Determination of Sediment Loading Potential to Pennsylvania Lake Erie Coastal Waters Due to Bluff Erosion and Storm Water Discharge Ravines
Lake Erie Shoreline, PA

Grantee: Edinboro University of Pennsylvania
Basin Program Funds: $23,688
Non-federal Funds: $10,450
Project Duration: 07/1999 - 06/2001
Status: complete

Problem Statement
Bluff erosion is taking place along the forty-seven miles of Pennsylvania's Lake Erie shoreline. Although there is an increasing awareness of the cause and effects associated with bluff erosion, there remains an inadequate understanding of the character of the sediments eroded and discharged into the waters of Lake Erie.

The rate of erosion taking place along Pennsylvania's Lake Erie shoreline varies with stratigraphy, ground water discharge, land use and topography. A certain amount of bluff erosion is related to naturally occurring forces. However, bluff erosion is also related to discharges of stormwater into ravines and other uncontrolled surface and subsurface discharges. Also, removal of vegetation for scenic viewing or the construction of trails and roads across the bluff destabilize the slope and promote accelerated erosion.

There is a lack of knowledge about bluff stratigraphy in the Pennsylvania coastal zone. Because certain stratigraphic sites are more vulnerable to erosion and contain higher silt/clay fractions, coastal managers need to add this missing aspect to their knowledge base. It is important to determine bluff height, slope, geometry, and stratigraphy, including an analysis to determine percentage of sand, silt, and clay in each stratigraphic layer. This project built on an existing and evolving database. Since 1973, the Pennsylvania Coastal Zone Management (CZM) Program has been actively involved in projects increasing the understanding of bluff erosion. The program established bluff erosion control points every 0.5 kilometers along the Lake Erie shoreline. The amount of recession that occurred each year between 1982 and 1998 is known.

Project personnel established a monitoring grid consistent with the Pennsylvania CZM Program to provide for stratigraphic variations within each major reach. Gathered data include the global positioning system location, bluff slope, stratigraphic sections present, thickness of each section, degree of erodibility, presence of groundwater, vegetative cover, land use in the upland and the general geometry of each site. Project personnel have also collected and analyzed samples of sediment from each stratigraphic unit to test for sand, silt and clay fraction composition. By combining the results of the analyses with the amount of recession occurring between 1982 and 1998, project staff estimated the sediment loading along the Pennsylvania reach. This information provided the necessary basis for promoting erosion reduction programs with landowners, developers and municipalities. The recession monitoring program is an on-going effort by the Pennsylvania Department of Environmental Protection and by individual research efforts of Edinboro University and Penn State University. Additional control points have been established. As more is learned about the sediment character of the coastal bluffs, a growing understanding of the amount of silt and clay reaching Lake Erie will be possible.

As a result of bathymetric analysis of the near shore profile, project personnel determined the amount of sediment loading in the form of sand sized fractions is much less than originally anticipated. A very accurate determination of recession rates was obtained on the selected sampling stations. All information gathered from this study was published in a report containing maps, diagrams, and data including estimates of sediment loading in the coastal zone. Project personnel estimated reaching an additional 500 agency, elected officials, shoreline property owners and researchers with the study results. Protection of the eroding shorelines will reduce the amount of silt and clay reaching Lake Erie, but will reduce the amount of beach building material in the littoral system, thereby increasing shoreline erosion. The results of the project were, in some ways, surprising because the amount of sand and gravel contributed by the bluffs was much larger than originally thought. The results of the study have assisted in the development of new initiatives in monitoring Pennsylvania Coastal Zone bluff and shoreline erosion.

Contact: Paul Knuth, (814) 734-1542


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