Project

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Advancing ground-penetrating radar data acquisition, processing, and analysis strategies for alpine glaciological applications

Applicant Irving James
Number 188575
Funding scheme Project funding (Div. I-III)
Research institution Institut des sciences de la Terre Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Geophysics
Start/End 01.09.2020 - 31.08.2024
Approved amount 548'078.00
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All Disciplines (2)

Discipline
Geophysics
Hydrology, Limnology, Glaciology

Keywords (14)

ground-penetrating radar; alpine glacier; 4D; ice deformation; drone; diffraction imaging; supersampling; multiple-point geostatistics; unmanned aerial vehicle; monitoring; time-lapse; 3D; subglacial hydrology; velocity analysis

Lay Summary (French)

Lead
Afin de comprendre l'impact du réchauffement climatique sur le paysage alpin, ainsi que sur la disponibilité, la saisonnalité, et la qualité de l'eau, on a besoin de modèles (i) de dynamique des glaciers alpins; (ii) d'érosion glaciaire et de transport des sédiments; et (iii) d’hydrologie sous-glaciaire. Tels modèles nécessitent de grandes quantités de données pour leur développement et leur utilisation, notamment en ce qui concerne les conditions à l'intérieur et à la base du glacier où une observation directe est impossible. Les méthodes géophysiques peuvent aider à répondre à ce besoin, car elles nous permettent de faire des images de l'intérieur de la Terre à partir des données acquises à la surface. En particulier, le géoradar (GPR) est devenu un outil précieux en glaciologie en raison de l'excellente propagation des ondes radar dans la glace et du potentiel d'imagerie à haute résolution.
Lay summary
La recherche proposée se concentrera sur le développement de nouvelles stratégies d'acquisition, de traitement, et d'analyse des données GPR pour fournir des informations nouvelles sur la structure interne, les propriétés, et la dynamique des glaciers alpins. Tout d'abord, nous profiterons des derniers développements technologiques pour créer un système GPR basé sur drone pour une acquisition rapide et sûre de données 3D et 4D (« time lapse »). Cela augmentera la vitesse actuelle du levé d'environ un ordre de grandeur, et il nous donnera la capacité de couvrir de nombreux hectares de la surface du glacier par jour. De nouvelles méthodologies de traitement seront ensuite développées pour ces données afin (i) d’identifier la distribution de chenaux sous-glaciaires et comment ils s’évoluent dans le temps; et (ii) d’estimer la déformation interne de la glace.
Direct link to Lay Summary Last update: 03.03.2020

Responsible applicant and co-applicants

Employees

Abstract

Glaciers worldwide are in a phase of rapid retreat that is unprecedented in modern times. In order to understand the impact of a warming climate on the mountain landscape, as well as on water availability, seasonality, and quality, conceptual and numerical models of alpine glacier dynamics, sediment transport and erosion, and englacial/subglacial hydrology are required. To this end, enormous progress has been made over the past few decades on the development of detailed numerical models of these phenomena. Such models, however, require vast amounts of data for their validation and use, most notably regarding conditions inside the glacier and at its base that are difficult to obtain because of limited direct access to these locations. Applied geophysical methods can help to fulfill this need, in the sense that they can provide spatially exhaustive information on subsurface heterogeneity and properties at a scale that is often relevant to modeling requirements. In particular, ground-penetrating radar (GPR) has become an invaluable tool in glaciological studies because of the excellent propagation of radar waves in snow and ice and its potential for high-resolution imaging. In the context of two PhD student projects at the University of Lausanne, the proposed research will focus on the development of novel 3D and 4D GPR data acquisition, processing, and analysis strategies with the aim of providing new and important information on the internal structure, properties, and dynamics of alpine glaciers. In the first project, which is primarily theory and computation based, we will advance the use of 3D GPR for identifying englacial and subglacial channels and voids through the development of diffraction separation, velocity analysis, and imaging procedures. Here, we will take advantage of cutting-edge research from the field of exploration seismology, where diffraction velocity analysis and imaging have become topics of significant interest. Close collaboration with a leading seismic exploration research group in the U.S. will allow for testing and adaptation of the most recent developments in this domain. In the second part of this PhD project, we will explore the use of multiple-point-geostatistics (MPS) simulations to supersample 3D GPR in order to obtain an even and dense distribution of traces across the glacier surface. Typically, 3D GPR data are limited by the fact that the along-line measurement spacing is much greater across-line one, which can greatly hinder and bias the visualization, analysis, and interpretation of these data. Trace supersampling using MPS methods, as opposed to classical interpolation, is expected to provide an effective means of resolving this issue.In the second PhD project, which is heavily field based, we will develop a lightweight, real-time-sampling, drone-based GPR system for the rapid and safe acquisition of high-resolution 3D and 4D data on alpine glaciers. Typical ground-based glacier GPR surveying using standard systems based on sequential sampling is notoriously slow, especially in 3D when a dense spacing of parallel 2D GPR lines must be acquired. Further, the work is highly fatiguing and dangers such as crevasses and moulins must be constantly avoided. Development of a drone-based system will allow for a roughly order-of-magnitude increase in GPR survey speed with the capacity to cover many hectares of the glacier surface per day. Flying will be done 1-2 m above the ground, following the local topography, and with a dense (~1-m) line spacing in order to provide detailed information on internal glacier structure, properties, and dynamics. The system will be used to acquire 3D and 4D data at two well-studied field sites in the Swiss Alps for the purpose of (i) identifying the pattern of subglacial channels and voids and how they evolve over time; and (ii) estimating the internal deformation of the ice.
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