As Holocene river deltas continue to experience sea-level rise, sediment carried by distributary channels counteracts delta-plain drowning. Many deltas worldwide are subject to tidal action, which strongly affects the morphology of distributary channels and could also influence their mobility. Here we show, through physical laboratory experiments, that distributary-channel mobility can be dramatically reduced in systems affected by tides in comparison to an identical system with no tides, and that the mobility of distributary channels decreases as the ratio of tidal to fluvial energy increases. This effect occurs even if new accommodation space is created by rising relative sea level. By analyzing synthetic stratigraphy derived from both digital elevation data and time-lapse photography, we show also that the reduction of channel mobility in tidal deltas increases channel stacking and connectivity in the stratigraphic record.
Bibliographical noteFunding Information:
This work was supported by the U.S. National Science Foundation (NSF) via the Delta Dynamics Collaboratory (grant EAR-1135427 to Paola); by the BanglaPIRE project, NSF Partnerships for International Research and Education (grant IIA 09-68354 to Paola); by the University of Padova (grant BIRD 168939 to Finotello); and also by the St. Anthony Falls Laboratory Industrial Consortium for Experimental Stratigraphy (Paola). Additionally, the publication of this paper was supported by the ExxonMobil Exploration Company. We are grateful for constructive reviews from M. Kleinhans, S. Goodbred, A. Cantelli, and P. Plink-Bj?rklund, which substantially improved this paper