Is It Possible To Maintain A Megalake Chad At Mid Holocene ? Analyses Of Model Simulation At 6ka With Emphasis On Hydrologic Cycle variation

The orbital forcing variations through Holocene may explain the shift in latitude of the ITCZ and its seasonal variations. This feature has been depicted by many modeling studies. There is also many data over continental areas (Africa and South America) that depict the changes in ITCZ through the whole Holocene. In this study we use a coupled Atmosphere-Ocean-Biosphere General Circulation Model (IPSL) to simulate the climate of Mid-Holocene (6Ka BP).Our main goal is to focus on the response of Chad Lake to the hydrologic changes due to orbital parameters variations. We show that the induced changes in ITCZ location and on hydrology around the Lake are consistent with the existence of a Megalake 6000 years ago. We then discuss the periodicity of the occurrence of a Megalake since there are evidences that such variations occurred since Mid-Miocene and the possible modulation of these oscillation due to tectonics (uplift of the African rift and variation in the Indonesian throughflow.