Abstract: Session F 2:20 pm (Back to Session F)
15-Years of Kansas Stream Data Collection, Restoration and Stabilization Projects, A Summary of Lessons Learned
Watershed Institute, Inc./Watershed Land Trust, Inc.
For over fifteen years, staff from the Watershed Institute, Inc. (TWI) and Watershed Land Trust, Inc. (WLT) has been involved in fluvial geomorphology data collection, stream restoration, and streambank stabilization projects in Kansas. Fluvial geomorphology data collection began with Rosgen Level II morphology surveys to calibrate and develop a bankfull dimension, pattern, and profile dataset. Subsequent data collection efforts have surveyed and analyzed Rosgen Level III assessment data and identified and surveyed streambanks exhibiting high erosion potential and used the Bank Erodibility Hazard Index (BEHI) to predict sediment erosion quantities. Our observations suggest that nearly all Kansas streams are degraded due to landuse change, channelization, impoundments, and urban development. Most streams have narrowed and deepened, classifying as unstable C and E stream types with over-steepened streambanks and little to no riparian corridor. Resultantly, channel erosion is a common sediment source resulting in high stream turbidity and reservoir sedimentation, the latter a threat to many Eastern Kansas water supply allocations. Kansas has increased priority in stabilizing streambanks and TWI/WLT has been a technical service provider for streambank stabilization design and construction oversight services. TWI/WLT uses previously collected fluvial geomorphology data and current geomorphology surveys as a basis for streambank stabilization designs. Over the years, TWI/WLT has found excavating streambanks, strengthening the streambank toe, and restoring the riparian corridor to be viable applications in slowing streambank erosion. TWI/WLT has found rock vanes to be a most reliable stabilization structure as the vanes reduce water velocities and redirect flow away from the near-bank region (even with 25-feet of water overtop the structures). TWI/WLT will present project successes and failures that have guided our streambank stabilization approach. At TWI/WLT, stream restoration work is tied to U.S. Army Corps of Engineers 404 permit mitigation. TWI/WLT have found that mitigation activities such as lowhead dam or perched/undersized culvert removal are often the best ways to provide aquatic habitat lift. Here we discuss lessons learned from past stream restoration efforts and how those lessons inform our efforts moving forward.