Quantitative analysis of climate versus human impact on sediment yield since the Lateglacial: The Sarliève palaeolake catchment (France)

Abstract

International audienceMinimum rates of solid (SSY) and dissolved (DSY) sediment yield (SY) were evaluated in t/km 2 per yr from sediments stored in the Sarliève palaeolake (French Massif Central) for seven phases of the Lateglacial and Holocene up to the seventeenth century. The catchment (29 km2), mainly formed of limestones and marls, is located in an area rich in archaeological sites in the Massif Central. The respective impacts of human activities and climate on SY were compared by quantification of human settlements through archaeological survey and palynological data. During the Lateglacial and early Holocene up to about 7500 yr cal. BP, variations in SSY and DSY rates were mainly related to climate change with higher rates during colder periods (Younger Dryas and Preboreal) and lower rates during warmer periods (Bölling-Alleröd and Boreal). However, CF1 tephra fallout induced a sharp increase in SY during the Alleröd. During the middle and late Holocene after 7500 yr cal. BP, SSY and DSY greatly increased (by factors of 6.5 and 2.8, respectively), particularly during the Final Neolithic at about 5300 yr cal. BP when the climate became cooler and more humid. After this date, at least 75% of the SSY increase and more than 90% of the DSY increase resulted from human activities, but SSY rates showed little variation during Protohistoric and Historic Times up to the seventeenth century. SSY and DSY rates and DSY/SSY ratio indicate that catchment soils began to form during the Lateglacial and Preboreal, thickened considerably during the Boreal and Atlantic, finally thinning (rejuvenation) mainly as the result of human-induced erosion during the sub-Boreal and sub-Atlantic. Increased mechanical erosion during the late Holocene also induced an increase in chemical erosion

A 7000-year environmental history and soil erosion record inferred from the deep sediments of Lake Pavin (Massif Central, France)

“…Closer to Lake Pavin, a similar scenario, with the onset of a more humid climate at 5.3 cal kyr BP, has also been inferred from the sedimentological record of the Sarliève paleolake near Clermont-Ferrand ( Fig. 1A) (Fourmont et al, 2009, Macaire et al, 2010. This mid-Holocene transition is the result of the long-term orbital changes in seasonality, with a gradual decrease of summer insolation throughout the last 10,000 years (Berger and Loutre, 1991).…”

Increase in soil erosion after agricultural intensification: Evidence from a lowland basin in France

“…Lake and reservoir deposits have been widely used in contrasted topographic/climatic settings to investigate the link between human activity, soil erosion and sediment production, generally over long timescales (ranging between 10 2 and 10 3 yrs) (e.g. Macaire et al, 1997Macaire et al, , 2010Massa et al, 2012). In agricultural regions, most investigations were realized on downstream floodplain deposits, and few studies focused on sediment accumulation in upstream reservoirs/ponds.…”

6700 yr sedimentary record of climatic and anthropogenic signals in Lake Aydat (French Massif Central)

“…However, so far, only a few studies have been devoted to the interactions between the environment, humans and climate in this region, with the notable exception of its northern plain, the Limagne (e.g. Ballut, 2000;Fourmont et al, 2009;Macaire et al, 2010).…”