Holocene colluvial (debris‐flow and water‐flow) processes in eastern Norway: stratigraphy, chronology and palaeoenvironmental implications

Abstract

Very little is known about the temporal pattern and the palaeoenvironmental implications of Holocene colluvial processes (debris‐flow and water‐flow processes) in eastern Norway. In this study, well‐dated sedimentary successions from 19 deep excavations are used to reconstruct Holocene colluvial activity in upper Gudbrandsdalen, eastern Norway. Following deglaciation, debris‐flow and water‐flow events have been common in upper Gudbrandsdalen throughout the Holocene, with 62% of the recognised debris‐flow and water‐flow units deposited prior to 5000 cal. yr BP. Relatively high colluvial activity is recorded at ca. 8600–7400, 2400–1900 and 800–400 cal. yr BP, with a conspicuous peak at ca. 8500–8100. Periods of relatively low colluvial activity are recorded at ca. 7100–6500, 5900–5300 and 3500–2500 cal. yr BP. Two different weather situations, unusually heavy rains and warm periods during the snowmelt season, are responsible for triggering colluvial processes in this area. These different weather situations may in turn be related to different climatic conditions. Copyright © 2007 John Wiley & Sons, Ltd.

Spatial and temporal variations of Norwegian geohazards in a changing climate, the GeoExtreme Project

“…Nevertheless, the area is also known for its floods and accompanying shallow landslides and debris flows. Existing debris flow data (Sletten, 2002;Sletten and Blikra, 2007) show a probability of about 1 event each 500-1000 years in most of the flow tracks. An important task is to evaluate the probability of a new major event, equivalent to the devastating landslides during the "Storofsen" flood in 1789, in a future climate regime.…”

A Holocene record of snow-avalanche and flood activity reconstructed from a lacustrine sedimentary sequence in Oldevatnet, western Norway

“…These two major glaciers contribute with large amounts of glacial meltwater to the southern lake basin, whereas the northern basin receives meltwater mainly from smaller, local glaciers. The outer limit of the Younger Dryas (YD) glaciation was situated at Nordfjordeid, approximately 40 km west of Oldevatnet, whereas Inset map of southern Norway shows the location of the study area (red) and other localities discussed in the text: 1, the Møre area that contains numerous localities (see Selvik, 1998 for all localities); 2, Ulvådalsvatnet (Sletten et al, 2003); 3, Vanndalsvatnet (Nesje et al, 2007); 4, Leirdalen (Matthews et al, 2009;5, Russvatnet (Støren et al, 2008;6, The Otta area (Sletten and Blikra, 2007); 7, Atnsjøen (Nesje et al, 2001a); 8, Butjønna (Bøe et al, 2006) YD marginal moraines are located at about 1000 m a.s.l. in Olden (Rye et al, 1997).…”

“…(A) Reconstructed centennial snow-avalanche activity in western Norway for the last 9000 years based on records from Møre in western Norway (Blikra and Selvik, 1998), around Vanndalsvatnet in Jostedalen, western Norway (Nesje et al, 2007), and around Oldevatnet in western Norway (this study). (B) Reconstructed number of debris-flows/century during the last 9000 years based on data from Leirdalen in Jotunheimen, southern Norway (Matthews et al, 2009), and from other areas in eastern and western Norway Sletten and Blikra, 2007;Sletten et al, 2003). (C) Reconstructed river floods during the last 9000 years in the catchments of the lakes Atnsjøen (Nesje et al, 2001a), Butjønna (Bøe et al, 2006) and Russvatnet (Støren et al, 2008).…”

“…An increasing number of Holocene mass-wasting and flood records are now becoming available from southern Norway (e.g. Blikra and Nesje, 1997;Blikra and Selvik, 1998;Bøe et al, 2006;Matthews et al, 2009;Nesje et al, 2001aNesje et al, , 2007Sletten and Blikra, 2007;Sletten et al, 2003;Støren et al, 2008). Lake sediments are considered to be one of the best high-resolution terrestrial archives of Holocene climate change in Scandinavia, and Norwegian proglacial lakes have been studied extensively to reconstruct past glacier variability and climate change (e.g.…”

“…An overview of hazardous events in southern Norway over the last 9000 years is given in Figure 11 by combining several records of snow-avalanches (Blikra and Selvik, 1998;Nesje et al, 2007; this study), debris-flows Matthews et al, 2009;Sletten and Blikra, 2007;Sletten et al, 2003) and floods (Bøe et al, 2006;Nesje et al, 2001a;Sletten et al, 2003;Støren et al, 2008) (Figure 11). Each record was first rescaled to a scale of 0-10 by multiplying the values with 10 and dividing by the maximum value of the record.…”