Missions

Formulation of an existing stochastic precipitation field generator, RAINSIM, in unsteady climate, for application to the estimation of hydrological inputs and extreme floods in future climate. Application to two basins with contrasting climates: the Ardèche at Sauze and the Isère at Grenoble.
The researcher will work as part of the IGE's HMCIS team, reporting directly to Juliette BLANCHET, and secondarily to Guillaume EVIN

Activités

Surface hydrology plays a crucial role in the supply of water and the production of energy by dams; everywhere it determines the frequency and intensity of droughts and floods. This is why it is important to quantify its future evolution as a result of climate change.

Studies on hydrological trends (e.g. Bisselink et al., 2020; Roudier et al.; 2016) are usually based on climate projections under different emission scenarios (RCP). Nevertheless, precipitation projections are known to be highly uncertain, even more so in France, which lies at the crossroads of different atmospheric influences (Blanchet et al. 2021).
An alternative approach to using precipitation and temperature projections for hydrological assessment is to carry out stochastic simulation under changing climatic conditions: for a given region, this means simulating realistic temperature and precipitation field series under the corresponding climate, using statistical modelling. This is the approach considered in the proposed research project. A daily stochastic rainfall generator in stationary climate, called RAINSIM, was developed as part of a previous collaboration between EDF and the IGE (Vaittinada Ayar et al., 2020). A generator of temperature fields associated with rainfall fields, which we will call TEMPSIM, will be developed in parallel to this postdoc by an independent recruitment.
Within the framework of the present postdoc, an unsteady climate formulation of the RAINSIM precipitation generator will be proposed, by linking part of its parameters to climate covariates (to be determined) projected by GCMs or GCM-RCM chains. The combined use of the non-stationary RAINSIM and TEMPSIM generators will therefore produce, over the modeling domain (typically a large hydrological domain of several thousand km²), several hundred daily series of rainfall and temperature fields over the desired simulation period (e.g. 2019-2099). These fields will be provided as input to the fully distributed hydrological model MORDOR-TS (Rouhier et al, 2017) to produce the corresponding flow series, which will be statistically analyzed for the estimation of hydrological inputs and extreme floods in future climate.

The proposed modeling will be applied to two basins with contrasting climates: the Ardèche at Sauze and the Isère at Grenoble in France.

The main scientific objectives of the project are as follows:
- Selection of suitable synoptic covariates to model past trends in intense and mean precipitation over the two study basins.
- Non-stationary formulation of Gamma marginal (i.e. local) precipitation distributions in RAINSIM with the introduction of one or more relevant covariates from climate modeling chains.
- Complete statistical qualification of the RAINSIM-TEMPSIM-MORDOR ensemble, both in terms of floods, mean inflows and low flows, in terms of current and future climate, and in terms of its ability to represent variability over recent decades in the two study basins.
- Participation in the writing of at least two scientific articles: one on non-stationary RAINSIM and its results in terms of the future evolution of extreme precipitation events in terms of frequency, intensity, spatial extent and duration; the other on the RAINSIM-TEMPSIM-MORDOR modeling chain and its results in terms of hydrological inputs and extreme floods in future climate

Compétences

- Expertise in climate and hydrology
- Descriptive statistics
- Good command of R software
- Teamwork
- Writing scientific articles in English and technical reports

Contexte de travail

The Institut des Géosciences de l'Environnement (IGE) is a public research laboratory under the auspices of CNRS, IRD, Université Grenoble Alpes (UGA) and Grenoble-INP, working on climate change and the anthropization of our planet in the polar, mountain and intertropical regions, which are particularly sensitive and have major societal implications.
The laboratory employs an average of 330 people, including 190 permanent members (researchers, teacher-researchers, engineers, technicians and administrative staff) and around 140 PhD students, post-docs and staff on fixed-term contracts. Each year, the laboratory welcomes around 120 interns and visiting scientists. The IGE is housed in four buildings on the Grenoble university campus (Glaciology building, OSUG-B, Maison Climat Planète and INRAE-Grenoble Saint Martin d'Hères).
The IGE is one of the main laboratories of the Observatoire des Sciences de l'Univers de Grenoble (OSUG), an INSU federative structure.

The IGE participates in the national strategy for research in the polar regions, in conjunction with national and international operators. It is a partner in numerous national and international projects.
The person recruited will work as part of the IGE's HMCIS team, reporting to Juliette BLANCHET and Guillaume EVIN.
Regular working sessions will also be scheduled with EDF hydrologists at EDF-DTG (an EDF engineering and expertise unit) in Saint-Martin-le-Vinoux

Contraintes et risques

Without.
The research will be carried out in either French or English, although it is expected that the non-French-speaking candidate will endeavour to learn the basics of French in order to facilitate communication and integration into the laboratory