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Linking water and permafrost dynamics
Stockholm University, Faculty of Science, Department of Physical Geography.
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The extent and dynamics of permafrost are tightly linked to the distribution and movement of water in arctic landscapes. As the Arctic warms more rapidly than the global average, profound changes are expected in both permafrost and hydrology; however, much is still not known about the interactions between these two systems. The aim of this thesis is to provide new knowledge on the links between permafrost and hydrology under varying environmental conditions and across different scales. The objectives are to (i) determine how permafrost distributions and patterns in morphology are linked to hydrology, (ii) determine how groundwater flow influences ground temperature dynamics in permafrost landscapes, and (iii) explore the mechanisms that link permafrost to groundwater and streamflow dynamics. A range of methods have been applied within the four studies (papers I-IV) comprising the thesis: geophysical (ground penetrating radar and electrical resistivity tomography) and GIS techniques for mapping and analyzing permafrost distributions and related morphology; numerical modeling of coupled heat and water fluxes for mechanistic understanding permafrost-hydrological links; and statistical analyses for detecting trends in streamflow associated with permafrost thaw. Combining these various methods here allows for, and may be considered a prerequisite for, novel insights to processes. The thesis also presents statistical analyses of field observations of ground temperatures, ground- and surface water levels, as well as lake and shore morphological variables. Discontinuous permafrost peatlands are heterogeneous environments regarding permafrost distributions and thickness which is manifested in surface systems such as lake geometries. In these environments, lateral groundwater fluxes, which are not considered in most permafrost models, can significantly influence ground temperature dynamics, especially during high groundwater gradient conditions. River discharge data provide a potential for monitoring catchment-scale changes in permafrost, as the magnitude and seasonality of groundwater fluxes feeding into streams are affected by the distribution of permafrost. This thesis highlights the need to understand water and permafrost as an integrated system with potential internal feedback processes. For example, permafrost thaw can lead to increases in groundwater discharge which in turn can lead to increased heat transfer through the ground, resulting in further acceleration of permafrost thaw rates. 

Place, publisher, year, edition, pages
Stockholm: Department of Physical Geography, Stockholm University , 2015. , 28 p.
Series
Dissertations from the Department of Physical Geography, ISSN 1653-7211 ; 50
Keyword [en]
permafrost, hydrology, arctic, modeling, streamflow, geophysical measurements, ground thermal dynamics, groundwater
National Category
Oceanography, Hydrology, Water Resources Physical Geography
Research subject
Physical Geography
Identifiers
URN: urn:nbn:se:su:diva-116647ISBN: 978-91-7649-164-5 (print)OAI: oai:DiVA.org:su-116647DiVA: diva2:807133
Public defence
2015-06-12, De Geer-salen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.

Available from: 2015-05-21 Created: 2015-04-22 Last updated: 2015-06-23Bibliographically approved
List of papers
1. Geophysical mapping of palsa peatland permafrost
Open this publication in new window or tab >>Geophysical mapping of palsa peatland permafrost
2015 (English)In: The Cryosphere, ISSN 1994-0416, E-ISSN 1994-0424, Vol. 9, 465-478 p.Article in journal (Refereed) Published
Abstract [en]

Permafrost peatlands are hydrological and biogeochemicalhotspots in the discontinuous permafrost zone.Non-intrusive geophysical methods offer a possibility tomap current permafrost spatial distributions in these environments.In this study, we estimate the depths to the permafrosttable and base across a peatland in northern Sweden,using ground penetrating radar and electrical resistivitytomography. Seasonal thaw frost tables (at 0.5m depth),taliks (2.1–6.7m deep), and the permafrost base (at 16mdepth) could be detected. Higher occurrences of taliks werediscovered at locations with a lower relative height of permafrostlandforms, which is indicative of lower ground icecontent at these locations. These results highlight the addedvalue of combining geophysical techniques for assessing spatialdistributions of permafrost within the rapidly changingsporadic permafrost zone. For example, based on a back-ofthe-envelope calculation for the site considered here, we estimatedthat the permafrost could thaw completely within thenext 3 centuries. Thus there is a clear need to benchmark currentpermafrost distributions and characteristics, particularlyin under studied regions of the pan-Arctic.

Keyword
permafrost, ground penetrating radar, electrical resistivity tomography
National Category
Other Earth and Related Environmental Sciences
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-115888 (URN)10.5194/tc-9-465-2015 (DOI)000353878400004 ()
Available from: 2015-04-07 Created: 2015-04-07 Last updated: 2017-12-04Bibliographically approved
2. Thermokarst Lake Morphometry and Erosion Features in Two Peat Plateau Areas of Northeast European Russia
Open this publication in new window or tab >>Thermokarst Lake Morphometry and Erosion Features in Two Peat Plateau Areas of Northeast European Russia
2013 (English)In: Permafrost and Periglacial Processes, ISSN 1045-6740, E-ISSN 1099-1530, Vol. 24, no 1, 75-81 p.Article in journal (Refereed) Published
Abstract [en]

High-resolution satellite remote sensing analysis (n=637 lakes) and field measurements (n=29 lakes) of two peat plateau areas in northeast European Russia were carried out to investigate lake morphology, map shoreline erosion indicators and assess possible orientation patterns in lake and shore morphology. The study includes the first detailed characterisation of the shape and size of thermokarst lakes in organic terrain. The area covered by lakes is 7.0 per cent and 13.6 per cent, and median lake size is 184m2 and 265m2, respectively, for the two study areas. In both areas, most lakes have a similar northwest to southeast orientation, and shores most commonly face northeast or southwest. The shores are generally steeper and have more cracks and lake depths are greater along shores facing northeast or southeast, and along the shorelines of larger lakes. Shores with a peat substrate are more heterogeneous than those with a mineral substrate in terms of steepness, cracks and water depths. Since the lakes are generally small, the shoreline/area ratio is high and a large part of the peat plateau areas can potentially be affected by shoreline erosion.

Keyword
Peat Plateau, Thermokarst, Arctic Russia, Lake Shoreline Orientation, Shoreline Characteristics, Remote Sensing
National Category
Physical Geography Geology
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-89745 (URN)10.1002/ppp.1762 (DOI)000316623500007 ()
Funder
EU, European Research Council, 036993
Note

AuthorCount:3;

Available from: 2013-05-07 Created: 2013-05-06 Last updated: 2017-12-06Bibliographically approved
3. Thermal effects of groundwater flow through subarctic fens - a case study based on field observations and numerical modeling
Open this publication in new window or tab >>Thermal effects of groundwater flow through subarctic fens - a case study based on field observations and numerical modeling
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Oceanography, Hydrology, Water Resources Physical Geography
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-116645 (URN)
Available from: 2015-04-22 Created: 2015-04-22 Last updated: 2016-01-29Bibliographically approved
4. Using streamflow characteristics to explore permafrost thawing in northern Swedish catchments
Open this publication in new window or tab >>Using streamflow characteristics to explore permafrost thawing in northern Swedish catchments
2012 (English)In: Hydrogeology Journal, ISSN 1431-2174, E-ISSN 1435-0157, Vol. 21, no 1, 121-131 p.Article in journal (Refereed) Published
Abstract [en]

The recent and rapid warming of the Arcticleads to thawing of permafrost, which influences andchanges subsurface water-flow systems in such landscapes.This study explores the utility of catchments as“sentinels of change” by considering long-term dischargedata from 17 stations on unregulated rivers in northernSweden and analyzing trends in annual minimum dischargeand recession flow characteristics. For the catchmentsconsidered, the annual minimum discharge hasincreased significantly (based on the Mann Kendall test ata 95% confidence level) in nine of the catchments anddecreased significantly in one catchment. Consideringchanges in recession-flow characteristics, seven catchmentsshowed significant trends consistent with permafrostthawing while two catchments showed significanttrends in the opposite direction. These results aremechanistically consistent with generic physically basedmodeling studies and the geological setting, as thecatchments considered span the spatial limit of permafrostextent. This study illuminates the potential for usinghydrologic observations to monitor changes in catchmentscalepermafrost. Further, this opens the door for researchto isolate the mechanisms behind the different trendsobserved and to gauge their ability to reflect actualpermafrost conditions at the catchment scale.

Keyword
Groundwater–permafrost interactions, Groundwater/surface-water relations, Streamflowtrends, Sweden, Climate change
National Category
Climate Research
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-85211 (URN)10.1007/s10040-012-0932-5 (DOI)000314333600010 ()
Available from: 2013-01-07 Created: 2013-01-07 Last updated: 2017-12-06Bibliographically approved

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