Recent environmental changes and human impact since mid-20th century in Mediterranean lakes: Ifrah, Iffer and Afourgagh, Middle Atlas Morocco

摘要

The multidisciplinary study of sediment cores from three middle Atlas lakes (central Morocco) provides a detailed record of environmental, climatic and anthropogenic changes. The paleohydrological reconstructions show fluctuating lake level since the mid-20th century. Human activities have played a significant role in the lakes' hydrological changes. The sedimentology, geochemistry and mineralogy results show three main periods. The first period between 1900 and 1920 is humid with high lake levels, with fine particle size and relatively high contents of organic matter. The second period between 1920 and 1965 is very unstable with varying humidity. The last period between 1965 and 2000 is characterised by increasing human activities (clearing of forest and development of agricultural techniques). This last phase was interrupted by some humid years or sub-periods (between 1976 and 1980, between 1995 and 1996) and dry years (between 1980 and 1990, between 1994 and 1995). This study provides an opportunity to evaluate the relative significance of human and climatic factors in middle Atlas lakes during the 20th century.