COASTAL FLOOD STUDIES IN PUGET SOUND, WASHINGTON STATE, U.S.A

摘要

A series of coastal flood insurance studies are being conducted in Whatcom County, Washington to identify existing coastal flood hazards. The coastal flood study of Sandy Point was given the highest priority because of pending development interests and flood risk. This paper describes the methods and findings from this study. The coastal flood study consists of a series of phases. The scoping phase involves efforts to obtain and review data, perform a site reconnaissance and refine the methodology for the project. The tidal hydrology phase includes statistical evaluations of tidal and wind data to establish return period stillwater elevations and wind speeds. The coastal hydraulics phase includes an estimation of deepwater wave parameters, an analysis of wave refraction and shoaling, and a nearshore breaking wave height analysis. Field surveys were conducted to define beach and inland elevations for the estimation of wave runup and overtopping conditions during the 100-year flood event. The hazard mapping phase has resulted in preliminary flood hazard maps for the Sandy Point study area. Coincidently, during the study an estimated 20-year coastal flood event occurred at Sandy Point. The flood event provided a unique opportunity to verify flood study methods and has led to the modification of some standard FEMA coastal procedures for Pacific Northwest coastal flooding.