River delta morphotypes identified from unsupervised clustering of the shoreline morphometric space (SMS).
It has long been posited that the observed diversity in the shapes of river deltas reflects the relative strength of river and marine energy. However, rigorous quantification of the relation of delta morphology and flux partition is still lacking. Here we introduce a new multiscale geometric framework which characterizes river delta morphology via its shoreline structure and separate deltas into clearly distinct morphological classes called morphotypes which align with qualitative classifications of delta shape. We then examine how the shoreline classes contrast with the estimated, modern relative sediment transported by rivers, waves, and tides in order to understand the relationship between the two frameworks. This assessment shows that the shoreline reflects spatiotemporal heterogeneities in the historical sediment transport budget that the modern budget doesn't capture and provides insight into sediment transport estimate uncertainty. The proposed framework enables easy and quantifiable delta classification based on readily-available remote sensing images and is fundamentally important for predicting deltaic geomorphic response to changing forcings.
Vulis, L., A. Tejedor, H. Ma, J. Nienhuis, C. Broaddus, J. Brown, D. Edmonds, J. C. Rowland, and E. Foufoula-Georgiou, River delta morphotypes emerge from multiscale analysis of shorelines, Geophysical Research Letters, 50, e2022GL102684, doi:/10.1029/2022GL102684, 2023