Lothar Schrott

Classic and new dating methods for assessing the temporal occurrence of mass movements

Abstract Establishing landslide chronologies is essential both for understanding causes of mass movements as part of fundamental geomorphological research, and for the assessment of landslide hazards as part of applied geomorphology. We discuss the applicability of different methods for determining landslide chronologies, frequencies and dynamics in relation to the type of material being dated, sampling location and type of mass movement. The emphasis is on the possibilities and limitations of the different dating methods. Established methods such as radiocarbon dating, lichenometry and dendrochronology are briefly discussed. The paper focuses, however, on (1) new analytical techniques like Accelerator Mass Spectrometry (AMS), Thermally Ionising Mass Spectrometry (TIMS) and laser fusion, which have led to significant improvements of established dating methods and on (2) new dating methods like Optically-Stimulated-Luminescence (OSL) dating and Alpha-Recoil-Track (ART) dating.

Spatial distribution of sediment storage types and quantification of valley fill deposits in an alpine basin, Reintal, Bavarian Alps, Germany

Spatial patterns of sediment storage types and associated volumes using a novel approach for quantifying valley fill deposits are presented for a small alpine catchment (17 km 2 ) in the Bavarian Alps. The different sediment storage types were analysed with respect to geomorphic coupling and sediment flux activity. The dominant landforms in the valley in terms of surface area were found to be talus slopes (sheets and cones) followed by rockfall deposits and alluvial fans and plains. More than two-thirds of the talus slopes are relict landforms, completely decoupled from the geomorphic system. Notable sediment transport is limited to avalanche tracks, debris flows, and along floodplains. Sediment volumes were calculated using a combination of polynomial functions of cross sections, seismic refraction, and GIS modelling. A total of, 66 seismic refraction profiles were carried out throughout the valley for a more precise determination of sediment thicknesses and to check the bedrock data generated from geomorphometric analysis. We calculated the overall sediment volume of the valley fill deposits to be 0.07 km 3 . This corresponds to a mean sediment thickness of 23.3 m. The seismic refraction data showed that large floodplains and sedimentation areas, which have been developed through damming effects from large rockfalls, are in general characterised by shallow sediment thicknesses (<20 m). By contrast, the thickness of several talus slopes is more than twice as much. For some locations (e.g., narrow sections of valley), the polynomial-generated cross sections resulted in overestimations of up to one order of magnitude; whereas in sections with a moderate valley shape, the modelled cross sections are in good accordance with the obtained seismic data. For the quantification of valley fill deposits, a combined application of bedrock data derived from polynomials and geophysical prospecting is highly recommended. D 2003 Elsevier B.V. All rights reserved.

The temporal stability and activity of landslides in Europe with respect to climatic change (TESLEC): main objectives and results

Abstract The major aim of the European project “The temporal stability and activity of landslides in Europe with respect to climatic change (TESLEC)” was to investigate the interrelationship between landslides, climate and time. The research was focused on three main objectives: (1) developing criteria for the recognition of landslides, (2) reconstructing past distributions of landslide incidents and their relationship to climatic change parameters, and (3) developing a hydrological and slope stability modelling framework using different test sites. The results of the project are related to these major objectives and include: (1) a technical manual for landslide recognition, (2) records of landslide activity, and (3) an evaluation of different hydrological and slope stability models. Landslide activity since 1950 has been generally high at all test sites. In some areas, there has almost been a continuous activity observed since the beginning of the monitoring. The records before 1950 are incomplete and probably indicate a lack of data rather than a lack of landslide activity. Whether the observed active landslides are carrying a climate signal cannot be stated for all test sites with high confidence, since some relationships between climate and landslides are uncertain. Thus, for the present, the complexity of the relationships between climate and landsliding seems to make it not feasible to establish “universal laws” all over Europe. On the other hand, it was possible to establish for some areas a cumulative rainfall-duration threshold for the reactivation of landslides. Future scenarios of regional precipitation were derived from downscaled general circulation model (GCM) experiments and used within simple slope hydrological and slope stability models. The evaluation of hydrological and slope stability models shows that physically based models are not always the best solution due to the model complexity and data requirements. For shallow landslides, more simple tank models are sometimes the better alternative. Future model development should strengthen considerations of fissure flow, sudden changes in permeability, larger landslide volumes and complex landslide topography.

DETECTION OF MOUNTAIN PERMAFROST BY COMBINING HIGH RESOLUTION SURFACE AND SUBSURFACE INFORMATION – AN EXAMPLE FROM THE GLATZBACH CATCHMENT, AUSTRIAN ALPS

Otto, J.‐C., Keuschnig, M., Götz, J., Marbach, M. and Schrott, L., 2012. Detection of mountain permafrost by combining high resolution surface and subsurface information – an example from the Glatzbach catchment, Austrian Alps. Geografiska Annaler: Series A, Physical Geography, 94, 43–57. doi:10.1111/j.1468‐0459.2012.00455.x Abstract Permafrost distribution in mid‐latitude mountains is strongly controlled by solar radiation, snow cover and surface characteristics like debris cover. With decreasing elevation these factors have to counterbalance local positive air temperatures in order to enable permafrost conditions. We combine high resolution surface data derived from terrestrial laser scanning with geophysical information on the underground conditions using ground penetrating radar and electrical resistivity tomography and ground surface temperature data in order to understand the effects of surface characteristics on permafrost distribution in an Alpine catchment, Austrian Alps (Glatzbach, 47°2′23.49″N; 12°42′33.24″E, 2700–2900 m a.s.l.). Ground ice and permafrost is found above an elevation of 2780 m a.s.l. on north‐east facing slopes in 2009, previous studies detected permafrost at the same site at 2740 m a.s.l. in 1991. Analysis of surface roughness as a proxy for grain size distribution reveals that the lower boundary of discontinuous and sporadic permafrost is lowered on rough surfaces compared to fine‐grain zones. At the same location modelled potential summer solar radiation in coarse grain zones is reduced by up to 40% compared to surfaces of fine grain sizes. The mostly patchy permafrost distribution at the Glatzbach can therefore be attributed to local surface cover characteristics, particularly regolith grain size and its influence on solar radiation. We conclude that the analysis of ground surface characteristics using very high resolution terrain data supports the assessment of permafrost in Alpine areas by identifying rough surface conditions favouring permafrost occurrence.

Spatial distribution of sediment storage types in two glacier landsystems (Pasterze & Obersulzbachkees, Hohe Tauern, Austria)

For the first time, geomorphological maps of the Obersulzbachkees (ca. 28 km2) and the Pasterze (ca. 39.7 km2) glacier landsystem at the catchment scale (1:10,000 and 1:12,500) are presented and the distribution of sediment storage types and (sub)recent sediment transfer processes are quantified and discussed. Special attention is drawn to the activity and function of sediment storages within the sediment cascade and on process (de)coupling of the sediment transfer systems. Glaciers cover ca. 50% of the landsystems and have retreated more than 1 km within the last six decades. The spatial distribution of sediment storage types delivers a record of the historical activity of the glaciers and the degree of sediment storage activity gives insights into the state of paraglacial landform adjustment. A typical landform assemblage is found in both landsystems. Moraine deposits are the dominant sediment storage type (coverage of ca. 3 km2 in both landsystems) and a significant source of (sub)recent sediment transfer. Deposits of reworked till account for ca. 4% of the total sediment coverage and paraglacial reworking is the main evolutionary factor for drift-mantled slopes with high activity in ice marginal and proximal locations (gully densities up to 3.7 per 100 metres of slope). With increasing distances from the glacier, the importance of paraglacial reworking decreases (gully density of 0.5 to 0.6). However, the contribution of paraglacial reworking to the overall sediment output is insignificant due to decoupling effects and till and debris are currently stored in both landsystems. The glacifluvial transport system is supply limited at the Obersulzbachkees and transport limited at the Pasterze. We consider the proglacial zone as a key control on sediment delivery from the glacier to the downstream fluvial system and hypothesize that the majority of sediment output from both landsystems is suspended load.

Geographic Information Science as a common cause for interdisciplinary research

Geographic Information Science (GIScience) seeks to understand the nature of geographic phenomena and geo-spatial information. It provides theoretical foundations for Geographic Information Systems (GIS) and the rationale for research and development in GIS and their applications. In this article, we analyse the role of GIScience as a common denominator among and between various disciplines, acting as a facilitator for interdisciplinary research. Starting from the development of a coordinated and structured doctoral programme,ten senior university faculty members from different disciplines examine the commonalities of spatial (Because of limited space we focus in this paper on the spatial domain and will only briefly reflect the spatio-temporal complexity) concepts in their respective fields in three interdisciplinary research clusters. Since the educational rationale was published recently, we focus on the role of GIScience in building an interdisciplinary and inter-departmental research alliance and conclude that the university-wide visibility has increased and opens new changes for another ‘spatial turn’.

Permafrost-Related Mass Movements: Implications from a Rock Slide at the Kitzsteinhorn, Austria

Rock instability in high mountain areas poses an important risk for man and infrastructure. At 3 p.m. on 18 August 2012 a rock slide event was documented at the Kitzsteinhorn, Austria. The release zone was detected on a north-exposed rock face below the cable car summit station (3.029 m). Analysis of terrestrial laser scanning (TLS) data delivered an accurate identification of the release zone yielding a rock fall volume of approximately 500 m3. Cubic Blocks with lengths of up to 4 m and block masses of up to 125 t were released during the event. The failure plane is located in a depth of approximately 3–4 m and runs parallel to the former rock surface (mean inclination 47°). Comparison with borehole data located less than 50 m from the release zone shows that failure plane depth is consistent with active layer depth. The event documentation is supplemented with observations of rock and air temperature, data on precipitation and snow depth, electrical resistivity tomography data, observed active layer depth and geological/geotechnical background data. The comprehensive ambient data suggests the influence of high temperatures and water availability for the triggering of the rock slide.

14.2 Fundamental Classic and Modern Field Techniques in Geomorphology: An Overview

Over the past three decades field techniques in geomorphology have evolved enormously. The advent of new technologies influenced even classic techniques such as mapping, because remote sensing, in combination with high-resolution digital elevation models, has significantly enhanced digital landform mapping and analysis. High-accuracy surveys of surface and subsurface structures using light detection and ranging (LiDAR), differential global positioning systems (DGPS), and geophysical techniques offer a wide range of challenges for geomorphological studies. Besides, field geophysics has become increasingly efficient to capture quantitative subsurface data and provides a better understanding of form–process relationships. This chapter introduces some classic and modern field techniques in a geomorphological context.

Glaciated valleys in Europe and western Asia.

In recent years, remote sensing, morphometric analysis, and other computational concepts and tools have invigorated the field of geomorphological mapping. Automated interpretation of digital terrain data based on impartial rules holds substantial promise for large dataset processing and objective landscape classification. However, the geomorphological realm presents tremendous complexity and challenges in the translation of qualitative descriptions into geomorphometric semantics. Here, the simple, conventional distinction of V-shaped fluvial and U-shaped glacial valleys was analyzed quantitatively using multi-scale curvature and a novel morphometric variable termed Difference of Minimum Curvature (DMC). We used this automated terrain analysis approach to produce a raster map at a scale of 1:6,000,000 showing the distribution of glaciated valleys across Europe and western Asia. The data set has a cell size of 3 arc seconds and consists of more than 40 billion grid cells. Glaciated U-shaped valleys commonly associated with erosion by warm-based glaciers are abundant in the alpine regions of mid Europe and western Asia but also occur at the margins of mountain ice sheets in Scandinavia. The high-level correspondence with field mapping and the fully transferable semantics validate this approach for automated analysis of yet unexplored terrain around the globe and qualify for potential applications on other planetary bodies like Mars.

Evaluating the effectiveness of hazard mapping as climate change adaptation for community planning in degrading permafrost terrain

Permafrost in northern Canada is susceptible to degradation due to rapid climate change, with hazard mapping promoted as an important activity to guide sustainable community adaptation and planning. This paper presents a framework for evaluating permafrost mapping exercises designed to inform climate change adaptation actions. We apply the framework using a case study of the Incorporating Climate Change into Land Development—Terrain Analysis project (ICCiLD). ICCiLD is a hazard mapping project utilizing interferometric synthetic aperture radar to monitor ground disturbance and categorize land development suitability in seven communities in the territory of Nunavut, Canada. We looked at one of the communities, Arviat, as our case study. We examined technical data and drew upon semi-structured interviews (n = 19) with map creators and users. We found ICCiLD added new and relevant information for community planning, increased awareness of the risks posed by permafrost thaw and built stakeholder relations. Strong coordination and high public consciousness of local climate impacts emerged as key factors underpinning project success. Nevertheless, in the case of Arviat, the effectiveness of the hazard maps in influencing land-use planning was constrained by communication challenges between project creators and end-users. These challenges included limited community access to the data and uncertainty surrounding how to operationalize the map suitability classifications. Broader climate change adaptation challenges included the presence of other more immediate community planning priorities and a limited ability to incorporate Indigenous ways of knowing into a technical mapping project. The lessons from this evaluation provide insight for the development of mapping-based adaptations across Arctic regions.