STUDIES ON THE ENVIRONMENTAL CHANGE AND HUMAN ACTIVITIES IN SEMI-ARID AREA OF AFRICA

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This research project sought to determine the environmental history of the semi-arid area of Namibia from the Last Glacial stage, and recent environmental changes, including changes in climate, topography, vegetation, soil, land utilization, and agriculture.(1)The relationship between the environmental change and the dead tree was surveyed in the Kuiseb River basin. It was considered that sand deposited by flood and change of environments affected the dead trees.(2)Factors controlling the changes in vegetation structure of savanna vegetation in Namibia were clarified in macro-and meso-scale. The geographical distribution of the various savanna types in Namibia was principally controlled by two different factors that are independent of the amount of annual precipitation : the water-holding capacity of the soil and ecological characteristics of Mopane.(3)The paleohydorological environmental changes of the Kuiseb river basin was investigated in Namib Desert. The fluvial land forms and the soil profiles on each geomorphic surface were examined at middle course of the Kuiseb River in order to estimate the paleoenvironmental condition.(4)The origin of the fog was surveyed in Namib Desert. In the daytime, the air which is comparatively moist because of sea breeze moved to the inland, and it is solidified by radiative cooling in the night. The water vapor runs the fog and it is blown by the land wind to the westward.