DETECTION OF HOLOCENE LAKES IN THE SAHARA USING SATELLITE REMOTE-SENSING

During the Holocene warm optimum, the Saharo-Sahelian limit tvas located at 22 degrees to 23 degrees N latitude, sahelian biotopes and surface wafer being recorded ah across the current southern Sahara. The extension of lakes during the last warm Holocene optimum is related to the range and frequency of monsoonal rains and/or of Atlantic cyclones. Our objective is to produce a record of Holocene surface water extension in an area presently hyperarid. This study demonstrates the feasibility of detecting the localization of paleolakes by analyzing the spectral information of remotely sensed data. The spectral signature of evaporitic deposits related to the drying up of paleolakes is separable in the red and near-infrared wavelengths from the spectral signature of the surrounding land-cover classes. The most appropriate spatial resolution - in the range of resolution cell sizes of current sensors - to discriminate the residual records of paleolakes is 80 metres.