Historical reconstruction of anthropogenic impacts on the hydrology of the Allier basin using spatially distributed hydrological modelling

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INRAE presentation

The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions.

Work environment, missions and activities

- You will be working in the RiverLy research unit (Lyon, France), which combines expertise in hydrology, hydraulics, environmental chemistry, ecology, ecotoxicology and microbiology to develop approaches at the various scales structuring hydrosystems and understand the quality, functioning and dynamics of hydrosystems. Its interdisciplinary research aims to take better account of natural and human-induced risks to improve the management and restoration of watercourses. The Catchment Hydrology team (HYBV) studies the functioning of catchments, water resources and associated risks (floods, droughts). Since 2011, the HYBV team has been involved in the development of the J2000 distributed hydrological model [1], which has already been used and implemented in several catchments across France (Arvan, Yzeron, Archèche, Ain, Saône, Rhône and Loire). This model allows for the simulation of key natural hydrological processes (interception by vegetation, rainfall/snow partitioning, surface runoff, soil infiltration, evapotranspiration, percolation to groundwater, and flow through the hydrographic network). It also represents water usage (dams, water withdrawals for drinking water, irrigation) to simulate water management scenarios.

- PhD thesis topic 

Water managers today face the impacts of climate change on water resource availability in their regions and must develop adaptation strategies to meet water demands amid increasing shortages while minimizing environmental impacts. The Explore2 project [2] has provided water stakeholders with possible hydrological trajectories throughout the 21^st century in France. However, these projections focus solely on the evolution of natural hydrology and must be complemented by joint changes and trajectories of direct anthropogenic actions in catchment areas that can incorporate adaptation strategies.

To enable water managers to implement such strategies, it is necessary to gain a better understanding of the long-term changes in anthropised catchments, and in particular the impacts of anthropogenic activities on catchment hydrology: abstraction, reservoir management, but also land use changes, which have been little studied. More specifically, this project focuses on the retrospective analysis of a catchment over an unprecedented time span (1871-2020) in order to quantify the hydrological response of the catchment to observed, progressive and cumulative anthropogenic influences over a time span similar to that of future projections.

This project will focus in particular on the Allier to Vieille-Brioude basin, where the changes in forest cover over 150 years are typical of the high level of reforestation in much of France [3]. This basin also has a number of important water uses in and downstream of the basin - hydroelectric and nuclear power generation on the Loire axis, irrigation of the Limagne plains, drinking water - all of which depend on the multiple-use management of the Naussac reservoir within the basin.

The research questions are: 

    - To what extent can the hydrology of a catchment be historically reconstructed under non-stationary climate and anthropogenic activity using distributed hydrological modelling?

   - How do the different anthropogenic influences affect the catchment’s hydrology? Can their relative contributions to flows and other components of the water balance be quantified?

   - What are the combined and/or cumulative impacts of human activities on the hydrology?

The first challenge, usually neglected in hydrological modelling, is to take into account the non-stationarity of land use in the Allier basin by using land use data from 3 different periods: The État Major map (1824-1866) georeferenced and vectorised by the National Institute of Geographic and Forest Information (IGN) [4], aerial photographs from the BDOrtho@Historique [5] (1945-1965) and Corine Landcover data [6] (1990 to 2020).

A second challenge will be to take into account the other types of anthropogenic impacts - water abstraction and storage/release in reservoirs - by using the various historical data available (data on water abstraction and/or consumption, data on agricultural practices, data on reservoir management, etc.) in order to reproduce as closely as possible the influenced flows observed in the catchment. A database necessary for the hydrological modelling of the 3 study periods has already been established. The work will consist of enriching this database with additional bibliographical research and translating the information collected - which varies in type, quantity and quality depending on the period - into parameters for the hydrological model.

A third challenge will be to quantify the contributions of each type of anthropogenic influence (climate, land use, abstraction, dam management) on the streamflows and other hydrological components of the Allier basin.

Such a hydrological reconstruction over a period of 150 years, taking into account both the physical evolution of a territory and its water management, has never been carried out before. In the longer term, the work carried out in this thesis will make it possible to extend the modelling method to other catchment areas in order to gain a better understanding of the hydrological response of catchments to water and soil management policies, and thus serve as a decision-making tool for the implementation of climate change adaptation strategies.

- Work programme:

• Bibliography and familiarisation with the modelling tools;
• Additional collection and processing of data on water use, dam management and land use, required to parameterise the hydrological model for the period 1871-2020;
• Implementation of the J2000 spatially distributed hydrological model for the Allier basin for 3 historical periods of 30 years, each considered to be stationary for land use and water uses: 1871-1900, 1941-1970 and 1991-2020;
• Calibration and evaluation of the hydrological model for the periods 1941-1970 and 1991-2020, for which observed flow data are available;
• Historical reconstruction: hydrological simulation for the earliest period (1871-1900), choice of indicators to be analysed and comparison of these indicators between the 3 simulated periods;
• Decomposition of anthropogenic contributions using a scenario-based approach (simulations of all possible combinations of anthropogenic influences observed historically) and analysis of the simulated hydrological responses.

The PhD thesis is funded 50 % by INRAE AQUA division [7] and 50 % by the BlueState (Conditions for State policies that better preserve water resources and ecosystems) project. BlueState is an interdisciplinary project – gathering political scientists, legal scientists, economists, agronomists, geographers, hydrologists, and ecologists - which main objective is to investigate how States govern freshwater access and use, and the main factors influencing the adoption or rejection of policies aimed at preserving water resources and ecosystems, while ensuring equity between stakeholders.

[1] F. Branger, Isabelle Gouttevin, François Tilmant, Thomas Cipriani, Christine Barachet, et al.. Modélisation hydrologique distribuée du Rhône. [Rapport de recherche] irstea. 2016, pp.116. https://hal.science/hal-02605058/

[2] https://www.inrae.fr/actualites/explore2-life-eauclimat-cles-ladaptation-gestion-leau

[3] Boyer, F. (2019) Le retour des forêts françaises, Confins; 39, https://doi.org/10.4000/confins.19070

[4] Lallemant, T., Touzet, T., & Gervaise, A. (2017). Une méthodologie nationale pour le géoréférencement et la vectorisation des cartes d’état-major, minutes au 1/40 000.

 Revue forestière française, 69(4), 341-352. https://dx.doi.org/10.4267/2042/67865

[5] https://geoservices.ign.fr/bdorthohisto

[6] Büttner, G., Kosztra, B., & Maucha, G. (2021). Copernicus land monitoring service, user manual. European Environment Agency, Copenhagen, Denmark. https://land. copernicus. eu/user-corner/technical-library/clcproduct-user-manual.

[7] https://www.inrae.fr/en/divisions/aqua

Training and skills

• Required training: Master's degree in hydrology
• Required knowledge and skills: water resources, catchment hydrology, modelling; proficiency in a programming language (e.g. R, Python, Matlab); geographical data analysis (e.g. QGIS); proficiency in written and spoken scientific English; A2/B1 level in French (for data collection in French documents or databases).
• Desired experiences : previous experience of developing and implementing hydrological models, spatially distributed if possible; previous experience of collecting and processing water use or management data (drinking water consumption, irrigation, dam management).
• Desired skills: organisation and autonomy in work; ability to work in a multi-disciplinary team; ability to summarise, write and communicate scientifically; motivation for environmental topics; motivation for research and analysis of historical data.

INRAE's life quality

By joining our teams, you benefit from (depending on the type of contract and its duration):

- up to 30 days of annual leave + 15 days "Reduction of Working Time" (for a full time);
- parenting support: CESU childcare, leisure services;
- skills development systems: training, career advise;
- social support: advice and listening, social assistance and loans;
- holiday and leisure services: holiday vouchers, accommodation at preferential rates;
- sports and cultural activities;
- collective catering.

- 75% reimbursement for transport to and from work

How to apply

I send my CV and my motivation letter