Photo Electronic Erosion Pin (PEEP) Data Processing for Revealing Stream Bank Retreat

The purpose if this study is to develop a methodology for quantifying stream bank erosion using Photo Electronic Erosion Pin (PEEP) that could adequately capture retreat length magnitude and timing information in response to changes in water stage. PEEP’s operational principle is based on sunlight exposure and intensity (“photo”=light).Four PEEPs were inserted into the stream bank near the mouth of Clear Creek, Iowa City, USA. PEEPs B1, B2, B3, and B4 were deployed at the crest, upper midbank, lower midbank, and toe of the right bank, respectively. The deployment of PEEP has been complemented with a statistical treatment of the retreat length time series data through the performance of a moving average to identify ubiquitous key bank erosion events in terms of magnitude and their frequency of occurrence for bank erosion. In concert to this effort, a unique and systematic PEEP data processing routine (e.g., filtering, correcting and smoothing) has been also developed to remove the effects of ambient light changes due to solar orientation, or equivalently low light intensity and other factors (e.g., turbidity) on the bank retreat length estimation. This monitoring activity successfully recorded the frequency and retreat length at these locations which occurred between June 4 and December 1, 2009. The numbers of erosion events were 8, 4, 5, and 1 for the crest, upper midbank, lower midbank, and toe of the bank, respectively.