Cascadia CoPes Hub Virtual Seminar Series September 4, 2025

Large-scale Evolution of Sandy Beaches in the U.S. Pacific Northwest: Understanding and Hindcasting the Past and Forecasting the Future

Speaker: Mohsen Taherkhani

Abstract:  Sandy beaches are highly dynamic environments that evolve from daily to multi-decadal scales, affecting the sustainability of coasts that provide ecological, economic, and recreational benefits to coastal communities. Given their importance, fully understanding the mechanisms driving sandy beach evolution and predicting potential changes is crucial. The U.S. Pacific Northwest (PNW), the focus of this study, has long faced coastal hazards, including erosion on episodic (short-term) and chronic (long-term) scales, threatening coastal resilience. In this study, I quantify current and future erosional hazards along the PNW sandy beaches by analyzing shoreline positions as indicators of beach health and stability, leveraging an extensive historical satellite-derived shoreline position dataset (1984–2024) via a three-step methodology [described below]. These probabilistic, scenario-centric shoreline trajectories provide stakeholders and policymakers guidance for resilient adaptation strategies to address existing and emerging coastal challenges in the PNW.