Séance de cours

Lentilles de glace: formation et impacts hydrologiques

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Dans cours

ENV-525: Physics and hydrology of snow

This course covers principles of snow physics, snow hydrology, snow-atmosphere interaction, and snow modeling. It transmits detailed understanding of physical processes within the snow and at its interfaces with the atmosphere and the ground, and presents ...

Description

Cette séance de cours traite de la formation des lentilles de glace, leur imperméabilité à l'écoulement de l'eau, et la redirection de l'écoulement de l'eau par les lentilles de glace. Il couvre également la double approche de Richards pour modéliser le transport de l'eau dans la neige, le rôle de la neige dans la modulation du ruissellement et le sort de la fonte des neiges. La séance de cours explore l'impact de la neige sur la formation des eaux de ruissellement, les termes de bilan énergétique dans les événements de pluie sur neige, l'excès de ruissellement de pluie prolongée et les chemins d'écoulement hydrologique de la fonte des neiges. En outre, il examine l'hydrographe de fonte des neiges, la transmission de l'eau liquide à travers la neige, la simulation de l'hydrographe d'écoulement des cours d'eau et l'interaction entre la fonte des neiges et le sol gelé.

Enseignant·e·s (3)

Wolf Hendrik Huwald

Dr. Hendrik Huwald is a scientist at the Laboratory of Cryospheric Sciences (CRYOS) and a lecturer at the Environmental Sciences and Engineering Section (SSIE) of the Swiss Federal Institute of Technology in Lausanne (EPFL). He completed his PhD in 2003 at the Swiss Federal Institute of Technology in Zürich (ETHZ), developing a numerical model for sea ice and studying energy transfer processes in the Arctic. Between 2005 and 2012 he was a post-doctoral fellow and scientist at the Laboratory of Environmental Fluid Mechanics and Hydrology (EFLUM) of EPFL working on Alpine snow-atmosphere interaction, and energy balance-related research mainly in mountain regions. During this time, he designed, led and participated in numerous large field experiments in different environments. In 2013 he joined the newly founded CRYOS laboratory where he conducted research in the domains of snow science, hydrology, boundary layer meteorology and environmental sensing. He has extensive experience with project management both on national and international level.

Johan Alexandre Philippe Gaume

I started my scientific career in 2008 at the Grenoble University in the IRSTEA laboratory where I did my master's thesis on the rheology of dense granular materials using the discrete element method. In the same lab, I followed with a PhD on the numerical modeling of the release depth of extreme avalanches using a combined mechanical-statistical approach and spatial extreme statistics. In 2013 I obtained a postdoc position at the WSL Institute for Snow and Avalanche Research SLF in Davos where I was in charge of developing and applying numerical models to improve the evaluation of avalanche release conditions and thus avalanche forecasting. While my PhD was mostly theoretical and numerical, my postdoc in Davos allowed me to gain a practical expertise by participating in laboratory and field experiments which helped to validate the models I develop. In 2016, I was awarded a SNF grant to work as a research and teaching associate in CRYOS at EPFL on the multiscale modeling of snow and avalanche processes. I developed discrete approaches to model snow micro-structure deformation and failure in order to evaluate constitutive snow models to be used at a larger scale in continuum models. I also developed numerical models for wind-driven snow transport. In 2017, I was a Visiting Scholar at UCLA to work on a Material Point Method (MPM) to simulate both the initiation and propagation of snow avalanches in a unified manner. The UCLA MPM model was initially developed for the Disney movie "Frozen" and has been modified and enriched based on Critical State Soil Mechanics to model the release and flow of slab avalanches. The results of this collaboration have been published in Nature Communications. In 2018, I was awarded the SNF Eccellenza Professorial Fellowship and became professor at EPFL and head of SLAB, the Snow and Avalanche Simulation Laboratory. At SLAB, we study micro-mechanical failure and fracture propagation of porous brittle solids, with applications in snow slab avalanche release. We also simulate avalanche dynamics and flow regime transitions over complex 3D terrain through the development of new models (depth-resolved and depth-averaged) based on MPM.In 2020, I obtained a SPARK grant to develop a new approach to simulate and better understand complex process chains in gravitational mass movements, including permafrost instabilities, rock, snow and ice avalanches and transitions to debris flows.

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Concepts associés (15)

Ice lens

Ice lenses are bodies of ice formed when moisture, diffused within soil or rock, accumulates in a localized zone. The ice initially accumulates within small collocated pores or pre-existing crack, and, as long as the conditions remain favorable, continues to collect in the ice layer or ice lens, wedging the soil or rock apart. Ice lenses grow parallel to the surface and several centimeters to several decimeters (inches to feet) deep in the soil or rock. Studies from 1990 have demonstrated that rock fracture by ice segregation (i.

Ice segregation

Ice segregation is the geological phenomenon produced by the formation of ice lenses, which induce erosion when moisture, diffused within soil or rock, accumulates in a localized zone. The ice initially accumulates within small collocated pores or pre-existing cracks, and, as long as the conditions remain favorable, continues to collect in the ice layer or ice lens, wedging the soil or rock apart. Ice lenses grow parallel to the surface and several centimeters to several decimeters (inches to feet) deep in the soil or rock.

Frost heaving

Frost heaving (or a frost heave) is an upwards swelling of soil during freezing conditions caused by an increasing presence of ice as it grows towards the surface, upwards from the depth in the soil where freezing temperatures have penetrated into the soil (the freezing front or freezing boundary). Ice growth requires a water supply that delivers water to the freezing front via capillary action in certain soils. The weight of overlying soil restrains vertical growth of the ice and can promote the formation of lens-shaped areas of ice within the soil.

Hydrologie

vignette|upright=1.5|Le cycle de l'eau Lhydrologie (du grec , « eau », et , « étude ») est la science qui s'intéresse à tous les aspects du cycle de l'eau, et en particulier aux échanges entre la mer, l'atmosphère (océanographie, climatologie...), la surface terrestre (limnologie) et le sous-sol (hydrogéologie), sur terre (ou potentiellement sur d'autre planètes). L'hydrologue contribue à la connaissance et gestion des ressources en eau et à leur durabilité en rapport avec les bassins versants environnementaux.

Cryoclastie

La cryoclastie (du grec ancien κρύος/kruos, « froid », et κλασις/klasis, « briser, rompre ») ou gélivation, ou gélifraction, est un processus géomorphologique de météorisation des roches, provoqué par les cycles de gel et de dégel de l'eau. En passant de la phase liquide à la phase solide, le volume de l'eau augmente d'environ 9 %. La glace contenue dans le réseau poreux des roches peut donc exercer des pressions disruptives importantes au sein de la masse rocheuse (de l'ordre de ).

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Séances de cours associées (10)

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Prévisions de neige et d'avalanche MOOC: Un avenir résilient : La science et la technologie au service de la réduction des risques de catastrophes

Discute de la prévision de la neige et des avalanches, de la simulation du couvert neigeux, de la prévision des ruissellements et de l'impact des changements climatiques.

Modélisation des Snowpacks : Physique et Applications

Explore la physique de la modélisation du manteau neigeux et ses applications pratiques dans les simulations de transport de vapeur et d'hydrologie.

Physique de la neige et hydrologie: Introduction

Couvre la physique et l'hydrologie de la neige, en soulignant son importance dans la modification des flux d'énergie et d'eau et son impact sur les ressources en eau douce.

Propriétés de la neige : distribution, variabilité et dynamique

Explore la distribution, la variabilité et la dynamique des propriétés de la neige, en soulignant l'importance de l'équivalent en eau de neige en hydrologie.

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Concepts associés (15)