Assessing Streambank Stability of Oklahoma Ozark Streams with Rapid Geomorphic Assessments

摘要

Streams in the Ozark Ecoregion naturally meander and have a high degree of sinuosity. Changes in land use have resulted in accelerated rates of streambank erosion. Numerous benefits may be achieved from streambank stabilization, but more information is needed on the most critical locations for investing limited funds. Rapid geomorphic assessments (RGAs) are indices proposed to aid in prioritizing sites. This research (1) evaluated two RGAs, the Bank Erosion Hazard Index (BEHI) and the Channel Stability Index (CSI), on several stream sites along the Barren Fork Creek and Spavinaw Creek, and (2) developed a new RGA specific to the ecoregion. The performance of the RGAs was assessed based on lateral bank erosion estimated from five years of aerial photography. Correlations between the existing RGAs and lateral bank erosion were relatively low with coefficients of determination, R~2, of 0.23 and 0.19 for CSI and BEHI, respectively. The two RGAs failed to indicate the same reaches as the most unstable. Primary limitations were not considering the streambank's cohesion and the difficulty in accurately assessing some metrics. Therefore, the Ozark Stream Erosion Potential Index (OSEPI) was developed by including parameters to account for bank cohesion and stream curvature. The OSEPI had the highest correlation (R~2 of 0.31 for all sites; R~2 of 0.46 for sites with similar soils) to measured streambank erosion and aided in prioritizing sites.