Hood, W.G., 2010. Tidal channel meander formation by depositional rather than erosional processes: examples from the prograding Skagit River Delta (Washington, USA). Earth Surface Processes and Landforms: The Journal of the British Geomorphological Research Group, 35(3), pp.319-330. [NOTE: The download link for this document leads offsite]

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Channel meander dynamics in fl uvial systems and many tidal systems result from erosion of concave banks coupled
with sediment deposition on convex bars. However, geographic information system (GIS) analysis of historical aerial photographs
of the Skagit Delta marshes provides examples of an alternative meander forming process in a rapidly prograding river delta:
deposition-dominated tidal channel meander formation through a developmental sequence beginning with sandbar formation at
the confl uence of a blind tidal channel and delta distributary, proceeding to sandbar colonization and stabilization by marsh
vegetation to form a marsh island opposite the blind tidal channel outlet, followed by narrowing of the gap between the island
and mainland marsh, closure of one half of the gap to join the marsh island to the mainland, and formation of an approximately
right-angle blind tidal channel meander bend in the remaining half of the gap. Topographic signatures analogous to fl uvial meander
scroll bars accompany these planform changes. Parallel sequences of marsh ridges and swales indicate locations of historical
distributary shoreline levees adjacent to fi lled former island/mainland gaps. Additionally, the location of marsh islands within
delta distributaries is not random; islands are disproportionately associated with blind tidal channel/distributary confl uences.
Furthermore, blind tidal channel outlet width is positively correlated with the size of the marsh island that forms at the outlet,
and the time until island fusion with mainland marsh. These observations suggest confl uence hydrodynamics favor sandbar/marsh
island development. The transition from confl uence sandbar to tidal channel meander can take as little as 10 years, but more
typically occurs over several decades. This depositional blind tidal channel meander formation process is part of a larger scale
systemic depositional process of delta progradation that includes distributary elongation, gradient reduction, fl ow-switching,
shoaling, and narrowing. Copyright © 2010 John Wiley & Sons, Ltd.

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