Chapter 3. Variable rivers: a new geomorphology? Case of the Mfolozi River, South Africa
5. Conclusions
The Mfolozi River Floodplain expands our understanding of wetland formation within southern Africa. The Floodplain is unlike its northern hemisphere compatriots due to a combination of climatic factors and continental uplift followed by variation in sea level.
The absence of peat in regions of overbank flooding can be mostly attributed to the highly seasonal nature of flood flows, and indeed, the irregularity of overbank flooding on the floodplain. This results in long periods of desiccation that cause aerobic decomposition of plant matter. Furthermore, there is evidence to suggest that the Mfolozi River floodplain has adapted geomorphically to its highly variable flow regime, and that the morphology of the river is not in equilibrium with normal flow conditions. It appears that irregularly large flood events may be responsible for the majority of geomorphic change in the upper and middle floodplain, causing avulsions and massive deposition.
The evolution of the floodplain also differs considerably from the dominant model of floodplain evolution in southern Africa of Tooth et al. (2004). The Mfolozi Floodplain is a region of sediment infilling and aggradation, rather than lateral erosion and long-term incision.
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