Investigating Stream Rehabilitation Methods at Stroubles Creek

1. Investigating Stream Rehabilitation Methods at Stroubles Creek Matthew Gloe, Tess Wynn, Cully Hession Biological Systems Engineering, Virginia Tech, Blacksburg, VA Measuring Success The project will be monitored for the first three years following construction to ensure maintenance and success of the bank stabilization treatments and riparian buffer vegetation. Success for the riparian buffer and varying restoration techniques will be based on the following factors: 1) Successful vegetation establishment 2) Channel stability Successful vegetation establishment is defined as 75% cover of non-invasive species after three growing seasons. Channel stability will be quantified through repeat surveying of channel morphology to evaluate lateral channel migration, changes in planform geometry, and changes in erosion/deposition dynamics. Abstract Stroubles Creek, located in southwest Virginia, is the main stream draining Blacksburg and Virginia Tech. An 8 km section downstream of Virginia Tech’s Duck Pond was listed on the 303(d) list for violating benthic standards in 1998. The impairments most likely stem from the direct access of cattle to the stream, upstream construction, the incised channel, and resultant failing banks. Due to these impairments, a restoration plan was developed for 2 of the 8 km and funded by Virginia Department of Recreation – Division of Soil and Water Conservation (DCR-DSWC). The main goal of the plan was to improve aquatic habitat, reduce sediment loading from eroding banks, and reduce bacterial impairments from cattle. The restoration site location is shown in Figure 1. The restoration project will be utilized for future undergraduate- and graduate-level education at Virginia Tech.In addition, an outreach program on stream function and restoration will be developed to highlight the project. Bank Reshaping and Replanting Cattle Exclusion Only Fall Construction This past fall, implementation of the restoration plan commenced. Volunteers made up the bulk of the work force, and over half of the planned construction was completed. Cattle were excluded from all reaches, and the bank regrading and replanting was accomplished. The majority of the natural channel design sections were constructed on the main stem of Stroubles, leaving three bank sections to finish in the spring. In addition, relic ditches which drained floodplain wetlands were plugged. Highly variable weather ultimately limited the access of heavy equipment to the lower stream reaches (saturated floodplain and wetlands) and forced an early shut down of construction. In conjunction with the fall construction, numerous tours and classes were held at the restoration site. Students utilizing the site as an outdoor lab were educated about stream restorations and wetlands. Natural Channel Design Virginia Tech Figure 2. Experimental reaches of Stroubles Creek Continuation and Spring Construction Construction at the restoration site will resume this spring. The final few natural channel design sections will be established, and work will begin on the tributary feeding Stroubles Creek. Individuals and volunteer groups are encouraged to participate in the effort. Please visit www.stroublescreek.bse.vt.edu/restoration to learn how to volunteer, learn more about the project, and view any important updates regarding the project. Figure 1. Stroubles Creek restoration site location Figure 3. Regrading stream banks and placing coir logs Figure 4. Volunteers sewing coir logs and mats together Experimental Design Our restoration plan includes three alternative restoration techniques which will be evaluated and compared: 1) livestock exclusion only; 2) livestock exclusion with grading of vertical banks to 3:1 and planting of native riparian vegetation; 3) livestock exclusion with a two-stage channel design Cattle exclusion reduces sediment, nutrient, and bacterial loading to the stream. Bank grading to a stable slope and revegetation prevents geotechnical slope failure, inherently reducing sediment loading. Revegetation and natural channel design, informed by hydraulic, sediment-transport, and bank-stability modeling, also reduces sediment loading to the stream and increases the capacity for handling floodwaters. Figure 7. Completed bank with planted riparian buffer Figure 5 & 6. Before and after. Finalized bank awaiting plants Visit www.stroublescreek.bse.vt.edu/restorationfor more information