Net Shore-Drift of Kitsap County, Washington

Kitsap County is located entirely within the Puget Sound Lowland in northwestern Washington State. It has a crenulated coastline 352 km in length. The Puget Sound Lowland, and Kitsap County in particular, is characterized by glacial landforms and sediments. Glacial activity is responsible for the shape and depth of the various water-bodies comprising Puget Sound, which is subject to mixed, semi-diurnal tides. Net shore-drift is the process by which sediment, supplied to the margin of a landmass by subaerial and wave-induced erosional processes, is transported parallel to the coast by longshore drift and beach drift over a period of many years. The fetch, the distance of open water over which the wind can blow unimpeded, determines the size of the waves generated by any combination of wind velocity and duration. The maximum fetches to which the shores of Kitsap County are exposed are 48 km in Hood Canal and 56 km in Puget Sound (University of Washington, 1954). There are 99 unit cells of net shore-drift, ranging from 50 m to 26 km in length, in Kitsap County. The pattern of net shore-drift in Kitsap County most closely correlates with fetch, due to the crenulated nature of its coast. The use of geomorphic features and sedimentologic trends as indicators of net shore-drift are far superior to, and more reliable than, wave-hindcasting or mathematical-modeling techniques in determining the direction of sediment transport in such regions