A Process-Geometric Bluff Erosion Potential (BEP) Index for the Pennsylvania Coast of Lake Erie, USA

Authors: Anthony M Foyle*, Penn State Erie - The Behrend College, Sean D Rafferty, Pennsylvania Sea Grant, Michael D Naber, Penn State Erie - The Behrend College
Topics: Coastal and Marine, Hazards and Vulnerability, United States
Keywords: coastal erosion hazards, bluffs, Great Lakes
Session Type: Poster
Day: 4/13/2018
Start / End Time: 1:20 PM / 3:00 PM
Room: Napoleon Foyer/Common St. Corridor, Sheraton, 3rd Floor
Presentation File: No File Uploaded

The BEP Index is a geometric model of coastal bluff-erosion potential being developed for Pennsylvania's Great Lakes coastline. It estimates the position of the bluff crest at incremental future points in time, and maps erosion hazard swaths along the coast, using average annual retreat rates (AARR) and natural regrading of the bluff face toward more stable slope angles (SSA). It is based on easily measured land surface characteristics and on inferences about slope stability for unconsolidated bluffs typical of the Pennsylvania coast. The land surface characteristics are mapped and extracted from LiDAR-based DEMs and aerial imagery using transect-generating geo-sampling software, such as DSAS within ArcGIS. The Index incorporates the following mappable attributes: present bluff slope (PBS; reflects stability state) and watershed bluff-slope average (WSA); shale toe occurrence and height (affects bluff resistance to wave erosion); AARR at the bluff crest (reflects the net response of the bluff system to driving and resistive forces); present bluff-crest location (the reference feature for estimating future bluff-crest locations); two reference end-member SSAs (an 18.5' slope based on planning practices on the Great Lakes; a 33' slope based on generalized bluff geotechnical properties); and an assumed horizontal-planar tableland landward of the bluff (for geometric simplicity). These observable and derivable bluff characteristics are the product of a large number of interacting, spatially and temporally variable, environmental conditions and processes that are otherwise difficult to measure economically or in statistically meaningful ways. The Index is being developed to improve bluff-erosion hazard visualization along Pennsylvania's Great Lakes coast.

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