Abstract:
Using digital photographs, this study investigates sediment movement eastwards
by the dominant northwest swell in Freshwater Bay, WA. Twenty samples were taken at
five locations and analyzed with the Cobble cam analysis package. It was found that sand
and smaller pebbles were more prevalent on the western updrift shore than on the delta
face and that no silt and clay were found on the foreshore. Sand was not evident on the
most eastern site and mean sediment grain size increased eastward. Wave rays hit the
western face of the delta orthogonal to the shore and result in more pronounced cusps in
the eastern direction. The westerly portion experiences oblique waves and results in
longshore transport eastward in Freshwater Bay. Pacific Ocean swell from the west had
the most impact while local wind-generated waves from the northeast and northwest had
the least. Pebbles were selectively moved by the wave regime for each section of beach.
All the sediment along the western delta was removed and indicates that longshore
transport is sediment starved.
