Plant assemblages rooted within channels, as well as in peat deposits flanking channels, in the northeastern Okavango Delta have been classified and their distribution related to environmental conditions. Within-channel assemblages appeared to be related to the introduction of sediments from source areas and to differences in channel dimensions (particularly water depth) and current velocity. Channel margin assemblages appeared to be related to seasonal and longer-term water level fluctuations, as well as the extent to which water, introduced from either the catchment or from local rainfall, contributed to the water budget. These two classifications have been combined in a functionally based classification of channels in the study area in which five channel types were recoganized; long-term and short-term aggradational, primary filter and confined and unconfined outlet channels. Comparison of these channel types with an earlier classification by Wilson (1973) has indicated some degree of correspondence. A number of changes in the spatial distribution of similar channel types have, however, taken place since the earlier study, mainly in the upper reaches of the study area. The reasons for these and possible short-term future change have been inferred based on the findings in the present study.
