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PROBLEMS OF GEOMORPHOLOGICAL MAPPING Geographical Studies No. 46, Warszawa 1963

LEN BERRY Khartoum

GEOMORPHOLOGICAL MAPPING IN ARID AND SEMI-ARID

REGIONS OF THE SUDAN (EAST AFRICA)

The problems associated with geomorphological work in the Sudan appear to be typical of those in underdeveloped countries everywhere. Other special problems are imposed by the climatic and physical condi-tions of the area. As in many semi-arid and underdeveloped countries the Sudan is only just making headway on the national task of construct-ing good large scalę maps. A vast amount of work has been completed in the last few years but attention has necessarily been concentrated on the areas scheduled for immediate developments. Thus most of the country is only covered by old maps on the scalę of 1 : 250,000 and these are sometimes inaccurate and always out of datę.

Under these circumstances the geomorphological mapping attempted has often been the first detailed map of the region and of course has not had the wealth of topographic, geological and pedological background data which is usually available in other countries. Even under these circumstances it has been found that geomorphological mapping has been successful in representing the features of the area and such maps have been used by workers in other fields.

The mapping carried out by the author has been based on field studies and air-photo interpretation though the use of aerial photographs has been to tracę the aerial distribution of features recognised and re-corded in the field. In field and laboratory work for the Red Sea coast Dr J. S e s t i n i, a geologist, acted in co-operation.

The Sudan has an active aerial survey department with its own aerial photographic team and eąuipment and large parts of the country have now been covered with good ąuality vertical air photographs on scales of 1 :40,000 and in some areas 1 : 25,000. These form the most essential tool to geomorphological mapping acting as a base map on which field data can be plotted.

The most effective field techniąue has been found to consist of (a) preliminary field investigation, (b) the construction of an outline map of the area from air photos, (c) detailed field mapping of features in the field, (d) completion of map and finał drafting of map with the aid of