Foredune Erosion on the Duluth-Superior Barrier System: A GPR Analysis

Keywords: GPR, foredunes, erosion
Abstract Type: Poster Abstract

Abstract

The Duluth-Superior Barrier System (DSBS) located along the southwest side of Lake Superior in Duluth, Minnesota, and Superior, Wisconsin, is one of the largest freshwater barriers in the world with immense environmental and economic importance. Located on the Minnesota side is Park Point, a beach-facing neighborhood on the barrier system. Increased lake levels, longshore drift, and human modification threaten the DSBS, leaving it vulnerable to further erosion, impacting the coastlines, the homes and lives of those living on Park Point, and the entire ecosystem.

Formed by aeolian processes foredunes are dune ridges parallel to the shore, anchored by vegetation. Foredunes stabilize and restrict the amount of sediment moved by wind or wave erosion. Without dunes, the DSBS is at risk for significant beach degradation. The fragility of foredune ecosystems makes the DSBS an ideal candidate for Ground Penetrating Radar (GPR), a non-invasive tool using EM radio pulses to create near-surface cross-section profiles. GPR profiles of the DSBS were collected using Sensors and Software pulseEKKO Pro 100 system at frequencies of 500 MHz and 100 MHz and topographic data using Topcon RL-H4C laser level. Profiles were then processed and interpreted with EKKO_Project5 software. GPR lines and topographic data from the northern and middle sites of the DSBS suggest sediment loss on the northern side and sediment gain and dune growth near the middle. The results of this study aim to help better understand the geomorphic processes influencing the barrier system and encourage stakeholders to take action to preserve the DSBS.