PhD Studentship- Hydrological modeling and spatial altimetry for water resources

The National Center for Meteorological Research (CNRM) is a joint research unit (UMR 3589), of Météo-France and CNRS. The main goal of the research carried out at the CNRM is to improve weather forecasting and climate change, two of Météo-France's main missions. The CNRM is recognized as a major player in France and in the world in the fields of atmospheric science and the Earth's environment, which includes the topics of modeling the water cycle, monitoring the water resource, or the study of the impacts of climate change.

The PhD student will be hosted in the SURFACE team whose activities focus on the development and improvement of the modeling of ground-plant-atmosphere exchange processes for applications in numerical weather prediction at medium scale and in hydrology. The SURFACE team is particularly interested in the impact of climate variability and climate change on river flows and soil moisture. The objective is also to increase the realism of the models by a better interaction with the aquifers or the taking into account of the anthropic activities and their impact on the fluxes, as well as to prepare the future SWOT altimetric mission and to evaluate its contribution for a better understanding of the surface water balance and the hydrological processes.

Many recent studies have identified the evolution of water resources as a major issue in the coming century, particularly in the context of climate change and population pressure. However, the impacts of climate change and anthropization on water resources are still characterized by strong uncertainties. The study of the continental water cycle is mainly based on hydrological models, such as the ISBA-CTRIP model of the SURFEX platform developed at the CNRM. In addition, the future Surface Water and Ocean Topography (SWOT) space mission, scheduled for launch in 2021, will provide dynamic maps of continental water elevation across all rivers (width> 100m) and lakes (area> 250mx250m) of the globe for the first time. Owing to this new type of space-born observation and to the increase of computing capacities, it has now become possible to take into account and model anthropogenic factors, hitherto ignored in this type of model, such as irrigation and presence of dams, in the hydrographic network. The aim of the thesis is therefore to improve the river routing part of the ISBA-CTRIP model by integrating the effects of dams and reservoirs, and to investigate the potential contribution of SWOT data for the parameterization of the new high-resolution routing model.

As a first step, the PhD student will participate in the validation of the high resolution hydrographic network (1/12°) of the CTRIP model and adapt the SWOT data assimilation tools and methodologies developed in recent years. The second phase of the work will focus on the development of a dam-reservoir model that will represent the mass and energy balance in the reservoir, as well as the water release operations practiced by the resource managers. These operations may be based on a pre-established reservoir filling curve, or take into account various management activities such as hydro-electricity generation, low-flow maintenance or flood-peak reduction. In this second phase, the potential contribution of SWOT data will also be studied. In particular, the combination of height and water mask data from SWOT should allow the establishment of height-volume relationships, which are essential for reservoir mass balance computations. The study will initially be carried out over France, for which the CNRM already has hydrological expertise, and then it will be extended to other regions with contrasting hydro-climatic conditions. In particular, the Ebro Basin in Spain will be studied owing to significant anthropization and the availability of flow data and dam releases.