An example of cartography of runoff capability in the Sahelian region: Sama Dey, Niger

In the tool box of a hydrologist, modelling occupies a privileged place. In the case of distributed hydrological models, a preliminary stage is the pa rtitioning of the catchment into homogeneous spatial units based upon their runoff production capability. A cartographic approach is presented, which combines a soil surface feature map and a slope map. Principles of this met hod are presented and illustrated using the example of the Sama Dey catchme nt (Niger). A first step is to make a map of runoff capabilities which allo ws the definition of contributing areas of the catchment and a proposal for the classification of the hydrological space. A second step is the definit ion of an experimental design using the map partitions, the objective of wh ich is to provide the required data for the hydrological unit characterizat ion.