Multi-scale characterization of inland valley agro-ecosystems in West Africa

Abstract

Inland valleys are the upper reaches of river systems, comprising valley bottoms and minor floodplains, their hydromorphic fringes, and contiguous upland slopes and crests. Valley bottoms and hydromorphic fringes are estimated to occupy between 22-52M ha of land in West Africa. In spite of their potential for agricultural use, they are only marginally used and with limited success. We propose a multi-scale geo-ecological characterization with increasing detail at four levels: macro level (scales between 1:1 000 000 and 1:5 000 000), reconnaissance level (1:100 000-1:250 000), semi-detailed level (scales 1:25 000-1:50 000), and detailed level (1:5000-10 000). Methods of characterization at each of these levels are discussed, and examples of actual applications are given, as well as the mechanisms applied in desaggregation (scaling down) and aggregation (scaling up) between characterization levels. Agro-ecological characterization of inland valleys carried out so far, shows that variation in (bio)physical and land use factors is considerable, both between levels and within valleys. -from Authors