PhD in geophysics and numerical modelling M/F

Job Description

Thesis Subject

From Structure to Function: Studying Subsurface Factors Influencing Catchment Hydrological Response
Context
Growing pressures on water resources — climate variability, contamination and overexploitation — highlight the need for a better understanding of hydrosystems, particularly their subsurface component. Despite a well-established conceptual framework, water storage, flows and interactions between groundwater and surface water remain poorly constrained, limiting the effectiveness of water management. These challenges are particularly important in mountainous catchments, where the subsurface plays a major role in sustaining streamflow during droughts and modulating flood responses. In contrast to climate and topography, the role of subsurface architecture and heterogeneity in controlling flow paths, water storage and streamflow recession remains poorly understood. This heterogeneity may in particular explain nonlinear behaviour, connectivity phenomena and hysteresis. The main questions are: (i) how does subsurface architecture control catchment response and low flows? (ii) How does it interact with topography? And (iii) how do internal states, particularly saturation, regulate flow partitioning and hysteresis?
Mission
This PhD thesis aims to investigate how subsurface architecture controls catchment response, flow partitioning and low-flow dynamics, by combining geophysical observations and process-based numerical modelling. Geophysical methods will be used to constrain the structure and properties of the subsurface, while numerical modelling will provide a framework for understanding the associated hydrological processes.
Activities
To achieve this objective, the PhD candidate will carry out the following activities:
· Develop alternative representations of subsurface architecture (soil, weathered rock, fractured and fresh bedrock) constrained by geophysical data from the study site.
· Assess the role of subsurface architecture in flow partitioning at the hillslope scale.
· Investigate the factors controlling streamflow recession and low-flow dynamics.
Expected Skills
The candidate should hold a Master's degree or equivalent qualification in geophysics. A strong interest in fieldwork and numerical modelling is expected, together with good proficiency in Python programming. The candidate should also demonstrate rigour, autonomy and an ability to work as part of a team in a collaborative environment. Excellent written and spoken English is required, as well as a strong interest in scientific communication and outreach to the general public.

Your Work Environment

The PhD will be carried out at the HydroSciences Montpellier Laboratory (HSM, UMR 5151 CNRS-Université de Montpellier-IRD), at the Hydropolis site, within the HYTAKE team. The fieldwork will be conducted on Mont Lozère, at one of the observatory sites of the OHMCV (Observatoire Hydrométérologique Méditerranéen Cévennes-Vivarais).
The PhD will be co-supervised by Patrick Lachassagne, Laboratory of HydroSciences Montpellier, University of Montpellier, Sarah Leray, Laboratory of HydroSciences Montpellier, University of Montpellier, and Rémi Valois, Inrae. It is part of the CNRS Junior Professor Chair (CPJ) of Sarah Leray, which aims to characterise and model water and energy transfers within the critical zone at different spatial and temporal scales in a Mediterranean context.
The PhD candidate will join the HYTAKE team and benefit from the scientific and instrumental environment of HSM, as well as the OZCAR network and the long-term monitoring infrastructure provided by the OHMCV
The PhD candidate will be enrolled in the GAIA Doctoral School.

Constraints and risks

The work will involve field campaigns, including the deployment and operation of geophysical equipment in outdoor environments and potentially mountainous terrain. Fieldwork may take place under variable weather conditions and may require physical activity such as walking over uneven or steep terrain and carrying equipment. Compliance with safety procedures and specific regulations will be required.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

The research professions