A preliminary evaluation of dry season/drought status in the Sahelian zone of Mali, Mauritania and Senegal, based on ERTS-1 imagery

A first look analysis of 6 scenes (11-16 April) in the northern margin of the Sahelian zone in western Francophone Africa confirms and is consistent with late dry season manifestations. Because the 1973 late dry season follows a period of rainfall deficit, an attempt is made to distinguish between normal late dry season and drought conditions. The aims of the analysis were (1) to evaluate the status of the dry-season/drought, and (2) to indicate areas in which ERTS-1 imagery analysis might provide potential support for remedial actions. 1. Vegetation. Preliminary analysis of the status of vegetation in the Sahelian zone as determined from ERTS imagery was analyzed in two steps. First, the presence of vegetation two selected regions in the Sahelian zcme southern Mauritania and Mali in the region near Diema, was determined from composites of cyanl:-and magenta diazo transparencies prepared from MSS bands 7 and 5. In these composites of October (Diema)and March (Mauritania) regions of living vegetation can be seen as shades of red, with the shade varying according to the density and type of vegetation. Crop vegetation can be distinguished primarily by its pattern and knowledge of planting and cropping patterns in the regions. Brush vegetation