Palaeohydrological changes recorded from a small Moroccan Middle Atlas pond during the last 6000 cal. yr BP: a multi-proxy study
Résumé
Study of the hydro-sedimentary dynamics of lakes provides key information on hydrological changes. In this work, we investigate Lake Azigza in the Moroccan Middle-Atlas, a region that suffers from a scarcity of observational hydrological data necessary for a coherent management of water resources. Sedimentary deposits of Lake Azigza (32°58'N, 5°26'W, 1,550 metres a.s.l.) were dated and analyzed by combining geochemical and mineralogical measurements coupled with microfacies characterization for the last 134 years. The detrital component derived from XRF-elemental composition and the microstructures observations of the lake sediments provided proxies of runoff activity and lake-level changes respectively. These proxies were calibrated with regional hydro-climatic and instrumental measurements available over the last 50 years and used to reconstruct past hydrological changes on interannual to decadal timescales between 1879 and 2013. Since 1879, lake level and runoff proxies responded in phase to regional inter-annual precipitation variations. We also show that after the major lake-level drop observed in 2008, the response of the runoff proxy to variable precipitation regime is enhanced. Such an approach emphasizes the potential of these hydroclimate-sensitive sedimentary archives to assess the impact of climate change in the Mediterranean region.
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