Abstract

River deltas are arguably some of the most important environments on Earth; they are ecologically rich, usually contain hydrocarbons in the subsurface, and support ~10% to 25% of the world’s population. River deltas form on shorelines where sediment can accumulate faster than it is taken away and are recognized by the presence of a distributary channel network or a bump that protrudes from the shoreline. Subaerial parts of river deltas grow by the processes of levee formation, river mouth bar deposition, avulsion, and organic and fine-sediment matter accumulation. The resulting balance of these processes, determined by upstream and downstream boundary conditions, sets the delta shape. Looking forward, the future of deltaic environments is grim under current estimates of relative sea-level rise. In order to protect these important environments, we must understand delta processes and shapes so that restoration schemes can be designed to take advantage of them.