Wave climate variability and longshore sediment transport on The Doce river delta coast (Brazil)

Wave climate variability and longshore sediment transport on The Doce river delta coast (Brazil)

Polizel, S.P. (University College London, UK)
Burningham, H. (University College London, UK)

2021-06-28

Deltas are prograding landforms that exist at the interface between rivers and open water systems (marine or lake) and are formed by the deposition of great loads of fluvial sediments. Depending on the influence of the dominant process, deltas can be classified as river-, tide-, or wave-dominated and they will display distinct morphologies (Galloway 1975). This work focus on a wave-dominated delta system and this type of delta occurs on coasts with a large influence of wave processes, in which the sediments brought by the fluvial channel are rapidly redistributed by the wave action along the adjacent shorelines. They present sand ridges parallel to the shore, forming beach-ridge plains, a protrusion shape near the river mouth (Nicholls et al. 2007; Seybold et al. 2007), and are also characterised by smooth shorelines (Anthony 2015). One of the main processes driving change in delta shoreline and coastal morphology is the wave-driven longshore sediment transport. Assessing the wave climate variability and its implications for direction dominance in alongshore movement of sediment is key to understanding sediment source - supply - morphological change linkages along sediment-rich deltaic coastlines. Marine processes not only contribute to the fluvial sediments rework and redistribution, but also are responsible for the mobilisation of nearshore deposits. These deposits are then incorporated into the deltaic sediment budgets and transported alongshore (Anthony 2015). However, much still remains to be known regarding the relationship between waves and delta morphodynamics. Deltas are inherently dynamic systems and they change over multiple spatial and temporal scales. Therefore, quantifying the sediment transport at the vicinity of their river mouth and along the coast it is not a simple task considering the complexity of these coastal environments (FitzGerald et al. 2000). In addition, investigations of the marine processes and the associated sediment transport pathways are important to understand the shoreline behaviour, as well as the evolution of deltaic coastlines (Oliveira et al. 2015). Within this context, the aim of this study is to describe the relationship between wave climate variability and the littoral sediment transport along the Doce River delta coast for two different wave forcing.

Coastal hydrodynamics (waves, tides and surges)
Coastal sediment transport (subaqueous and aeolian)

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