EGU21-4634, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-4634
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Hydro-climatic fluctuations and their impact on Lake Abhe environments (Ethiopia & Djibouti): a lesson from the past 10,000 years

Carlo Mologni1,2, Laurent Bruxelles3,4, Fabien Arnaud5, Pierre Sabatier5, Anne-Lise Develle5, Emmanuel Malet5, Eric Chaumillon6, Mathieu Schuster7, Gourguen Davtian2, Jessie Cauliez3, Marie Revel1, and Lamya Khalidi2
Carlo Mologni et al.
  • 1Université Cote d'Azur, CNRS, Observatoire de la Côte d'Azur, IRD, Géoazur, France (mologni@geoazur.unice.fr)
  • 2Univ. Côte d’Azur, CNRS, CEPAM – UMR 7264, 24 av. des Diables Bleus 06357 Nice, France
  • 3Univ. Toulouse Jean Jaurès, TRACES - UMR5608, CNRS, 5 allées Antonio Machado 31058 Toulouse, France
  • 4Institut Français d’Afrique du Sud, Johannesburg, South Africa
  • 5Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, EDYTEM, 73000 Chambéry, France
  • 6LIENSs (CNRS - La Rochelle Université) - UMR7266, 2 rue Olympe de Gouges, 17000 La Rochelle, France
  • 7CNRS, Université de Strasbourg, UMR 7063, Institut Terre et Environnement de Strasbourg

Throughout the last 14 ka, tropical Africa experienced significant hydrological changes that were mainly driven by the orbital precession cycle, which controls the intensity of the African monsoon. Recent studies conducted in lake and deltaic sedimentary records suggest that long-term monsoon humid oscillations (African Humid Period / AHP ~14 – ~6 ka) were punctuated by centennial-scale episodes of hyperaridity. However, the abrupt or gradual aridification modalities since the end of the AHP and the modalities of the centennial-scale episodes, as well as their impacts on past and current environments are still debated.

The Lake Abhe basin in the Central Afar region (Ethiopia & Djibouti) is the endorheic receptacle of freshwater originating in the Ethiopian Highlands, and represents a hydro-sedimentary system sensitive to hydro-climatic changes in East Africa. Today it is characterized by residual lakes (Gamari and Afambo lakes) and a hyper-arid climate, while during the AHP, the Abhe basin was occupied by a Mega-lake and by humid environmental conditions. Holocene climatic disruptions drastically changed the landscapes and ways of life along this basin.  

The aim of this study is to describe, interpret and estimate the impact of hydro-climatic oscillations on the evolution of Lake Abhe’s littoral lacustrine environments and palaeolandscapes since the AHP from different viewpoints.

Indeed, this research combines paleoclimatological and geomorphological studies based on a new set of 14C ages on two lacustrine cores and on several morpho-sedimentary outcrops spanning the Early to Late Holocene. Our results allow us to: a) refine the temporal occurrence and the hydrological modalities of the AHP including short-term arid episodes linked to Younger Dryas and 8.2 ka North Atlantic events; b) recognise some paleo-shoreline geomorphic features linked to lake level fluctuations, as well as the development littoral pedological horizons and the activation/shutdown of the perilacustrine fluvial network during humid and arid events; c) track these changes until the present day, and discuss their evolution scenario in the near future.

Comparing with other regional climatic records, we show how Lake Abhe basin was highly reactive to East African monsoonal regimes, and how current hydrological changes could impact its environments.      

How to cite: Mologni, C., Bruxelles, L., Arnaud, F., Sabatier, P., Develle, A.-L., Malet, E., Chaumillon, E., Schuster, M., Davtian, G., Cauliez, J., Revel, M., and Khalidi, L.: Hydro-climatic fluctuations and their impact on Lake Abhe environments (Ethiopia & Djibouti): a lesson from the past 10,000 years, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4634, https://doi.org/10.5194/egusphere-egu21-4634, 2021.

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