This project investigates the size, timing and impact of African Humid Period (AHP) floods on upland landscapes along the Sahara Desert margins. Wobbling of the Earth’s axial spin alters atmospheric circulation patterns every ~20,000 yrs, repeatedly bringing wetter climates and flooding (~5,000 yr duration) to continental Africa (“Greening” of the Sahara). Investigations will analyse mountain fronts from different latitudinal and continentality contexts using Quaternary-Recent alluvial fans (cone-shaped sediment bodies formed on valley sides and mountain fronts). These landforms possess flood-related sedimentary and geomorphological records with significant but unrealised large spatial and long temporal potential to inform on climate change sensitive drylands; areas of early human occupation (archaeology) and modern population pressures (flood hazard). The PhD research will investigate key sites along the western Saharan Desert margin. Flood size quantification will involve measurement of flood sediments (boulder size) and geomorphology (slope and flood inundation area). This uses fieldwork and satellite analysis of palaeoflood and modern (for comparison / calibration) flood sites using hydrological modelling approaches (e.g. flood regime). The timing of flood events uses cosmogenic exposure dating techniques (i.e. 3He, 10Be, 26Al) applied to boulder surfaces deposited from different flood events. The impact of localised alluvial fan AHP flooding will utilise inter-site comparisons and comparisons with hydrological change datasets from other AHP archives (rivers, lakes, marine cores).
Plus d’informations :
[Website University of Plymouth]