The sediment stratigraphy of a flood event: An example from the Sabie River, South Africa

- Recent floods on the Sabie River left diagnostic sediment signatures.
- Flood sediment stratigraphy is described for the first time.
- Both rising and waning flows are captured in the stratigraphy.
- An extensive organic layer represents final flood stages.
- This flood stratigraphy may be typical of semi-arid rivers.

The geomorphic effects of river floods in various climatic settings worldwide have been extensively described, but there is little information on sedimentary processes during and immediately following flood peaks. Here we reconstruct sedimentary processes and patterns of the 2012 flood on the Sabie River in Kruger National Park, South Africa, from the preserved geomorphic and sedimentary signature of this event. Based on a combination of geomorphic and sedimentary evidence, the maximal and waning flow stages of the flood event are identified, shown by cut and fill and fining up sequences within aggradational bars, and organic horizons, which may be buried, that correspond to the period of flood peak recession. The presence of organic horizons suggests a strongly seasonal flow regime typical of semi-arid South African rivers. It also provides an exemplar of a flood event stratigraphy that is usually poorly preserved in the geologic record.