MODELING INTERANNUAL TO MULTI-DECADAL SHORELINE ROTATIONS OF HEADLAND-BOUNDED LITTORAL CELLS

摘要

Shoreline modeling of headland-bounded littoral cells in the U.S. Pacific Northwest (PNW) suggests that interannual to multi-decadal coastal change is driven by wave climate variability dominated by the El Ni?o Southern Oscillation and possibly by the Pacific Decadal Oscillation. Alternating alongshore-directed wave power results in counter-clockwise shoreline rotations during El Ni?o winters, and clockwise rotations during La Ni?a winters. The cumulative effect of successive winters with similar ENSO conditions results in longer term trends. Annual shoreline movements are relatively large and highly dependent on the phase of ENSO in close proximity to headland boundaries, but these changes are superimposed on interannual to multi-decadal trends associated with large-scale climate variability that have even a greater effect on shoreline evolution. These results suggest that possible climate change impacts on the 21st century wave climate may play a significant role on future shoreline evolution in the PNW.