Post-doctoral fellowship at HydroSciences Montpellier
UMR HydroSciences Montpellier (HSM), France (http://www.hydrosciences.org)
Integration of geophysical data for the improvement of flow models in
karst catchment.
Framework: ANR national project HydrokarstG2
The HSM Laboratory invites applications for a Post-Doc position in the field of flow modelling and
geophysical characterization of karst aquifer. In the framework of flow modelling in karst, hydrogeological
models are generally based on a transfer function representing the internal reservoir dynamics because
most of hydrological observations on karst systems are restricted to the water input (rain –
evapotranspiration) and output (spring discharge). Although such models efficiently describe the
input/output relation of the karst system, they can be viewed like black boxes (or grey-boxes) for which
internal variables have to be tuned to obtain an optimal behaviour. In this project we aim to map the
spatio-temporal water storage of the karst system for both short term (flood event) and midterm (seasonal
period).
The overall purpose of this position is i) to establish consistent links between geophysical data and karst
hydrodynamic in order to improve space-time 4D modelling of the water content; ii) to develop and improve
models allowing a better understanding of complex flow processes in karst systems, and iii) to perform and
analyze geophysical and geodetic data (MRS, gravity measurements, electrical sounding).
Flow modelling
An important requisite for integrated modelling is to account for near-surface hydrodynamic processes, in
particular the flow in the unsaturated zone. Research will particularly focus on the change of groundwater
resources over various hydrological cycles, and especially the distribution of groundwater between the
unsaturated and the saturated zone.
In a first step, flow in the karst system will be considered on the basis of reservoir based model [1] that
showed good ability at reproducing complex transfer in karst systems.
In a second step, geophysical measurements obtained from objective (iii) above will be incorporated into
the calibration and modelling process, as thus measurements can give consistent information about water
storage in karst [2,3]. The purpose is to better constrain the conceptual model as well as to increase the
predictive power of model internal variables [4]. This would allow the model to be used not only for
discharge modelling but also for groundwater resource analysis.
Geophysical characterization
The post-doctoral work aims to estimate the variations of the mass of water stored in the unsaturated zone
(epikarst and unsaturated zone) using jointly geophysical methods (Gravity, MRS, 3D seismic and
electrical/EM, borehole logging) in order to better understand the role and the dynamics of the different
compartments of the karst aquifer. The methodological approach for geophysical characterization of the
karst catchment will be as follow:
1.
MRS monitoring over different hydrological cycles, in order to estimate the change of the water
content beneath the local test zone at seasonal time scale and during rainfall events.
2.
3.
Combined interpretation of all acquired geophysical data (gravity, MRS seismic and electrical data).
Analysis of the groundwater circulation at smaller scale with borehole geophysical observations.
This work will need a close collaboration with the geophysicists (LTHE - EMMAH) and hydrogeologists (HSM)
involved in hydrogeological modelling of karst systems. Special attention will be paid to the analysis of the
consistency between geophysical results, and the capability of karst caverns and conduits and of limestone
matrix porosity to store water.
[1] Tritz S., Guinot V., Jourde H. (2010) Modelling the behaviour of a karst system catchment using non linear hysteretic conceptual
model, Journal of Hydrology, http://dx.doi.org/10.1016/j.jhydrol.2010.12.001
[2] Jacob T., Bayer R., Chery J., Jourde H., Le Moigne N., Boy J.P., Hinderer J., Luck B., Brunet P. (2008). Absolute Gravity monitoring of
water storage variation in a karst aquifer on the larzac plateau (Southern France), Journal of Hydrology, 359, 105– 117.
[3] Jacob T, Chery J, Bayer R, Le Moigne N, Boy JP, Vernant P, Boudin F. 2009. Time-lapse surface to depth gravity measurements on a
karst system reveal the dominant role of the epikarst as a water storage entity. Geophysical Journal International 177: 347–360.
[4] V Guinot, B Cappelaere, C Delenne, D Ruelland Objective function defintiion in conceptual hydrological modelling (2010) Proc.
SimHydro 2010 Conference, 2-4 June 2010, Sophia Antipolis Paper P12, 8 pp.
Candidate requirements:
A Ph.D. in hydrology, hydrogeology, geosciences, geophysics, is expected. The candidate will be able to
demonstrate good knowledge in geophysical prospecting and/or numerical modelling and significant
experience in one or more of these areas: hydrology, hydrogeology, geophysics and mathematical
modelling.
Application
Applicants are encouraged to submit an application package that includes a cover letter, curriculum vitae
and list of publications, PhD thesis abstract, and contact information of three professional references, to:
Dr. Hervé Jourde (herve.jourde@.um2.fr),
Pr. Vincent Guinot (vincent.guinot@.um2.fr),
Dr. Konstantinos Chalikakis (konstantinos.chalikakis@univ-avignon.fr,)
Dr. Anatoly Legchtenko (anatoly.legtchenko@ujf-grenoble.fr)
The starting date is negotiable, but 1st April 2011 would be ideal. The position is open until filled.
Duration: 12 months with possible extension of 3 months
Net monthly salary: ~2000 €
Localisation: Montpellier