Impact of permafrost dynamics on Arctic groundwater ow systems with application to the evolution of spring and lake taliks
Groundwater ow in permafrost is restricted to unfrozen zones, known as taliks. There is an interaction between groundwater ow and heat ow, because the permafrost distribution determines the occurrence of groundwater, but groundwater also contributes to advective heat transport in uencing the distrib...
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| Format: | Thesis |
| Language: | English |
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2013
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| Online Access: | https://ueaeprints.uea.ac.uk/id/eprint/48711/ https://ueaeprints.uea.ac.uk/id/eprint/48711/1/ThesisJohannaScheidegger.pdf |
| Summary: | Groundwater ow in permafrost is restricted to unfrozen zones, known as taliks. There is an interaction between groundwater ow and heat ow, because the permafrost distribution determines the occurrence of groundwater, but groundwater also contributes to advective heat transport in uencing the distribution of permafrost. However, the advective heat ow component is small where the hydraulic gradient is low, or where recharge is limited. Conversely, where recharge is not driven by precipitation, as for example found under a wet based glacier, groundwater uxes can be more signi�cant. This thesis aims to improve understanding of the impacts of permafrost dynamics on Arctic groundwater ow systems for past and predicted climate change. Numerical modelling of coupled heat and uid ow including phase change of water/ice is used to study di�erent environments; lakes in a periglacial environment, and lakes and springs in a proglacial terrain. Results show that the transient e�ects of heat storage can in uence the present day distribution of permafrost. This is especially pronounced underneath surface water bodies, where there are cases for which under a steady state scenario no through talik is expected, but there are through taliks under a transient scenario. In addition, heat advection by groundwater ow can in uence the permafrost distribution by permafrost erosion and aggregation. The magnitude of heat advection is driven by topographically driven groundwater ow and the release of groundwater from elastic storage. The latter is signi�cant in previously glaciated areas that have undergone a large change in hydraulic head over time. In partially frozen ground, the choice of the permafrostpermeability- reduction function is crucial to quantify groundwater ow and advective heat ow. The occurrence of through taliks is in uenced by the regional scale groundwater ow, but taliks also in uence the regional scale hydrogeologic system by reversal of the general groundwater ow direction. |
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