10 research outputs found

    Geodetic monitoring of complex shaped infrastructures using Ground-Based InSAR

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    In the context of climate change, alternatives to fossil energies need to be used as much as possible to produce electricity. Hydroelectric power generation through the utilisation of dams stands out as an exemplar of highly effective methodologies in this endeavour. Various monitoring sensors can be installed with different characteristics w.r.t. spatial resolution, temporal resolution and accuracy to assess their safe usage. Among the array of techniques available, it is noteworthy that ground-based synthetic aperture radar (GB-SAR) has not yet been widely adopted for this purpose. Despite its remarkable equilibrium between the aforementioned attributes, its sensitivity to atmospheric disruptions, specific acquisition geometry, and the requisite for phase unwrapping collectively contribute to constraining its usage. Several processing strategies are developed in this thesis to capitalise on all the opportunities of GB-SAR systems, such as continuous, flexible and autonomous observation combined with high resolutions and accuracy. The first challenge that needs to be solved is to accurately localise and estimate the azimuth of the GB-SAR to improve the geocoding of the image in the subsequent step. A ray tracing algorithm and tomographic techniques are used to recover these external parameters of the sensors. The introduction of corner reflectors for validation purposes confirms a significant error reduction. However, for the subsequent geocoding, challenges persist in scenarios involving vertical structures due to foreshortening and layover, which notably compromise the geocoding quality of the observed points. These issues arise when multiple points at varying elevations are encapsulated within a singular resolution cell, posing difficulties in pinpointing the precise location of the scattering point responsible for signal return. To surmount these hurdles, a Bayesian approach grounded in intensity models is formulated, offering a tool to enhance the accuracy of the geocoding process. The validation is assessed on a dam in the black forest in Germany, characterised by a very specific structure. The second part of this thesis is focused on the feasibility of using GB-SAR systems for long-term geodetic monitoring of large structures. A first assessment is made by testing large temporal baselines between acquisitions for epoch-wise monitoring. Due to large displacements, the phase unwrapping can not recover all the information. An improvement is made by adapting the geometry of the signal processing with the principal component analysis. The main case study consists of several campaigns from different stations at Enguri Dam in Georgia. The consistency of the estimated displacement map is assessed by comparing it to a numerical model calibrated on the plumblines data. It exhibits a strong agreement between the two results and comforts the usage of GB-SAR for epoch-wise monitoring, as it can measure several thousand points on the dam. It also exhibits the possibility of detecting local anomalies in the numerical model. Finally, the instrument has been installed for continuous monitoring for over two years at Enguri Dam. An adequate flowchart is developed to eliminate the drift happening with classical interferometric algorithms to achieve the accuracy required for geodetic monitoring. The analysis of the obtained time series confirms a very plausible result with classical parametric models of dam deformations. Moreover, the results of this processing strategy are also confronted with the numerical model and demonstrate a high consistency. The final comforting result is the comparison of the GB-SAR time series with the output from four GNSS stations installed on the dam crest. The developed algorithms and methods increase the capabilities of the GB-SAR for dam monitoring in different configurations. It can be a valuable and precious supplement to other classical sensors for long-term geodetic observation purposes as well as short-term monitoring in cases of particular dam operations

    Iterative atmospheric phase screen compensation for near-real-time ground-based InSAR measurements over a mountainous slope

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    In this article, an atmospheric phase screen (APS) compensation algorithm for a near real-time ground-based interferometry synthetic aperture radar (GB-InSAR) over a mountainous area is investigated. A novel APS compensation scheme is proposed to compensate the fluctuated APS caused by a spatial 3-D inhomogeneous refractivity index distribution without any a priori knowledge of moving location. The proposed method simultaneously addresses to identify moving pixels by a criterion of absolute velocity estimated by the coherent pixels technique (CPT). The proposed method consists mainly of three steps: 1) the stratified APS compensation; 2) identification of moving pixel candidate; and 3) the residual APS [remained APS after 1)] compensation by Kriging interpolation. The steps mentioned above are iteratively applied in order to increase the accuracy of the whole process. In this framework, we develop the 2-D quadratic polynomial model of the refractivity index with respect to slant range and topographic height for modeling the stratified APS. Furthermore, a prediction of the residual APS is achieved by applying the intrinsic random function of order k (IRF-k) Kriging interpolation, taking into account the nonstationarity of the residual APS. We evaluate the proposed method using zero-baseline GB-differential InSAR (GB-DInSAR) data over a mountainous area located in Minami-Aso, Kumamoto, Japan, through the near real-time post-landslide measurement campaign

    Ground-based synthetic aperture radar (GBSAR) interferometry for deformation monitoring

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    Ph. D ThesisGround-based synthetic aperture radar (GBSAR), together with interferometry, represents a powerful tool for deformation monitoring. GBSAR has inherent flexibility, allowing data to be collected with adjustable temporal resolutions through either continuous or discontinuous mode. The goal of this research is to develop a framework to effectively utilise GBSAR for deformation monitoring in both modes, with the emphasis on accuracy, robustness, and real-time capability. To achieve this goal, advanced Interferometric SAR (InSAR) processing algorithms have been proposed to address existing issues in conventional interferometry for GBSAR deformation monitoring. The proposed interferometric algorithms include a new non-local method for the accurate estimation of coherence and interferometric phase, a new approach to selecting coherent pixels with the aim of maximising the density of selected pixels and optimizing the reliability of time series analysis, and a rigorous model for the correction of atmospheric and repositioning errors. On the basis of these algorithms, two complete interferometric processing chains have been developed: one for continuous and the other for discontinuous GBSAR deformation monitoring. The continuous chain is able to process infinite incoming images in real time and extract the evolution of surface movements through temporally coherent pixels. The discontinuous chain integrates additional automatic coregistration of images and correction of repositioning errors between different campaigns. Successful deformation monitoring applications have been completed, including three continuous (a dune, a bridge, and a coastal cliff) and one discontinuous (a hillside), which have demonstrated the feasibility and effectiveness of the presented algorithms and chains for high-accuracy GBSAR interferometric measurement. Significant deformation signals were detected from the three continuous applications and no deformation from the discontinuous. The achieved results are justified quantitatively via a defined precision indicator for the time series estimation and validated qualitatively via a priori knowledge of these observing sites.China Scholarship Council (CSC), Newcastle Universit

    REMOTE SENSING METHODS FOR THE INVESTIGATION OF THE EVOLUTION AND DYNAMICS OF ALPINE LANDSCAPES

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    Whilst the effects of present-day climate change are apparent in many environmental systems, much less is known about its impact upon the geomorphic systems characteristic of Alpine environments. This is an important knowledge gap because of the potential vulnerability of Alpine landscapes. The gap exists for two primary reasons: (1) observing climate forcing is challenging because it is manifest over timescales of decades to centuries, over which timescale geomorphic data are commonly scarce; and (2) the geomorphic response of landscapes to climate change can be complex, reflecting both spatially differential sensitivities to climate forcing and the effects of landscape heritage associated with historical glacial activity. Nonetheless, there is a consensus in the scientific community about the potentially high sensitivity of Alpine regions to climate change, because of the vulnerability of permafrost, glacial and nival processes to changes in atmospheric temperature and precipitation and the large amount of sediment stored on the associated hillsides. One approach to addressing this knowledge gap is to harness the power of remote sensing. A number of active and passive remote sensing methods could be employed for the reconstruction and monitoring of both whole landscapes and individual landforms. This Thesis aims to use such approaches to quantify the geomorphic dynamics of high mountain areas at the timescale of decades and so in the context of recent and rapid climate warming. It does so recognizing that both endogenous (landscape legacy) and exogenous (climatic forcing) processes may matter. To support this primary aim, a secondary aim arises: the evaluation of the potential of a number of remote sensing techniques for landscape and landform monitoring at multiple temporal and spatial scales. Thus this Thesis also tests in an Alpine setting the geomorphological potential of photogrammetric methods, using both aerial and hand-held sensors and both traditional and the innovative Structure-from-Motion processing approaches, and Terrestrial Laser Scanner techniques. The Thesis shows that remote sensing approaches prove to be an advantageous approach for a number of scales of application. In particular, over large spatial extents and in the case of decadal scale climate forcing of Alpine landscapes, photogrammetry was found to be capable of quantifying process rates within the limits of detection determined by the resolution of historical imagery. The information unlocked from aerial archives reveals distinct geomorphic responses to cold and warm periods and to changes in rates of precipitation and snow cover. Nonetheless, whilst enhanced sediment production is observed locally, evidence suggest a weak propagation of climate change signals through the landscape due to impeded connection to the river system and/or sediment transport capacity limitation. -- Bien que les effets des changements climatiques actuels soient visibles dans de nombreux systèmes environnementaux, un manque de connaissances des impacts sur les paysages alpins persiste. Cette lacune existe pour deux raisons principales : (1) l'observation du forçage climatique représente un défi, car ses conséquences se manifestent sur des périodes de plusieurs décennies, voire des siècles, pour lesquels les données géomorphologiques sont généralement rares ; et (2) la réaction du paysage aux changements climatiques peut être complexe, reflétant à la fois des sensibilités différentes au niveau spatial et les effets du patrimoine paysager, comme par exemple son histoire glaciaire. Néanmoins, il existe un consensus dans la communauté scientifique à propos de la haute sensibilité potentielle des régions alpines au changement climatique, en raison de la vulnérabilité du pergélisol et des processus glaciaires et neigeux aux changements de température atmosphérique et des précipitations et en raison de la grande quantité de sédiments stockés sur les versants alpins. Une stratégie pour aborder ces problématiques s'appuie sur le potentiel de la télédétection. Une série de méthodes de télédétection active et passive peuvent être utilisées pour reconstruire et surveiller le paysage entier et les éléments individuels qui le composent. Cette thèse vise l'application de ces approches pour quantifier les dynamiques géomorphologiques des paysages de haute montagne à l'échelle des décennies, et donc dans le contexte du réchauffement climatique récent et actuel. Cela est mis en pratique par la reconnaissance de l'importance des processus endogènes (héritage du paysage) et exogènes (forçage climatique). Le soutien à cet objectif en soulève un deuxième : l'évaluation du potentiel d'un certain nombre de techniques de télédétection pour le monitorage du relief et de ses formes géomorphologiques à plusieurs échelles temporelles et spatiales. Ainsi, cette thèse teste le potentiel des méthodes de photogrammétrie, en utilisant à la fois des senseurs aéroportés et portatifs et des approches de traitements traditionnels et innovants, et du balayage laser terrestre pour la recherche géomorphologique alpine. Les résultats obtenus montrent que les approches de télédétection se révèlent avantageuses pour des nombreuses échelles d'application. En particulier, sur de grandes étendues spatiales et dans le contexte du forçage climatique du paysage alpin, la photogrammétrie aérienne d'archive se montre appropriée pour la quantification des taux des processus dans les limites de détection déterminées par la résolution des photographies historiques. Les résultats démontrent l'existence d'une réponse géomorphologique distincte pour des périodes froides ou chaudes, ainsi que selon les variations des taux de précipitations et de couverture de neige. Néanmoins, alors qu'une production accrue de sédiments est observée localement, des évidences suggèrent une faible propagation des signaux du changement climatique à travers le paysage. Les raisons semblent être une faible contribution des versants au réseau fluvial et/ou une capacité de transport des sédiments limitée. -- Obwohl die Auswirkungen des aktuellen Klimawandels in zahlreichen Umweltsystemen beobachtet wurden, sind die Kenntnisse dieser Auswirkungen auf alpine Landschaften immer noch ungenügend. Diese Lücke existiert aus folgenden Gründen: (1) Das Beobachten klimatischer Auswirkungen auf alpine geomorphologische Prozesse stellt eine grosse Herausforderung dar, da diese sich über eine Zeitspanne von mehreren Jahrzehnten bis Jahrhunderten bemerkbar machen können, für die meist nur wenige geomorphologische Daten zur Verfügung stehen. (2) Durch die unterschiedlichen Empfind- lichkeiten verschiedener geomorphologischer Landschaftselemente sowie durch den grossen Einfluss des landschaftlichen Erbes, wie zum Beispiel der historischen Gletschertätigkeit, reagieren alpine Landschaftsentwicklungsprozesse sehr komplex auf Veränderungen des Klimas. Nichtsdestotrotz, auf- grund der hohen Empfindlichkeit des Permafrosts und der Gletscher- und Schneeprozesse gegenüber Veränderungen der atmosphärischen Temperatur und der Niederschlagsmenge sowie der grossen Menge an Sedimenten die an den Alpenhängen abgelagert werden und wurden, herrscht in der wis- senschaftlichen Gemeinschaft ein breiter Konsens über die potentielle hohe Sensibilität der alpinen geomorphologischen Systeme in Bezug auf den zu erwartenden Klimawandel. Fernerkundung bietet ein hohes Potential, um die geomorphologische Sensibilität zu erkunden. Aktive und passive Fernerkundungsmethoden können genutzt werden, um gesamte Landschaften sowie ihre einzelnen geomorphologischen Elemente historisch zu rekonstruieren und kontinuierlich zu überwachen. Die vorliegende Dissertation zielt auf die Anwendung dieser Ansätze, um die geomorpho- logische Dynamik der hochalpinen Landschaft über Jahrzehnte, und somit im Kontext der jüngsten Klimaerwärmung, zu quantifizieren. Der hier dargestellte Ansatz fokussiert vor allem auf die Bedeutung der endogenen (landschaftliches Erbe) und exogenen (klimatische Einflüsse) Prozesse. Die Umsetzung dieses primären Ziels zieht ein sekundäres Ziel mit sich: Die Bewertung des Potenzials einer Reihe von Fernerkundungsmethoden für das Monitoring von Landschaften und ihrer geomorphologischen For- men auf mehreren rüumlichen und zeitlichen Skalen. Damit wird das Potenzial photogrammetrischer Methoden, insbesondere luftgestützter und tragbarer Sensoren in Kombination mit traditionellen und innovativen "Structure-from-Motion" Ansätzen, sowohl auch terrestrischen Laserscanning Techniken für die alpine geomorphologische Forschung getestet. Die Ergebnisse zeigen, dass die hier dargestellten Fernerkundungsansätze für eine breite Reihe von Anwendungsskalen vorteilhaft sind. Die Archiv-Luftphotogrammmetrie ist besonders für die Quan- tifizierung der Auswirkungen des Klimawandels auf geomorphologische Prozesse in grossen Land- schaftsausschnitten geeignet. Die Auflösung der historischen Luftbilder bestimmt die Detektionsgrenze dieser Prozesse. Die aus den Luftarchiven ermittelten Informationen zeigen, dass kalte und warme Klimaphasen, sowie Variationen der Niederschlagsmenge und der Schneedeckenmächtigkeit unter- schiedliche Auswirkungen auf geomorphologische Prozesse haben. Obwohl ein lokaler Anstieg der Sedimentproduktion beobachtet werden konnte, konnten nur geringe Anzeichen einer Ausbreitung dieser Klimawandelsignale in der Landschaft beobachtet werden. Die Gründe hierfür scheinen der geringe Beitrag der untersuchten Berghänge zum Gesamtwasserabfluss und/oder die beschränkte Sedimenttransportfähigkeit zu sein. -- Nonostante gli effetti del cambiamento climatico attuale siano evidenti in molti sistemi ambientali, una conoscenza deficitaria perdura riguardo il suo impatto sui paesaggi alpini. Tale lacuna esiste per due principali ragioni: (1) gli effetti del cambiamento climatico sono difficili da osservare, in quanto manifesti su scale temporali di decenni, o persino secoli, per le quali prevale una scarsità di dati geomorfologici esaustivi; e (2) la reazione del paesaggio a tali cambiamenti può essere complessa e riflettere al contempo delle sensibilità spaziali differenti e gli effetti del patrimonio paesaggistico, come ad esempio la cronistoria glaciale. Tuttavia, vi è un consenso nella comunità scientifica riguardo l'ele- vata sensibilità delle regioni alpine ai cambiamenti climatici, a causa della vulnerabilità di permafrost e processi glaciali e nevosi ai cambiamenti di temperatura atmosferica e di precipitazioni, oltre che all'ampio stoccaggio di sedimenti concentrato sui pendii alpini. Una strategia per colmare questa lacuna di conoscenza può essere l'avvalersi del potenziale delle tecniche di telerilevamento. Vari metodi di telerilevamento attivo e passivo possono essere impiegati per ricostruire e monitorare il paesaggio ed i singoli elementi che lo compongono. Questa tesi si propone di utilizzare tali metodi per quantificare le dinamiche geomorfologiche nelle regioni di alta montagna a scala temporale decennale, e quindi nel contesto del riscaldamento climatico recente e attuale. In tale approccio viene riconosciuta l'importanza dei processi di tipo endogeno (di eredità paesaggistica) ed exogeno (climatici). A sostegno di questo obiettivo primario, una seconda finalità si pone: lo sviluppo e la valutazione di diverse tecniche di telerilevamento per il monitoraggio dei rilievi alpini e delle loro forme geomorfologiche, a più scale temporali e spaziali. Pertanto, questa tesi mette alla prova metodi di fotogrammetria, utilizzando al contempo sensori aeroportati e portatili ed approcci tradizionali ed innovativi (come l'emergente Structure-from-Motion), e tecniche di scansione laser per la ricerca geomorfologica in scenari alpini. I risultati ottenuti dimostrano come gli approcci di telerilevamento rappresentino una risorsa efficace e vantaggiosa per una vasta gamma di applicazioni. In particolare, ad ampia scala spaziale e nel contesto di cambiamento climatico nelle regioni alpine, la fotogrammetria aerea d'archivio si è dimostrata appropriata per la quantificazione dei processi geomorfologici entro limiti di rilevamento determinati dalla risoluzione delle immagini storiche stesse. I risultati rivelano una reazione geomorfica distinta a periodi di caldo e freddo, oltre che a variazioni di precipitazioni e copertura nevosa. Ciononostante, malgrado un accrescimento della produzione sedimentaria sia presente a scala locale, la propagazione dei segnali di cambiamento climatico attraverso il paesaggio appare debole. La ragione risiede nello scarso contributo dei versanti al sistema fluviale e/o a limitate capacità di trasporto di sedimenti

    From Regional Landslide Detection to Site-Specific Slope Deformation Monitoring and Modelling Based on Active Remote Sensors

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    Landslide processes can have direct and indirect consequences affecting human lives and activities. In order to improve landslide risk management procedures, this PhD thesis aims to investigate capabilities of active LiDAR and RaDAR sensors for landslides detection and characterization at regional scales, spatial risk assessment over large areas and slope instabilities monitoring and modelling at site-specific scales. At regional scales, we first demonstrated recent boat-based mobile LiDAR capabilities to model topography of the Normand coastal cliffs. By comparing annual acquisitions, we validated as well our approach to detect surface changes and thus map rock collapses, landslides and toe erosions affecting the shoreline at a county scale. Then, we applied a spaceborne InSAR approach to detect large slope instabilities in Argentina. Based on both phase and amplitude RaDAR signals, we extracted decisive information to detect, characterize and monitor two unknown extremely slow landslides, and to quantify water level variations of an involved close dam reservoir. Finally, advanced investigations on fragmental rockfall risk assessment were conducted along roads of the Val de Bagnes, by improving approaches of the Slope Angle Distribution and the FlowR software. Therefore, both rock-mass-failure susceptibilities and relative frequencies of block propagations were assessed and rockfall hazard and risk maps could be established at the valley scale. At slope-specific scales, in the Swiss Alps, we first integrated ground-based InSAR and terrestrial LiDAR acquisitions to map, monitor and model the Perraire rock slope deformation. By interpreting both methods individually and originally integrated as well, we therefore delimited the rockslide borders, computed volumes and highlighted non-uniform translational displacements along a wedge failure surface. Finally, we studied specific requirements and practical issues experimented on early warning systems of some of the most studied landslides worldwide. As a result, we highlighted valuable key recommendations to design new reliable systems; in addition, we also underlined conceptual issues that must be solved to improve current procedures. To sum up, the diversity of experimented situations brought an extensive experience that revealed the potential and limitations of both methods and highlighted as well the necessity of their complementary and integrated uses

    Terrestrial Radar Interferometric Measurement of Hillslope Deformation and Atmospheric Disturbances in the Illgraben Debris-Flow Catchment, Switzerland

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    We describe a method for rapid identification and precise quantification of slope deformation using a portable radar interferometer. A rockslide with creep-like behavior was identified in the rugged and inaccessible headwaters of the Illgraben debris-flow catchment, located in the Central Swiss Alps. The estimated volume of the moving rock mass was approximately 0.5 x 10(6) m(3) with a maximum daily (3-D) displacement rate of 3 mm. Fast scene acquisition in the order of 6 s/scene led to uniquely precise mapping of spatial and temporal variability of atmospheric phase delay. Observations led to a simple qualitative model for prediction of atmospheric disturbances using a simple model for solar radiation, which can be used for advanced campaign planning for short observation periods (hours to days)

    Influences of Snow Cover on Thermal and Mechanical Processes in steep Permafrost Rock Walls

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    Degradation of rock permafrost can cause instability due to influences on rock- and ice-mechanical properties. Permafrost conditions can be altered by thermal processes and, thus, also mechanical properties of rocks. Snow cover controls the seasonal occurrence of thermal processes. A conceptual approach is presented to explain snow cover influences on steep permafrost rock walls. This approach combines snow cover with thermal and mechanical processes. To support the conceptual approach, empirical data is presented to evaluate snow cover, the thermal and the mechanical regime. A combination of temperature data loggers, photos of automatic cameras and avalanche probe measurements allows the reconstruction of the temporal and spatial development of snow cover. Four snow stages can be distinguished and an overall cooling effect derived. In laboratory measurements, p-wave velocities of 22 different alpine rocks are tested and the influence of ice pressure on seismic velocities is evaluated. P-wave velocity increases dependent on lithology due to freezing and increase is dominated by an increase of the velocity of the rock matrix due to ice pressure. These findings are incorporated into a novel time-average equation and provide the basis for the applicability of refraction seismics in permafrost rock walls. The influence of snow cover on the thermal regime was investigated with the use of Seismic Refraction Tomography (SRT), Electrical Resistivity Tomography (ERT) and thermal modelling. Long lasting snow cover in 2013 delayed heat transport processes by insulating the underground and prevented active-layer thaw while snow cover absence resulted in deep thawing in 2012. Thus, snow cover plays a key role of permafrost evolution on slope facet scale. Snow cover is the main controlling factor of discontinuity movement and rock decay. The snow cover controls the occurrence of thermal expansion/contraction and volumetric expansion as it prevents these processes, while favouring ice segregation due to isolation. Volumetric expansion increases short-term cryostatic pressure, whereas ice segregation leads to seasonal cryostatic pressure. Active-layer thaw decreases shear strengths during summer and increases instability seasonally. The conceptual approach explains rock stability on seasonal and system scale. Therefore, this study delivers the basis in the understanding of stability of permafrost rock walls.Einflüsse der Schneedecke auf thermale und mechanische Prozesse in steilen Permafrost-Felswänden Die Degradation von Fels-Permafrost kann durch den Einfluss auf fels- und eismechanische Eigenschaften Felsinstabilität verursachen. Thermale Prozesse können die Permafrost-Bedingungen verändern und dadurch auch die mechanischen Eigenschaften von Felsen. Die Schneedecke kontrolliert das saisonale Auftreten dieser thermalen Prozesse. Ein konzeptioneller Ansatz wird vorgestellt, um den Einfluss der Schneedecke auf steile Permafrost-Felswände zu erklären. Dieser Ansatz kombiniert die Schneedecke mit thermalen sowie mechanischen Prozessen. Um den konzeptionellen Ansatz zu belegen, werden empirische Daten zur Schneebedeckung, zum thermalen und mechanischen Regime ausgewertet. Die Kombination von Temperaturdatenloggern, automatischen Kamerafotos sowie Lawinensonden-Messungen ermöglicht die Rekonstruktion der zeitlichen und räumlichen Schneedeckenentwicklung. Vier Schneephasen können unterschieden werden und ein überwiegend kühlender Effekt abgeleitet werden. In Labormessungen wurden P-Wellengeschwindigkeiten an 22 alpinen Felsproben getestet und der Einfluss des Eisdrucks auf seismische Geschwindigkeiten evaluiert. P-Wellengeschwindigkeiten steigen in Abhängigkeit der Lithologie durch Gefrieren und dieser Anstieg wird dominiert durch einen vom Eisdruck verursachten Anstieg der Felsmatrixgeschwindigkeit. Diee Erkenntnisse sind in eine neue Durchschnittszeit-Gleichung eingeflossen und stellen die Basis für die Anwendung der Refraktionsseismik in Permafrost-Felswänden dar. Der Einfluss der Schneedecke auf das thermale Regime wurde mit Hilfe von Refraktionsseismik-Tomographie (SRT), elektrischer Widerstandstomographie (ERT) und thermaler Modellierung untersucht. Die lang anhaltende Schneebedeckung in 2013 verzögerte Wärmetransportprozesse durch Isolierung des Untergrundes und verhinderte das Auftauen der Auftauschicht während die Abwesenheit der Schneedecke 2012 zu tiefgründigem Auftauen führte. Die Schneedecke spielt folglich eine Schlüsselrolle in der Entwicklung des Permafrostes auf der Hang-Fazies-Skale. Die Schneedecke ist der Hauptkontrollfaktor von Trennflächenbewegungen und Felszersatz und kontrolliert das Auftreten thermaler Expansion/Kontraktion sowie Volumenexpansion. Sie verhindert diese Prozesse, während die Eissegregation durch die Isolierungswirkung des Schnees begünstigt wird. Volumenexpansion führt zum kurzfristigen Anstieg kryostatischen Drucks, wohingegen die Eissegregation zu einem saisonalem kryostatischen Druckanstieg führt. Das Auftauen der Auftauschicht verringert die Scherfestigkeiten im Sommer und verursacht saisonal Instabilität. Der konzeptionelle Ansatz erklärt Felsstabilität auf saisonaler wie auch Systemskale. Diese Studie liefert damit die Grundlage zum Verständnis der Felsstabilität in Permafrost-Felswänden

    Monitoring and prediction in early warning systems for rapid mass movements

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    IEEE Geoscience and Remote Sensing Letters: Vol. 11, No. 2, February 2014

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    1. C-Band SAR Data for Mapping Crops Dominated by Surface or Volme Scattering / Giuseppe Satalino, et al. 2. A Novel Method for Parameter Estimation of Space Moving Targets / J. Tian, W. Cui, S. Wu 3. Operation of the Pedemis Sensor at the Aberdeen Proving Ground Standarized Test Site: single and multi-target inversions / Tomasz M. Grzegorczyk, Benjamin E. Barrowes 4. Improved Goldstein SAR Interferogram Filter Bassed on Empirical Mode Decomposition / Rui Song, et al. 5. Extraction of Boundaries of Rooftop Fence Buidings From Airborne Laser Scanning Data Using Rectangle Models / Suyoung Seo, Jeongho Lee, Yongil Kim 6. Using Polynomial Wigner-Ville Distribution for Velocity Estimation in Remote Toll Application / Stephane Meric, Rebecca Pancot 7. A Bayesian Detection Approach for Retrieval of Soil Moisture Variations Under Different Roughness Conditions / Claudia Notarnicola 8. Water Vapor Tomography With Two Microwave Radiometers / Sandra Steinke, et al. 8. Subspace Detection Using a Mutual Information Measure for Hyperspectral Image Classification / Md. Ali Hossain, Xiuping Jia Mark Pickering 9. Terrestrial Radar Interferometric Measurement of Hillslope Deformation and Atmospheric Disturbances in the Illgraben Debris-Flow Catchment, Switzerland / Rafael Caduff, et al. 10. An Adaptively Weighted Least Square Estimation Method of Channel Mismatches in Phase for Multichannel SAR System in Azimuth / Yan-yang Liu, et al. 11. A New Quality Map for 20D Phase Unwrapping Based on Gray Level Co-Occurrence Matrix / Gang Liu, et al. 12. Import Vector Machines for Quantitative Analysis of Hyperspectral Data / Stefan Suess, et al. 13. A Robust Image Fusion Method Based on Local Spectral and Spatial Correlation / Huixian Wang, et al. 14.Mapping High-Resolution Surface Shortwave Net Radiation From Landsat Data / Dongdong Wang, Shunlin Liang, Tao He 15.Semi-supervised Manifold Learning Based Multigraph Fusion for High-Resolution Remote Sensing Image Classification / Yasen Zhang, et al. 16. A Spatio-Temporal Pixel-Swapping Algorithm for Subpixel Land Cover Mapping / Yong Xu, Bo Huang 17. Data-Driven Compressive Sampling and Learning Sparse Coding for Hyperspectral Image Classification / Shuyuan Yang, et al. 18. A Novel Hierarchial Ship Classifier for COSMO-Sky Med SAR Data / Chao Wang, et al. 19.Spatial-Attraction-Based Markov Random Field Approach for Classiificationof High Spatial Resolution Multispectral Imagery / Hua Zhang, et al. 20. Four Component Scattering Power Decomposition of Remainder Coherency Matrices Constrained for Nonnegative Eigenvalues / Gaofeng Liu, et al. etc
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