50-year seasonal variability in East African droughts and floods recorded in central Afar lake sediments (Ethiopia) and their connections with the El Niño–Southern Oscillation

• DOI: 10.5194/cp-20-1837-2024
• Publication Date: 2024-08-15T09:56:24Z
• Authors: Carlo Mologni; Marie Revel; Eric Chaumillon; Emmanuel Malet; Thibault Coulombier; Pierre Sabatier; Pierre Brigode; Gwenael Hervé; Anne-Lise Develle; Laure Schenini; Medhi Messous; Gourguen Davtian; Alain Carré; Delphine Bosch; Natacha Volto; Clément Ménard; Lamya Khalidi; Fabien Arnaud
• Keywords: Teleconnection; Varve; Rift valley; East African Rift

Abstract. Understanding past and present hydrosystem feedbacks to global ocean–atmospheric interactions represents one of the main challenges preventing droughts, extreme events, related human catastrophes in face warming, especially arid semiarid environments. In eastern Africa, El Niño–Southern Oscillation (ENSO) was identified as primary drivers precipitation variability affecting water availability. However, northern East African Rift System (EARS) still suffers from underrepresentation predictive ENSO teleconnection models because scarcity local regional historical or palaeo-data. this paper, we provide a 50-year seasonal flood drought chronicle Awash River catchment study laminated sediment Gemeri Afambo lakes (central Afar region, Ethiopia) with aim reconstructing magnitude hydroclimatic events. Pluricentimetric micro-laminated lithogenic facies alternating plurimillimetric carbonate-enriched are investigated both lakes. We couple dating methods including radiocarbon, short-lived radionuclides, palaeomagnetic field variations, varve counting on lake deposits build high-resolution age model discuss hydrosedimentary dynamics over last ∼ 700 years focus 50 years. Using multiproxy approach, observe that following multicentennial enhanced hydrological period, two have experienced gradual decrease river load inflow since 1979 CE, attaining high evaporative conditions between 1991 1997 CE. 2014, construction dam increased agricultural management lower plain impacted erodibility soils balance basins, evidenced by disproportionate accumulation rate. Comparison our quantitative reconstruction (i) surface evolution, (ii) interannual flow rates, (iii) Niño 3.4 highlights intermittent connections sea temperature anomalies, EARS.