Poster 174 – Click on poster below to view presentation from author.
North Carolina State University
Co-Authors: Barbara Doll, Jack Kurki-Fox, Melanie Carter
Streambank erosion can be the most significant source of in-stream sediment loads contributing between 17 to 92% of the total load. Often restoration groups seek to direct restoration efforts to streams with the greatest potential for reduction of downstream sediment loads. Similarly, many cities want to allocate stormwater fees towards stream restoration efforts intended to reduce the impacts of erosion to downstream reservoirs, public utilities and private property. Prioritizing streams for restoration often require survey and assessment of hundreds of miles of streams to identify the best suited locations for restoration. Developing a systematic, efficient approach that maximizes desk-top geospatial tools for identifying problem areas that can reduce effort and maximize their limited resources is essential. A potential desktop geospatial procedure for identifying eroding streambanks is the USGS’s recently developed ‘positive openness’ raster dataset for North Carolina which identifies the locations of concave surfaces using high-resolution topographic data to calculate relief angles. Validation of the tool’s ability to identify eroding and unstable streams in urban/suburban watersheds is needed as tree cover and structures may affect surface angle measurements. Erosion rates and volumes can be quantified by time-series analysis of aerial imagery, repeated physical measures of stream geometry, and comparison of LiDAR surveys. These tools for predicting and measuring erosion have not been tested or compared to see if they yield similar results. While the BEHI method is widely applied, validation by comparing the predictions to measured erosion rates has been limited. Preliminary study results will be presented examining if BEHI and NBS predict future erosion rates or capture past events, if positive openness can accurately identify eroding streams and comparing methods to quantify erosion rates.
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