Description

The evolution of temperatures in lakes, rivers, and coastal areas remains difficult to predict despite the continuous improvement of observation and simulation methods for various sites. This prediction determines water quality management.
A major difficulty in predicting the temperature of water on the Earth's surface is the numerical simulation of thermal stratification using primitive equations. Reproducing daily variations in temperature and currents over a long period of time (several months) requires, on the one hand, sufficiently frequent observations (in time and space) of heat sources and sinks, but above all, stable and accurate numerical models, even if periodic readjustment of parameters is necessary.
The aim of the thesis is to analyze and resolve the difficulties involved in simulating the temperature of large bodies of water on the Earth's surface (lakes in particular), using mathematical analysis, numerical simulation, and potentially new physical experiments, in order to validate the proposed solution. To do this, we will begin by reviewing the observations and simulations already available at the LHSV for several French lakes. A particular indicator of success is the ability to simulate internal waves.
Beyond providing satisfactory temperature forecasts for lakes, the goal is to accurately predict various water quality indicators (e.g., dissolved oxygen concentration). This perspective will guide numerical modeling work, as well as the need to regularly recalibrate the model based on observations.

Skills required

Candidates for this thesis must have a solid background in computational fluid dynamics (analysis and implementation of algorithms at M2 level). Knowledge of environmental aquatics (hydrology, biogeochemistry) and/or fluid heat transfer would be an advantage.

Bibliography

Piccolroaz, S., Zhu, S., Ladwig, R., Carrea, L., Oliver, S., Piotrowski, A. P., et al. (2024). Lake water temperature modeling in an Era of climate change: Data sources, models, and future prospects. Reviews of Geophysics, 62, e2023RG000816. https://doi.org/10.1029/2023RG000816

Geddo, Z., Marquet, A., Guillot Legoff, A., Vinçon Leite, B., Boyaval, S., and Hong Le, M.: Three-dimensional thermo-hydrodynamic modeling of stratified inland waterbodies using Telemac3D, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18885, https://doi.org/10.5194/egusphere-egu25-18885, 2025

Dorostkar, A., Boegman, L., Schweitzer, S.A. et al. Three-dimensional numerical simulation of basin-scale internal waves in a long narrow lake. Environ Fluid Mech 23, 1167–1192 (2023). https://doi.org/10.1007/s10652-022-09868-z

Irani Rahaghi, A., Odermatt, D., and Naegeli, K.: Advancing Alpine lake monitoring and modelling through calibration, validation, and dissemination of high-resolution thermal remote sensing products, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18287, https://doi.org/10.5194/egusphere-egu25-18287, 2025.

Guillot-Le Goff, Arthur and Cartier, Yoann and Vinçon-Leite, Brigitte and Boyaval, Sebastien and Carmigniani, Rémi, Predicting microbiological contamination in urban rivers: an event-based indicator approach applied to the Seine River during the 2024 Paris Olympic and Paralympic Games. Available at SSRN: https://ssrn.com/abstract=5461777 or http://dx.doi.org/10.2139/ssrn.5461777

Chaojie Li, Émile Sylvestre, Xavier Fernandez-Cassi, Timothy R. Julian, Tamar Kohn,
Waterborne virus transport and the associated risks in a large lake, Water Research,
Volume 229, 2023, 119437, ISSN 0043-1354, https://doi.org/10.1016/j.watres.2022.119437.

Keywords

Thermo-hydraulics modeling , Numerical simulation, Lake water quality