Measurement of solifluction rates using multi‐temporal aerial photography

Abstract

A new method is presented to assess decadal solifluction lobe movement and volumetric changes at the catchment scale. The method is based on photogrammetrical analysis of orthorectified repeat aerial photography in a geographic information system (GIS). High resolution aerial photographs from two valleys in northern Sweden, Kärkevagge and Låktatjåkka valleys, are used to quantify changes of the lobe fronts, as an indication of solifluction rates over a period of 41 years. Two methods are explored, the flow direction method and the front line method, in order to quantify the movement rates. Results show that the maximum combined root mean square error (RMSE) and resolution error amount to c. 1·7 m; no clear preference of one measurement method over the other was found. Application potential of the method is promising but reliability depends on the movement rates of the landforms and sufficient time span between the images. In the pilot study the measured yearly movement over the period 1959-2000 ranges from not-detectable to 63 mm/yr. Not-detectable means that movement cannot be detected within the resolution used in the study. Lobe advance rates are similar to measured surface movement rates and volumetric sediment flux by solifluction is found to be considerably lower than a previous estimate by Rapp (1960). Implications for lobe advance models are discussed. Photogrammetrical analysis is recommended as an important tool for detecting decadal solifluction movement at the catchment scale.

56 years of solifluction measurements in the abisko mountains, northern sweden – analysis of temporal and spatial variations of slow soil surface movement

“…The Låktatjåkka valley, oriented parallel to the Kärkevagge valley, has shorter slopes and a relatively flat east-facing slope. Solifluction landforms are generally smaller and less common in this valley, but at its southern upslope end classical lobe-shaped solifluction features are present (Ridefelt et al 2009 -2008). For location of the two weather stations, see Figure 2 are stone-banked lobes, non-sorted stripes and nonsorted sheets (Ridefelt et al unpublished data).…”

“…Regarding the validity of the movement rates, quantification by photo analysis for the period 1959 to 2000 of the total cumulative movement of a lobe, located at about a hundred metres from lobe 11, provides an independent assessment of lobe movement (Ridefelt et al 2009). The results are very similar in magnitude to those obtained by Rapp and Åkerman (1993) and Åkerman's (unpublished) lobe 11 during the period 1961 to 2002.…”

Syngenetic dynamic of permafrost of a polar desert solifluction lobe, Ward Hunt Island, Nunavut

“…Repeated freeze-thaw cycles trigger various types of mass movements on periglacial slopes, with solifluction being the most widespread slope-deforming process (Kinnard and Lewkowicz 2005;Ridefelt et al 2009). Although solifluction rates are generally limited to a few centimetres per year, they are, in the long term, the dominant mechanism of slope modification in periglacial environments (Åkerman 1996), thereby contributing greatly to the evolution of periglacial landscapes (Matsuoka 2001).…”

Late Holocene high precipitation events recorded in lake sediments and catchment geomorphology, Lake Vuoksjávrátje, NW Sweden

“…Ridefelt et al . () found that wetness together with altitude were the main controls on the spatial variation of solifluction within an area of uniform bedrock in northern Swedish Lapland. An increase in catchment wetness would thus increase solifluction and thereby generate more sediment deposition in the lake.…”