Delta shoreline structure has long been hypothesized to encode
information on the relative influence of fluvial, wave, and tidal
processes on delta formation and evolution. We introduce here a novel
multiscale characterization of shorelines by defining three
process-informed morphological metrics. We show that this
characterization yields self-emerging classes of morphologically similar
deltas, i.e., delta morphotypes, and also predicts the dominant forcing
of each morphotype. Then we show that the dominant forcings inferred
from shoreline structure generally align with those estimated via
relative sediment fluxes, while positing that misalignments arise from
spatiotemporal heterogeneity in deltaic sediment fluxes not captured in
their estimates. The proposed framework for shoreline characterization
advances our quantitative understanding of how shoreline features
reflect delta forcings, and may aid in deciphering paleoclimate from
images of ancient deposits and projecting delta morphologic response to
changes in sediment fluxes.