Exploring linkages between coastal progradation rates and the El Niño Southern Oscillation, Southwest Washington, USA

Abstract

Climate oscillations such as the El Niño-Southern Oscillation (ENSO) affect storm tracks, wave climate, precipitation and sea level in the U.S. Pacific Northwest. The impacts of these changes on coastal behavior have not been investigated in detail beyond the study of recent El Niño events, largely because existing historical records of coastal behavior are not of sufficient resolution to study annual responses to climatic forcing. We compare a newly developed annual record of coastal progradation for a location on the Washington coast, generated using high-resolution subsurface ground penetrating radar (GPR , with ENSO indices. This analysis reveals higher rates of seaward coastal growth following the warm, El Niño, ENSO phase and lower rates of coastal growth following the cold, La Niña, ENSO phase. The observed relationship between ENSO and progradation, although weak, is hypothesized to result from differences in sediment transport patterns and beach recovery rates following El Niño and La Niña events.