High-resolution fluvial record of late Holocene geomorphic change in northern Tunisia: climatic or human impact?

Abstract

In Northern Tunisia the late Holocene alluvial record of Medjerda floodplain sediments indicates geomorphic changes due to fluctuations of past climate, superimposed by the effects of human activity. Geomorphic activity occurred several times, interrupting stable conditions. Enhanced fluvial dynamics occurred around 4.7, 3.0, 1.7, 1.0 and 0.7 ka cal BP. A peak of activity took place about 0.4 ka cal BP. Some periods of fluvial activity show event-like phenomena, in particular when an anthropogenic impact intensifies climatic aridification. This has been the case around 1.7, 1.0, 0.7 and 0.4 ka cal BP with severe floods in the Medjerda valley. During Antiquity as well as around 1.3, 0.8 and 0.5 ka cal BP immature alluvial soils have developed, the first one being the most distinct. Late Holocene Medjerda alluvial history shows that fluvial dynamics in Northern Tunisia were predominantly climate-driven. Anthropogenic impact only intensified or weakened these processes.