Response of a Tropical Wave-Dominated Delta to a Major Flood Event: The Case of Doce River Delta Coastline (Southeastern Brazil)

Polizel, S.P. and Burningham, H., 2024. Response of a tropical wave-dominated delta to a major flood event: The case of Doce River delta coastline (southeastern Brazil). In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 341-345. Charlotte (North Carolina), ISSN 0749-0208. Shorelines adjacent to deltaic river mouths are sensitive to variability in marine and fluvial processes. Quantifying and understanding climate change impacts across the delta watershed is crucial when considering frequency and magnitude of riverine flood events that might impact the delta coast, and evaluation of shoreline response to major flood events is important for coastal planning and catchment management. Investigations here took a multisensor earth observation approach to examine monthly changes in configuration and morphology of the Doce River delta mouth and adjacent shoreline for the period between June 2021 and September 2022, encompassing around 7 months before and after the mid-January 2022 flood. The overall shoreline behaviour over this period involved advance of the shoreline at the river mouth and along a few other stretches, but a predominance of erosion along the adjacent delta shoreline, with notable differences in magnitude north and south of the river mouth. Before the flood, around 60% of the shoreline exhibited progradational patterns; following the event, over 85% of the coast was experiencing erosion with an average shoreline retreat calculated by the net shoreline movement (NSM) of -20.4 m (over 8 months). This study highlights areas that are more prone to coastal hazards due to river delta flooding, and stresses the important influence of significant flood events on adjacent shoreline change.