Characteristics and recent dynamics of thermo-erosional features in small catchments of Arctic Siberia

Thermal erosion is a prominent type of permafrost degradation that can lead to rapid changes in ice-rich permafrost landscapes. The process and its resulting landforms such as thermo-erosional gullies are reported to become increasingly active and widespread. (Re-)Activation of thermal erosion impacts the hydrological regime of affected landscapes and alters the biogeochemical composition of associated surface waters. Our study aims at assessing current rates and mechanisms of thermal erosion in small ice-rich permafrost catchments of Arctic Siberia. We investigated thermoerosional features in three different areas in and around the Lena River Delta that represent differing geomorphological, lithological and geocryological settings. We used a combination of field measurements, remote sensing methods including tacheometry, DGPS, and UAV surveys and subsequent GIS analyses to 1) quantify the morphometry of thermo-erosional landforms, 2) quantify the spatial extent of current thermo-erosional activity, and 3) quantify areal changes in activation and stabilization of thermal erosion over recent years to decades. Further data on snow depth and distribution in the gullies and valleys as well as hydrological and hydrochemical data of the associated streams aided the interpretation of observed spatial differences in thermal erosion rates and the development of active versus stabilized zones as well as their impacts on headwaters

Assessment of magnetic data for landfill characterization by means of a probabilistic approach

The sustainable vision of the Dynamic Landfill Management (DLM) deals not only with present but also with long-term waste management. In this context, DLM enhances the environmental assessment of landfills after closure as well as the recovery of materials and energy resources, for which, a proper characterization is required. To this end, geophysical methods have demonstrated their suitability for landfill exploration, characterization and monitoring. Due to the complexity of these sites and challenges in data acquisition and/or processing, the use of multiple methods is the best approach for landfill investigations. In this work, we used multiple geophysical methods, co-located with several trial pits and boreholes, to estimate the structure of a waste disposal site located in a quarry, and to better delineate the underlying geology composed of limestone. We applied electrical resistivity tomography (ERT), time-domain induced polarization (IP), H/V spectral ratio from microtremor records and magnetometry. We made a structural joint interpretation using the different datasets and the ground truth data. First, the ERT and IP data were individually inverted, and a first structural model was derived. Afterwards, we followed a parametric analysis of the H/V data to corroborate the thickness of some layers at the position of the seismic stations. Then, this model was used to compute synthetic magnetic data and by comparing them with the observed total field magnetic anomalies, a refined model was produced. We evaluated the improvement of including magnetic modelling by using a probabilistic approach previously reported. This approach is based on the computation of conditional probabilities by comparing the inverted models with the co-located data from trial pits and boreholes. Overall, we delineated the lateral and vertical extension of the waste body, the distribution of ash and lime deposits and estimated the upper limit structure of the bedrock

Assessing the risk of slope failure to highway infrastructure using automated time-lapse electrical resistivity tomography monitoring

Electrical resistivity tomography (ERT) monitoring provides time-lapse images of the subsurface. These images can be used to assess spatiotemporal variation in moisture content, which is a key driver of slope failure, making ERT monitoring an effective tool to evaluate precursory conditions of failure. This work presents the results of ERT monitoring on a slope above a major highway located on the border between England and Wales. During highway construction in the 1960s the slope was subject to several large landslide events which resulted in the re-design of the carriageway and installation of engineered mitigation measures. A section of the slope known as the ‘partially slipped area’ exhibited partial displacement during this time but did not progress to full slope failure, and therefore presents an ongoing risk to the highway, even though it does not experience ongoing displacement. An ERT monitoring system was installed across this area to monitor subsurface variations in moisture content. The results show a complex pattern of subsurface moisture dynamics within the partially slipped area when compared to the adjacent area of stable slope. This is most likely a result of the uneven and hummocky terrain in the partially slipped area and its effects on rainfall infiltration, storage and drainage, combined with the displacement-induced jointing present in the underlying sandstone units. The ERT results are used to assess the volume of unstable ground, placing the volume at the upper end of estimates from previous studies. Furthermore, analysis of the ERT dataset for surface displacements shows no movement at the site, which is confirmed by analysis of differential LiDAR plots and ground motion data derived from InSAR. This study demonstrates the application of ERT monitoring on a low activity, high risk slope, highlighting the need to understand subsurface processes at the slope-scale to inform long-term slope management

Imaging mass‐wasting sliding surfaces within complex glacial deposits along coastal cliffs using geophysics

This study presents a multidisciplinary survey combining geological fieldwork and geophysical data to better constrain the parameters influencing the morphology and behaviour of a retreating coastal cliff. Erosion rates are spatially highly variable and hard to predict because of the manifold parameters acting on them. Among these parameters, rock resistance exerts a paramount influence on cliff retreat. Characterizing the rock resistance distribution along a coastal region requires the mapping of several key subsurface properties including the bulk lithology, faulting, fracturing, or weathering. This is a difficult and expensive task because of the high spatial variability of these factors linked to the spatial complexity of the geology. Geophysical methods can be used to tackle this challenge by quickly providing the 3D visualization and distribution of these parameters within the subsurface. A fast-eroding portion of the Norfolk coast (UK) at West Runton is investigated using a multidisciplinary approach, combining ground-penetrating radar, electrical resistivity tomography (ERT), cone penetration tests, and outcrop studies. The results allowed us to build a 3D geological and geophysical model of a highly complex area of glacial geology. It forms part of a relict glaciotectonic thrust-tip moraine and sand basin sequence. The surfaces interpreted on radar data are associated with strong resistivity contrasts on the ERT data. These contrasts have been attributed to petrophysical variations between the lithological units. The base of the sand basin is marked by a low-permeability clay bed. Its low shear strength is likely to be more susceptible to failure, hereby accelerating the erosion rate of an already fast-eroding sand basin. The resulting model can be used as input for locally constraining the ground parameters in coastal recession and erosion models

Time domain reflectometry (TDR) potential for soil condition monitoring of geotechnical assets

The performance of geotechnical assets is influenced by various external factors including time and changing loading and environmental conditions. These changes could reduce the asset’s ability to maintain its function, potentially resulting in failure, which could be extremely disruptive and expensive to remediate; thus, the ability to monitor the long-term condition of the ground is clearly desirable as this could function as an early-warning system, permitting intervention prior to failure. This study demonstrates, for the first time, the potential of using time domain reflectometry (TDR) for long-term monitoring of the relative health of an asset (via water content and dry density) in a field trial where a clayey sandy silt was exposed to leaking water from a pipe. TDR sensors were able to provide detailed information on the variation in the soil conditions and detect abrupt changes that would relay a prompt for asset inspections or interventions. It is proposed that TDR could be used alone or together with other shallow geophysical techniques for long-term condition monitoring of critical geotechnical assets. Early-warning systems could be based on thresholds defined from the values or the relative change of the measured parameter

Die nahbare Bank

Diese Masterarbeit befasst sich mit der Frage, wie ein abstraktes Bankprodukt durch eine gesteigerte Erlebbarkeit verständlicher und attraktiver gemacht werden kann. Exemplarisch am Fondssparplan soll der Auftraggeberin, der Luzerner Kantonalbank AG, ein Weg aufgezeigt werden, wie eine Informationswebsite konzipiert werden kann, um komplexe und dadurch oftmals schwer fassbare Bankprodukte für die Gruppe der 25- bis 35-Jährigen erlebbarer, verständlicher und attraktiver zu machen. Die Auftraggeberin nimmt an, dass die Erlebbarkeit die Wahrnehmung und das Verständnis des Fondssparplans verbessert. Daraus ergeben sich folgende Forschungsfragen: Was heisst Erlebbarkeit im Kontext von abstrakten, gestaltlosen Bankprodukten? Wie lässt sich der Zugang zu gestaltlosen Produkten einer Bank am Beispiel des Fondssparplans erlebbar machen? Was sind die Erfolgskriterien, und wie lassen sich diese messen? Im Rahmen einer Research wird die Problemstellung aus einem weiten Blickwinkel beleuchtet. Dabei werden in einer Triangulation quantitative und qualitative Methoden miteinander kombiniert, um so eine möglichst belastbare, breit abgestützte Basis für die Lösungsfindung zu schaffen. Mit einem UX-Standard-Fragebogen wird der Begriff der Erlebbarkeit in diesem Projektkontext definiert und messbare Kriterien werden identifiziert, anhand derer der Ist-Zustand der Fondssparplan-Website der Luzerner Kantonalbank AG eingeschätzt wird. Für die Nutzermodellierung wird alternativ zur Persona die Methode der Mindsets angewandt. Die Lösungsansätze werden nach Lean UX, auf Hypothesen basierend, in fünf iterativen Zyklen bis zu einem testbaren Prototyp weiterentwickelt. Um eine strukturell sinnvolle Priorisierung der Feature-Hypothesen machen zu können, wird dabei das aufgabenorientierte Lean UX mit dem strukturorientierten 5S-Modell ergänzt. Die in der Research ermittelten Metriken dienen der Gegenüberstellung des entwickelten Lösungskonzeptes zur ursprünglichen Website und erlauben eine objektive, quantitative Erfolgsmessung in einem A/B-Test. Als Resultat liegt ein finaler Prototyp vor, der in einem quantitativen A/B-Test validiert wurde. Im Vergleich zur aktuellen Fondssparplan-Website zeigt die Lösung eine deutliche Verbesserung hinsichtlich der Erlebbarkeit. Die Ansätze, die exemplarisch für die Fondssparplan-Website entwickelt wurden, können im nächsten Schritt auf die Realisierbarkeit überprüft und auf weitere Websites angewandt werden, die zur Informationsvermittlung eines Bankproduktes dienen. Erkenntnisse, die aus der Research hervorgingen, jedoch von der Aufgabenstellung ausgeschlossen wurden, werden der Auftraggeberin als Anregung übergeben

Backpack LiDAR-based digital elevation models from the Perma-X expedition in West Alaska (2022)

During the Arctic Land Expedition Perma-X in West Alaska (2022-07-28 -- 2022-08-21), several LiDAR scans were acquired using a backpack laser scanning system (GreenValley LiBackpack DGC50). The surveys were carried out on the Baldwin Peninsula and on the Seward Peninsula. The goal of the campaign was to quantify permafrost landscape change by mapping various permafrost thaw features such as thaw slumps, gullies, and degraded ice wedge polygons. These features are predominantly less than 1 km2 in size. The 3D point cloud data from the LiDAR backpack were used to generate Digital Elevation Models (DEMs) of the thaw features. The point cloud processing workflow for these DEMs included point cloud georeferencing, filtering, and ground classification. In total, 15 DEMs were derived at different locations during this campaign. In addition to change detection, the accurate field data are suitable for model parameterization and validation from Earth observation data

Surface wave surveys for imaging ground property changes due to a leaking water pipe

This study demonstrates the use of Multi-channel Analysis of Surface Waves (MASW) to measure changes in Rayleigh wave velocity relating to both the initial trench construction and subsequent simulated failures (water leaks) of a buried water-pipe. The MASW field trials were undertaken in conjunction with a wider suite of geophysical monitoring techniques at a site in South-west England, within an area of clayey sandy SILT. The Rayleigh wave velocity through a soil approximately equals the Shear wave velocity, which in turn is predominantly dependant on the shear modulus of the soil (G) and this can be inferred to give a measure of the relative strength of a soil. It is proposed that the time-lapse measurement of Rayleigh wave velocity may be used to monitor ongoing changes in soil strength and therefore the MASW technique could perform a significant role in monitoring the initiation/progression of any internal processes within a geotechnical asset, before they would otherwise be identified through visual inspection alone