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Quantifying the patterns and dynamics of river deltas under conditions of steady forcing and relative sea level rise
Author(s) -
Liang Man,
Van Dyk Corey,
Passalacqua Paola
Publication year - 2016
Publication title -
journal of geophysical research: earth surface
Language(s) - English
Resource type - Journals
eISSN - 2169-9011
pISSN - 2169-9003
DOI - 10.1002/2015jf003653
Subject(s) - channel (broadcasting) , delta , river delta , context (archaeology) , beach morphodynamics , environmental science , hydrology (agriculture) , sediment , geology , sediment transport , geomorphology , geotechnical engineering , computer science , computer network , paleontology , engineering , aerospace engineering
Understanding deltaic channel dynamics is essential to acquiring knowledge on how deltas respond to environmental changes, as channels control the distribution of water, sediment, and nutrients. Channel‐resolving morphodynamic models provide the basis for quantitative study of channel‐scale dynamics, but they need to be properly assessed with a set of robust metrics able to quantitatively characterize delta patterns and dynamics before being used as predictive tools. In this work we use metrics developed in the context of delta formation, to assess the morphodynamic results of DeltaRCM, a parcel‐based cellular model for delta formation and evolution. By comparing model results to theoretical predictions and field and experimental observations, we show that DeltaRCM captures the geometric growth characteristics of deltas such as fractality of channel network, spatial distribution of wet and dry surfaces, and temporal dynamics of channel‐scale processes such as the decay of channel planform correlation. After evaluating the ability of DeltaRCM to produce delta patterns and dynamics at the scale of channel processes, we use the model to predict the deltaic response to relative sea level rise (RSLR). We show that uniform subsidence and absolute sea level rise have similar effects on delta evolution and cause intensified channel branching. Channel network fractality and channel mobility increase with higher‐RSLR rates, while the spatial and temporal scales of avulsion events decrease, resulting in smaller sand bodies in the stratigraphy. Our modeling results provide the first set of quantitative predictions of the effects of RSLR on river deltas with a specific focus on the distributary channel network.

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