EGU23-3354, updated on 09 Jan 2024
https://doi.org/10.5194/egusphere-egu23-3354
EGU General Assembly 2023
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Tipping points in hydrology: attribution of regime shifts using historical climate simulations and dynamical system modeling

Erwan Le Roux1, Valentin Wendling2, Gérémy Panthou1, Paul-Alain Raynal3, Abdramane Ba4, Ibrahim Bouzou-Moussa5, Jean-Martial Cohard1, Jérome Demarty2, Fabrice Gangneron6, Manuela Grippa6, Basile Hector1, Pierre Hiernaux6, Laurent Kergoat6, Emmanuel Lawin7, Thierry Lebel1, Olivier Mora8, Eric Mougin6, Caroline Pierre4, Jean-Louis Rajot3, Christophe Peugeot2, and the TipHyc Project*
Erwan Le Roux et al.
  • 1Institut des Géosciences de l’Environnement (Univ. Grenoble Alpes, INRAE, CNRS, IRD, Grenoble INP), Grenoble, France
  • 2HydroSciences Montpellier (IRD, Univ. Montpellier, CNRS) Montpellier, France
  • 3Institut d’Ecologie et des Sciences de l’Environnement de Paris (CNRS, Sorbonne Univ., Univ Paris Est Creteil, IRD, INRAE, Univ. de Paris) Paris, France
  • 4Laboratoire d’Optique, de Spectroscopie et des Sciences Atmosphériques (Univ. des Sciences, des Techniques et des Technologies de Bamako) Bamako, Mali
  • 5Département de Géographie (Univ. Abdou-Moumouni) Niamey, Niger
  • 6Géosciences Environnement Toulouse (CNRS, IRD, UPS) Toulouse, France
  • 7Institut National de L’Eau, Cotonou, Benin
  • 8Délégation à l'Expertise scientifique collective, à la Prospective et aux Etudes (INRAE), Paris France
  • *A full list of authors appears at the end of the abstract
The Sahel (the semi-arid fringe south of the Sahara) experienced a severe drought in the 70s-90s. During this drought, an hydrological regime shift was observed for most watersheds in the Central Sahel: runoff has significantly increased despite the rainfall deficit. Did the drought cause this regime shift ? What if the drought did not happen ? To answer these questions, we introduce a simple dynamical model that represents feedbacks between soil, vegetation and runoff at the watershed scale and at the annual time step. This model is forced with annual rainfall and evaluated using long-term observations of runoff from selected watersheds. We find that the model forced with observed rainfall reproduces well the observed regime shift in runoff. For the attribution of the regime shift to the drought, we rely on two sets of historical rainfall simulations from CMIP6 global climate models: fully-coupled simulations that do not reproduce the drought, and atmosphere-only simulations (AMIP) that represent the drought. Our results show that a regime shift would have been unlikely without the drought. This approach will be extended to identify areas that are likely to experience an hydrological regime shift in the future.

TipHyc Project:

A. Ba, I. Bouzou-Moussa, J-M. Cohard, S. Conrad, J. Demarty, L. Descroix, J. Etchanchu, G. Favreau, S. Galle, F. Gangneron, A. Garcia-Mayor, M. Grippa, E. Guilman, B. Hector, P. Hiernaux, L. Kergoat, E. Lawin, E. Le Roux, T. Lebel, O. Mora, E. Mougin, G. Panthou, C. Peugeot, C. Pierre, J-L. Rajot, P-A. Raynal, N. Rouché, J-P. Vandervaere, T. Vischel, V. Wendling.

How to cite: Le Roux, E., Wendling, V., Panthou, G., Raynal, P.-A., Ba, A., Bouzou-Moussa, I., Cohard, J.-M., Demarty, J., Gangneron, F., Grippa, M., Hector, B., Hiernaux, P., Kergoat, L., Lawin, E., Lebel, T., Mora, O., Mougin, E., Pierre, C., Rajot, J.-L., and Peugeot, C. and the TipHyc Project: Tipping points in hydrology: attribution of regime shifts using historical climate simulations and dynamical system modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3354, https://doi.org/10.5194/egusphere-egu23-3354, 2023.