Solifluction Movement Research Articles

Monitoring solifluction movement in space and time: A semi-automated high-resolution approach

Solifluction is the slow downslope movement of soil mass due to freeze-thaw processes. It is widespread on hillslopes in Polar and Alpine regions and contributes substantially to sediment transport. As solifluction lobe movement is in the order of millimeters to centimeters per year, it is difficult to measure with high spatial and temporal resolution and accuracy. In this study we developed a semi-automated approach to monitor movement using unmanned aerial vehicles, image co-alignment, and COSI-Corr (Co-registration of Optically Sensed Images and Correlation) to track slope movement from orthophotos. The method was applied on yearly images acquired between 2017 and 2021 of three solifluction lobes with different degrees of vegetation cover along an elevational gradient in Turtmann Valley, Swiss Alps. We found movement patterns across all three lobes with highest movement rates at the solifluction lobes center and lowest rates at lobe fronts. Overall, at the highest elevations (2560 m) lobe movement rates were highest with up to 14.0 cm yr−1 and intermediate elevations (2417 m) had the lowest values up to 2.9 cm yr−1. The lobe at the lowest elevation (2170 m) showed intermediate movement rates with up to 4.9 cm yr−1 for single years. Our monitoring approach provides yearly, spatially extensive movement estimates across the complete spatial extent of a lobe for each 1 cm2 of its surface, strongly increasing measurement resolution in comparison to traditional solifluction monitoring approaches using point measurements. In comparison to previous close-range remote sensing approaches, the use of a co-alignment procedure for the acquired drone data enabled a time-saving field setup without Ground Control Points (GCPs). The resulting high co-registration accuracy enabled us to detect solifluction movement if it exceeds 5 mm with sparse vegetation cover. Dense vegetation cover limited feature-tracking but detected movement rates and patterns are in the same order of magnitude and matched previous measurements using classical total station measurements at the lowest, mostly vegetated lobe. This study demonstrates the use of drone-based Digital Elevation Models (DEMs) and orthophotos in a semi-automated method which reaches the high spatiotemporal resolution necessary to detect subtle movements of solifluction lobes at yearly intervals at the sub-centimeter scale. This provides new insights into solifluction movement and how much it contributes to sediment transport. Therefore, our semi-automated approach has a great potential to uncover the fundamental processes and better understand solifluction movement.

Unmanned aerial vehicle‐based mapping of turf‐banked solifluction lobe movement and its relation to material, geomorphometric, thermal and vegetation properties

AbstractSolifluction is one of the most widespread periglacial processes with low annual movement rates in the range of —millimeters to centimeters. Traditional methods to assess solifluction movement usually have low spatial resolution, which hampers our understanding of spatial movement patterns and the factors controlling them. In this study, we (a) test the applicability of unmanned aerial vehicle (UAV)‐based structure‐from‐motion photogrammetry in comparison to a traditional total station survey to map surface movement of a turf‐banked solifluction lobe (TBL) in the Turtmann Valley (Switzerland). We then (b) relate the detected movement patterns to potential geomorphometric, material, thermal and vegetation controls, which we assessed using geomorphic and vegetation mapping, electrical resistivity surveys and temperature loggers. Our results show that (a) UAV‐based mapping can detect solifluction movement with high spatial resolution (one point per m2, total > 900 points) and rates and patterns consistent with a total station survey, but requires careful measurement set‐up and analysis; and (b) movement rates differ between lobe tread, riser and a ridge feature. Differences can be explained by heterogeneous material, geomorphometric, thermal and vegetation properties of the TBL, which promote different solifluction processes. Our study demonstrates the applicability of UAV‐based mapping in solifluction research and improves our understanding of solifluction processes and landform development.

Spatial Controls of Turf-Banked Solifluction Lobes and Their Role for Paraglacial Adjustment in Glacier Forelands

In glacier forelands, solifluction is a major and fast-responding paraglacial process in the adjustment of low- or moderately-inclined moraine slopes. However, the spatial pattern of the factors that control solifluction and their interactions are poorly understood. In this study, we combine geomorphic and vegetation mapping, analysis of borehole material and time domain reflectometry with two-dimensional (2D) and three-dimensional (3D) electrical resistivity tomography (ERT) to quantify the controlling factors and evaluate their influence on sediment transport. The investigated turf-banked solifluction lobe is located on the distal slope of a 1920s lateral moraine in the foreland of the Turtmann glacier in the southern Swiss Alps. Our data demonstrate the interaction between material, soil moisture and vegetation, which results in geomorphometric features such as (i) frontal and lateral risers, (ii) a lobe tread and (iii) a ridge. Lobe size indicates intense solifluction movement in the last 100 years. The interaction of controlling factors results in a negative feedback which stabilises the lobe and, thus, limits paraglacial sediment transport to frost heave processes on the ridge. Copyright © 2016 John Wiley & Sons, Ltd.

Local variations of solifluction activity and environment in the Abisko Mountains, Northern Sweden

ABSTRACTSeven sites within the mountain region of Abisko, northern Sweden, were selected for measurement of solifluction movement rates and correlation with the local environmental factors. Grids with sizes from 20 m × 30 m to 50 m × 100 m included both solifluction landforms and adjacent ground. Positions of movement markers and the terrain were recorded and the grid areas were digitally reconstructed. This allowed topography, vegetation and soil texture (fraction of fine material) surfaces to be interpolated and used together with data on soil moisture in statistical analyses. Significant correlations differ from site to site indicating that environmental factors have varying importance and inter‐relations depending on the local setting. Geomorphic work was also assessed within the grids. The results indicate measurable geomorphic work where no landforms are present. These areas may make larger contributions to sediment displacement than where solifluction landforms exist. Solifluction is an important denudational agent in the region and has its greatest impact on landscape development in the western part of the region. Copyright © 2011 John Wiley & Sons, Ltd.

The Role of Interannual Climate Variability in Controlling Solifluction Processes, Endalen, Svalbard

ABSTRACTA continuous record is presented of active layer processes at Endalen, Svalbard, over the period 2005–08. The monitored slope has a gradient of around 7° and in 2005, active layer depth was 94 cm, but this increased by around 14 cm over the next three years. The presence of an ice‐rich transient layer proved highly significant in determining the timing and profiles of solifluction movement. Frost heaving was 4.2 cm in 2005–06, 6.6 cm in 2006–07 and 3.2 cm in 2007–08, but thaw settlement exceeded frost heave in each year, giving a net total ground surface lowering of 6.2 cm. In winter, segregation ice was concentrated within the upper and lower active layer, leaving the central parts ice‐poor. During the summers of 2006 and 2008, thawing of the transient layer was associated with artesian pore pressures at 90 cm depth and basal soil shearing, but in 2007, when the thaw front failed to reach the ice rich basal zone, pore pressures during thaw were sub‐hydrostatic and no basal shearing was observed. Solifluction shear strain during thaw settlement resulted in downslope surface displacements of 2.3 cm in 2005–06, 1.2 cm in 2006–07 and 1 cm in 2007–08. Copyright © 2011 John Wiley & Sons, Ltd.

Spatial analysis of solifluction landforms and process rates in the Abisko Mountains, northern Sweden

AbstractThe occurrence of turf‐banked solifluction landforms in the Abisko region was analysed using a grid‐based approach and statistical modelling through logistic regression. Significant parameters in the model were the vegetation index NDVI, annual incoming potential radiation, wetness index, slope gradient and elevation. The model had an acceptable discrimination capacity and rather low model‐fit values, but clearly showed the importance of vegetation patterns for the occurrence of solifluction at a regional scale. Solifluction movement rates measured at eight sites were combined with model parameters and the annual duration of sun hours to regionalise solifluction movement rates through an unsupervised terrain classification. For comparison, the linear relationship between the probability of solifluction occurrence and variations in movement rates was also used to regionalise movement rates. Potential geomorphic work was calculated for six different areas within the region, with the greatest being for Kärkevagge, the area with the highest precipitation. The combination of a logistic regression model of mapped landforms and field measurements of solifluction rates represents a promising methodology to assess the occurrence and activity of the process at a regional scale. Copyright © 2010 John Wiley & Sons, Ltd.

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

.Solifluction movement rates from 1952 to 2008 for the Abisko region, northern Sweden, have been compiled and analysed through correlation tests and multiple regression. The temporal analysis is based on two datasets (Lobe11 & gridAB and Line B) from Kärkevagge. The dataset Lobe11 & gridAB show a strong correlation between movement rates and mean annual air temperature (MAAT) and MAAT is also identified as one of the significant contributing parameters in the multiple regression model. No significant correlations were found for the Line B dataset. The spatial analysis indicates generally higher movement rates in the western part of the region and at lower altitudes mainly between 700 and 900 m a.s.l., but the spatial variability is high. To reduce the influence of the temporal variation the data for the correlation tests of the spatial variations were divided into two parts: 1957 to 1980 and 1981 to 2008. The correlation analysis of the dataset 1957 to 1980 shows a significant negative correlation between annual average movement rates and permafrost probability and altitude. The dataset 1981 to 2008 shows a positive correlation between movement rates and wetness index. It is concluded that movement rates may increase with higher MAAT in the western part of the region (Kärkevagge), the spatial variability of movement rates within the region is very high and that altitude (and/or permafrost) together with wetness index are the main controls on the regional spatial variation. The study highlights the limitations in establishing statistical relationships between movement rates and climate using data from different field empirical studies.

Measurement of solifluction rates using multi‐temporal aerial photography

AbstractA 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. Copyright © 2009 John Wiley & Sons, Ltd.

Ice-wedge polygons and solifluction in the Adventdalen area, Spitsbergen, Svalbard

In the Adventdalen area, ice-wedge polygons are numerous from sea level up to altitudes of at least 500 m a.s.l. In higher areas, polygons are found in weathering material, mostly on bedrock Cretaceous in age or older. Many polygons are found on slopes inclined up to at least 25°. Polygonal patterns on slopes seem to be undisturbed by mass movement, indicating low rates of solifluction in the active layer. Polygons on slopes are discussed in relation to measurements of solifluction movement over a period of 14 years. Maximum solifluction rates are measured to 4.3 cm a year in a solifluction lobe. On smooth surfaces where solifluction lobes are absent, movement rates are much lower (Table 1). Polygons in higher parts of the terrain may be very old, since these areas most probably had permafrost during the whole postglacial time, as well as in earlier glacial periods with cold-based ice.

Survey of cryogenic processes, periglacial forms and permafrost conditions in South America

This geocryological inventory contributes to the state of the art and to recent advan.ces of Geocryology in the countries of South America with perrnafrost occurrence or seasonally frozen ground, where this field of research is of scientific interest. The aim is to increase the knowledge about the are as of the present cryosphere being modified by man and/or suffering changes due to climatic factors. A brief climatic analysis helps to understand the main South American cryogenic regions still poorly known and lacking the corresponding geomorphological cartography. The survey also emphasizes the fact that very few data are available on altitudinal Andean perrnafrost degradation caused by global warming processes, which should be monitored for hydrological and other reasons. The main cryogenic processes observed such as cryometeorization, nivation, solifluction, cryoturbation and sorting are described in different lithologies, places, etc. Some quantifications are given, such as data on solifluction movements and sedimentological methods applied to detect cryogenic phenomena. The latest data of Andean perrnafrost are summarized. They have recently been obtained with the help of different methodologies, including geophysics and/or, through borehole with ground temperature measurements. The most common Andean cryogenic forms are presented: microforms, patterned ground, felsenmeer, cryoturbation structures, thufurs in moors and solifluction lobes. Characteristic mesoforrns of the Central Andes, rock glaciers, or important elements of a periglacial environment such as sedimentary cryogenic slopes, cryoplanation surfaces or asymmetrical valleys are also described.

A Discussion on valley slopes and cliffs in southern England: morphology, mechanics and Quaternary history - The Quaternary history of the Lower Greensand escarpment and Weald Clay vale near Sevenoaks, Kent

In the neighbourhood, of Sevenoaks Weald many of the small hills and ridges standing up to 20 or 30 m above the streams in the clay vale south of the Lower Greensand escarpment are capped by Head deposits consisting of angular chert fragments, and other stones derived from the Greensand, set in a clay matrix. These deposits extend for a distance of at least 2 km from the escarpment, forming dissected remnants of what were originally extensive sheets, inclined at gradients of about 1.5°. The available evidence suggests they are periglacial solifluction deposits of Wol- stonian age. Probably at about the same period large-scale structural disturbances occurred in what are now spurs of the escarpment; massive blocks of the Hythe Beds subsided into the underlying Atherfield and Weald Clays, and the clays were forced up at the foot of the scarp in the form of bulges. Following this stage considerable erosion took place in the vale, accompanied by re­ treat of the escarpment within embayments between the spurs. On the eroded land­ scape solifluction debris moved up to 1 km from the scarp face during the Devensian period. This deposit again consists predominantly of clay with embedded angular chert fragments. It is about 2 m thick, with a minimum gradient of a little more than 2°, and overlies brecciated Weald Clay which typically contains several slip surfaces in its uppermost layers. Landslips in the escarpment within the embay­ ments probably occurred at about the same time. Not long afterwards, in the Late-Devensian Interstadial, around 12000 radiocarbon years b.p., a soil formed of which traces can be found buried beneath a lobate soli­ fluction sheet. The lobes extend over the lower sheet for distances of 300 m from the scarp foot at an average slope of about 7°. In the subsequent Postglacial period only minor changes have taken place; some escarpment landslips have been reactivated and the streams in the vale have eroded small channels or valleys not more than 4 m deep. Based on thaw-consolidation theory, and by using measured properties of the clays, calculations are presented which provide a reasonable explanation, in terms of soil mechanics principles, for solifluction movements of the active layer above perma­ frost on slopes inclined at angles as low as 1.5 or 2°. Under temperate conditions, mass movements are possible only on slopes steeper than about 8°. The paper includes an account of the longitudinal profiles and stratigraphy of the Eden and Medway river terraces.

Factors affecting the detection of slope instability with air photographs in an area near Sevenoaks, Kent

Summary Twenty-six sets of air photographs were used to test the best photographic conditions for detecting landslips, mainly old periglacial solifluction movement, along a ten mile stretch of sloping ground. A total of 141 old landslip features were detected and many varied in clarity on the different photographs, some being hard or impossible to detect on foot without the aid of air photographs. The repeated images of the same landslips on different sets of photographs produced a total of 2 715 photo-features for statistical studies. Analysis of the results showed that the best technical photographic conditions for detecting such features are the use of infra red colour film, stereoscopic photography with a short focal length lens, a nominal photographic scale of about 1:5 000, and a sun angle that casts local but not very extensive shadows. It is considered that automatic dodging can both enhance and suppress vital information on images, and that the best seasons for photography are likely to be spring and late summer to early autumn.

Solifluction on low-angled slopes in Northamptonshire

(Weeks 1969) has described a number of sites where slip surfaces have been encountered on slopes where the angle is less than the angle of ultimate stability against land sliding. The purpose of this note is to report two sites in Northamptonshire where slip surfaces have been observed on similarly low-angle slopes, and to suggest a possible mechanism for their formation. Reference to Fig. 1 shows that the two exposures are both at the 'feather edge' of cambered slopes of the Inferior Oolite (in this instance the Northampton Sand), overlying Upper Lias Clay. In both cases the Northampton Sand forms a structureless rubble, the junction with the Lias clay being about an inch above a slicken-sided slip surface of considerable extent. The slip surfaces are ascribed to solifluction movements. The first site (A in Fig. 1) , at Wellingborough [SP 903 693] was a temporary section in a cutting slope which exposed a slip surface that could be traced for nearly 150 ft parallel to its strike. The second site, (B), a road improvement scheme at Isham [SP 881 745], provided a section aligned obliquely to the direction of greatest slope. This section is shown in Fig. 2 . The down-slope extent of the Northampton Sand rubble was marked by a topographical feature where the slope increased from 4 to 6°, and where the slip surface ran out to ground level. In each case there is some evidence that the slip surface may be somewhat undulatory, though in general

The direct recording of solifluction movements

Describes strain gauge probes for direct recording of solifluction or similar small mass movements and briefly outlines their use in the measurement of vertical velocity profiles on a solifluction slope in the Dovrefjell area, central Norway.