Numerical Modeling of Sedimentation by Storm Waves at Sand Island in Lake Superior, Wisconsin

Abstract

This paper describes numerical modeling of the combined wave-flow-sedimentation conducted for relocation and design of a marine boat dock facility located at the eastern shore of Sand Island in the southwestern region of Lake Superior in USA. The present boat dock is situated near a creek that supplies watershed sediments and occasional landslides which cause intermittent burial of land-connection section of the dock facility. The U.S. Department of Interior’s National Park Service is considering a new dock location south of the existing dock to avoid future potential sedimentation from the nearby creek. The role and impacts of local winds, waves, currents, and water levels affect utilization of the new dock. The relocated dock is investigated in the present study using the Coastal Modeling System, an integrated numerical modeling system that includes a spectral wave model and a depth-averaged circulation model with sediment transport calculations. The modeling considers winter storms for two real time periods and a representative condition for 50-yr design return period. The study results are quantified in terms of differences for waves, currents and morphological changes between the existing dock and relocation site. The shadowing effect of the northern headland on waves at these sites was investigated. Results showed minor differences between the existing dock and relocated dock for nearshore waves, current speeds and bed changes.