Madeline Kollegger, Jorge Lorenzo-Trueba , Anjali M Fernandes , Arvind Singh, Antoinette Abeyta

Stratigraphic interpretation generally relies upon the assumption that the fluvio-deltaic surface responds uniformly to sea-level changes; however, recent theoretical work suggests that changes in its relief and concavity can influence the propagation of sea-level information upstream and result in geologically long-lived lags in the system response. We test this theoretical result using measurements from a experimental delta subject to high and low magnitude sea-level oscillations. In both cases, changes in relief and curvature of the fluvio-deltaic profile result in the proximal portion of the profile being out of phase with respect to sea-level cycles, whereas the nearshore regions remain in phase. These results underscore the importance of delayed response to sea-level variations in the upstream portion of river deltas, often resulting in net erosion during sea-level rise and potentially complicating the reconstruction of paleo sea-level from deltaic deposits.