NOAA/WDS Paleoclimatology - Sahara-Sahel Holocene Paleohydrological Database

The examination of more than 1500 paleohydrological dated records collected between 10 and 28°N during the last 50 years have been used to improve our knowledge and understanding of the Sahara and Sahel vulnerability to the Atlantic monsoon changes in the long-term. We have analyzed the distribution of water bodies (mainly lakes and wetlands) over time and space: the central Saharan massifs played a major role in favoring water supply to the lowlands throughout the whole African Humid Period. In addition, distinct East-West dynamics is recorded with humidity starting - and stopping - several millennia earlier to the east than to the west of the Sahara. A series of time lags are discussed: (1) between the maximum of deep (fresh water) lake formation during the early Holocene and the maximum of water body extensions during the mid-Holocene which highlight the primary role of aquifer water level in lake response to climate change (2) between the hydrological history of the Sahara and the Sahel and the forcings - mainly insolation changes - during the early and mid-Holocene which involves complex interactions between remnant ice sheet in the Northern Hemisphere, open water bodies in the Sahara and Sahel and the Atlantic monsoon system. Database of Holocene paleohydrological reconstructions derived from published sources for the Sahara and Sahel, 10°N to 28°N. The former extent of lakes, wetlands and rivers can be reconstructed by a variety of paleolimnological evidence including abandoned shorelines, sediment outcrops, aquatic pollen types from sediment cores, remains of aquatic faunas such as hippos, fishes and shells, and former fluvial terraces. Paleohydrological variations can also be inferred from paleosalinity reconstructions from micro-faunal assemblages (diatoms, chironomids, ostracods) and stable isotope ratios in carbonates. This data set is composed of 1688 dated samples from about 415 localities in the present day Sahara and Sahel, extracted from original published studies. The file has been slightly modified from the original version used for the paper: new references have been included, and unpublished data have been removed.