USING RAPID GEOMORPHIC ASSESSMENTS TO ASSESS STREAMBANK STABILITY IN OKLAHOMA OZARK STREAMS

High streambank erosion and failure rates on streams in the Ozark ecoregion of Oklahoma may be attributed to land use change and degradation of riparian areas. Numerous benefits may be achieved from streambank stabilization, but methods are needed to determine the most critical reaches for investing limited funds. Rapid geomorphic assessments (RGAs) have been used to aid in prioritizing stream reaches. This research (1) applied an existing RGA, the channel stability index (CSI), on several reaches along the Barren Fork Creek and Spavinaw Creek, and (2) modified the existing RGA to create an ecoregion-specific RGA called the Oklahoma Ozark streambank erosion potential index (OSEPI) for larger-order streams in the area. Aerial photography (2003 to 2008) was used to document recent lateral bank retreat for evaluating the RGA scores. Whereas the CSI provided a relatively simple, inexpensive way to identify reaches that should be further evaluated for stability, it failed to disaggregate unstable stream reaches. Limitations included not considering the streambank’s cohesion and the difficulty in assessing some metrics. The OSEPI, which included parameters to account for the streambank’s cohesion and stream curvature, had higher correlation (R2 = 0.29 for all reaches; R2 = 0.45 for reaches with similar soils) with recent streambank erosion. These results indicate promise for its use in prioritizing reaches for future stabilization projects in the Ozark region of Oklahoma. Additional research is needed to further test the generic and ecoregion-specific RGAs and to determine the conditions that necessitate ecoregion-specific indices