demonstrate the limitations of using short-term air
and water temperature records to project future stream warming. Suggestions
are provided for implementing these formulae in stream temperature models to
accommodate groundwater warming. |
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