Drainage network expansion of the Salagou drainage basin (S. France): an example of relief response to recent climate change?

Continental erosion is known to be strongly controlled by climate but the way by which geomorphological systems respond to climate change still remains poorly understood. Recent numerical modelling suggests that drainage networks are subjected to strong spatial fluctuations but few studies of natural systems have addressed this phenomenon because of the difficulty of documenting the evolution of erosional landscapes. A detailed field analysis has allowed reconstruction of the past topography of a drainage basin located in southern France where remnants of a past landscape are well preserved. A change from a smooth to a present-day dissected landscape is observed and related to a change in the dominant processes of erosion. This evolution is interpreted in terms of fluctuations in drainage network extent in response to a Holocene increase in precipitation.