© 2017 by Clément Roques

AGU 2019 - Session H076 - Hydrogeological Controls on Groundwater Partitioning, Residence Times and Geochemical Fluxes in the Critical Zone

January 01, 2020

Please consider submitting an abstract to the session “H076 - Hydrogeological Controls on Groundwater Partitioning, Residence Times and Geochemical Fluxes in the Critical Zone” (description below), which will be held at the AGU Fall Meeting 9-13 December 2019 in San Francisco, CA.

Abstracts are due by Wednesday, 31 July at 23:59 EDT. Please use the abstract submission site. You can find more details at:  https://agu.confex.com/agu/fm19/prelim.cgi/Session/81493

Conveners:

Sarah Leray, Pontifical Catholic University of Chile
Clément Roques, ETH Swiss Federal Institute of Technology Zurich
Etienne Bresciani, Korea Institute of Science and Technology (KIST)
Pascal Goderniaux, Mons University

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Session ID: 81493
Session Title: Hydrogeological Controls on Groundwater Partitioning, Residence Times and Geochemical Fluxes in the Critical Zone
Section: Hydrology
 

Groundwater flow partitioning and residence times across a broad range of scales exert a critical control on groundwater and surface water quality as well as various geological processes. Previous studies on the subject have traditionally focused on topography-driven flows, assuming that the water table is a subdued replica of the topography. Comparatively, climatic, geologic, vegetative and anthropogenic controls on flow and transport have received little interest. Hence, although largely acknowledged, the role of these additional factors is still poorly understood.

This session explores recent advances and challenges in unravelling the role of all hydrogeological factors on groundwater flow partitioning and its implications for transport and geochemical fluxes. Presentations may cover a wide range of approaches including analytical and numerical modelling, hydraulic, chemical and geophysical data, and theoretical frameworks. The introduction and application of innovative characterization methods is encouraged. Contributions may focus on a variety of scales, from riverbeds to continents.

Youtube Channel of the 2018 Cargèse Summer School

July 09, 2019

We are happy to announce that videos of lectures, practical courses, pop-up and poster presentations that were given during the 4th Cargèse Summer School 2018 “Flow and Transport in Porous and Fractured Media” are now available online on our Youtube Channel!

Enjoy the videos and stay tuned for the next edition that will happen in 2021!

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September 08, 2017

Tracking active fractures in the valley-slopes of the Aletsch glacier

The phase III of the Aletsch project has just started with lots of exciting field campaigns during this summer! The main goal of this project is to investigate rock damage processes caused by pore pressure and temperature variations, and to understand instability mechanisms at the scale of the valley-slope in actual deglaciating environment. 

With Marc Hugentobler (PhD student) and Valentin Gischig, we were doing some logging and hydraulic tests in recently drilled boreholes. What a unique place for field work!! More information regarding the advancements of this project will be coming soon!

Some references:

- Grämiger, Lorenz (2017), Beyond debuttressing: Thermo-hydro-mechanical rock slope damage during glacial cycles. Doctoral thesis.​

- Grämiger, L.M., Moore, J.R., Gischig, V.S., Ivy-Ochs, S., Loew, S., 2017. Beyond debuttressing: Mechanics of paraglacial rock slope damage during repeat glacial cycles. J. Geophys. Res. Earth Surf. 122, 1004–1036. doi:10.1002/2016JF003967

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July 27, 2017

New article: Improved streamflow recession parameter estimation with attention to calculation of - dQ/dt

During the last 2 years, we have been working on streamflow recession analysis, mainly in the Oregon Cascades. We found a lot of different methods in the literature which are used to infer recession parameters based on the time rate of change in streamflow Q as a function of Q. The choice of one method above others was complicated as we could not find any overall comparison and presentation of their respective uncertainty. This paper compiles the results of our comparison exercise along with the description of the methodology we developed which appears to provide the most robust estimates.

A Matlab script will be available for download soon!

Abstract: The rate of streamflow recession can be used to assess storage-outflow properties of source aquifers. A common method of analyzing streamflow recession is to plot the time rate of change in streamflow Q as a function of Q in a log-log space. Theory predicts, for diagnostic recession regimes, a power law relationship -dQ/dt=aQ^b, where recession coefficients a and b are functions of the hydraulic and geometric properties of the aquifer and of boundary and initial conditions. Observational error reduces the accuracy of estimates of a and b with errors in estimating the time derivative of the late-time recession (-dQ/dt) being particularly sensitive to observational error. Here we propose a method to improve estimation of a and b with particular focus on the estimation of -dQ/dt. Compared to previously published methods we find greater robustness in estimates of -dQ/dt and recession parameters and less sensitivity to the methodological parameters employed. Previous methods result in up to 50 to 100% error when estimating the recession parameter b, while the proposed methodology produces errors below 5% in the cases analyzed.

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