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I Ridefelt H., Boelhouwers J., 2006, Observations on regional variations in solifluction landform morphology and environ- ment in the Abisko region, northern Sweden. Permafrost and Periglacial Processes, 17, 253–266. II Ridefelt H., Etzelmüller B., Boelhouwers J., Jonasson C., 2008 Statistic-empirical modelling of mountain permafrost in the Ab- isko region, sub-Arctic northern Sweden. Norsk Geografisk Tidskrift, 62, 278-289. III Ridefelt, H., Boelhouwers, J., Eiken, T., 2009, Measurement of solifluction rates using multi-temporal aerial photography. Earth Surface Processes and Landforms, 34, 725-737. IV Ridefelt H., Åkerman J., Beylich AA., Boelhouwers J., Kol- strup E., Nyberg R., in press, 56 years of solifluction measure- ments in the Abisko Mountains, northern Sweden – analysis of spatial and temporal variations of slow soil surface movements. Geografiska Annaler. V Ridefelt H., Etzelmüller B., Boelhouwers J., Spatial analysis of solifluction landforms and process rates in the Abisko Moun- tains, northern Sweden. Submitted to Permafrost and Perigla- cial Processes (under revision). VI Ridefelt H., Etzelmüller B., Boelhouwers J., Local variations of solifluction activity in the Abisko Mountains, northern Sweden. Manuscript. Reproduction of the published papers is made with kind permission from the copyright holders: Paper I and III © John Wiley & Sons Ltd. Paper II © Routledge Francis & Taylor Group Paper IV© Blackwell Publishing My contributions to the papers Paper I: Field work, data analysis, writing and discussion in collaboration with Jan Boelhouwers. Paper II: All field work and major part of the writing. Data analysis and discussion in collaboration with co-authors. Paper III: Idea and data analysis, part of the writing and discussion. Photo- grammetrical analysis in collaboration with Trond Eiken. Paper IV: Idea and all data analysis, most of the writing and discussion. Paper V: Part of the idea. Data analysis in collaboration with Bernd Et- zelmüller. Most of the writing. Paper VI: Idea in collaboration with Jan Boelhouwers. Most of the field work, data analysis and writing. Contents 1. Introduction ................................................................................................. 9 2. Characteristics of solifluction ................................................................... 11 2.1 The mechanisms of solifluction ......................................................... 11 2.2.1 Frost creep .................................................................................. 11 2.2.3 Gelifluction ................................................................................. 12 2.3 Solifluction landforms ........................................................................ 12 2.4 Environmental and climatic controls on solifluction processes ......... 13 2.4.1 Ground climate ........................................................................... 14 2.4.2 Permafrost ................................................................................... 16 2.4.3 Topography ................................................................................. 16 2.4.4 Vegetation and soil texture ......................................................... 17 3. The Abisko region ..................................................................................... 19 4. Methods .................................................................................................... 22 4.1 Field measurements ............................................................................ 22 4.1.1 Landform morphometry .............................................................. 22 4.1.2 Grids for solifluction measurements at a local scale .................. 22 4.1.3 Permafrost assessment ................................................................ 23 4.2 GIS-derived environmental parameters .............................................. 23 4.3 Assessment of long-term movement rates using aerial photography . 24 4.4 Compilation of solifluction data from the Abisko region .................. 25 4.5 Statistical methods .............................................................................. 25 4.6 Regionalization of movement rates .................................................... 26 4.7 Geomorphic work ............................................................................... 26 5. Results ....................................................................................................... 27 5.1 Solifluction movement rates ............................................................... 27 5.2 Permafrost assessment ........................................................................ 28 5.3 Environmental controls on solifluction .............................................. 31 5.4 Regionalization of movement rates .................................................... 32 5.5 Geomorphic work ............................................................................... 33 6. Discussion ................................................................................................. 35 6.1 Regional and local scale – similarities and differences ...................... 35 6.2 Comparisons between the different methods ..................................... 36 6.3 Knowledge and methods .................................................................... 37 6.4 Future outlook .................................................................................... 38 7. Conclusions ............................................................................................... 40 Acknowledgements ....................................................................................... 43 Sammanfattning ............................................................................................ 45 References ..................................................................................................... 48 1. Introduction Environmental controls, spatial and temporal variability in solifluction movement rates and landform distribution are addressed in this thesis based on field studies in the Abisko region, northern Sweden. Solifluction is gener- ally considered the most widespread form of slope movement in cold regions and attains surface movement rates in the order of a few cm per year (French, 2007; Matsuoka, 2001). Studies on slow mass wasting processes have largely focused on move- ment, mechanisms, internal structure or climatic significance and detailed point-specific monitoring, involving studies at the micro- and meso-scale (e.g. Thorn, 2003). Generally, issues related to spatial scale have been neg- lected in contemporary periglacial geomorphology (e.g. Gamble and Meen- temeyer, 1996; Thorn, 2003). Concerns of current climate change impacts on periglacial regions necessitate landscape-scale assessment of solifluction rates on decadal time-scales and methodological challenges for solifluction movement detection (Matsuoka, 2006). On a regional scale, changes in solif- luction movement rates can be expected to have an impact on sediment ero- sion, storage and sedimentation patterns on slopes and on sediment budgets (Ridefelt and Boelhouwers, 2006). However, complex interactions between ground climate, snow, slope hydrology and vegetation and their influence on solifluction at different scales complicate prediction of solifluction responses to climate change. Also, Harris (1993) suggests that the solifluction activity responses to climate change may be highly site specific. A further considera- tion in solifluction movement assessment is the small annual movement and a potentially large inter-annual variability, which necessitates long monitor- ing periods (Smith, 1992). There are a limited number of studies of variations of solifluction occur- rence and movement rates on a catchment or regional scale (e.g. Rapp, 1960; Price, 1973; Smith, 1987; Douglas and Harrison, 1996; Berthling et al., 2002). The results from these studies show that in general solifluction occur- rence and activity vary within the study areas. It is therefore difficult to draw conclusions about the solifluction activity for a larger region based on a li- mited number of measurements. To address this problem, approaches within Geographical Information Systems (GIS) and remote sensing, in combina- tion with statistical analysis, have
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