Physics and chemistry of arc magma| arc volcanism in time and space| geothermal and energetic aspects of arc volcanism| prediction, hazards and environmental aspects of volcanic activities. Fifteen selected papers.
The Sahelian area is characterized by a high rainfall variability in time and space. Dry or wet spells are recurrent phenomena. The drought of 1968-1982 culminating in 1972-1973 then in 1982, exceeds all the previous drought periods in magnitude
phase| an apron phase, in wich the channel was obliterated and a rechannelized phase. Probable trajectories of the Rupert Inlet and Redondo systems in slope-discharge parameter space are proposed and illustrate the importance to the occurrence