Response of Channel Morphology and Riparian Vegetation Following Restoration and Land Use Changes, Adobe Creek, California

Abstract

The effects of restoration efforts and land-use change on the channel morphology and riparian vegetation of Adobe Creek, California, are examined. The landowners put 667 hectares (1,649 acres) of private land on Adobe Creek into a conservation easement under the Natural Resources Conservation Service’s (NRCS) Wetland Reserve Program (WRP). The establishment of Adobe Creek WRP includes physical restoration and land use changes for the stream and surrounding areas previously affected by agricultural practices, such as grazing, an agricultura ldam, and irrigation of pastureland. My hypothesis for this project is: With the absence of cattle grazing, reduction in irrigation, and physical restoration of Adobe Creek WRP, stream channel morphology and riparian vegetation will change, specifically with narrowing bankfull widths and increased riparian vegetation. To evaluate changes on Adobe Creek, I used stream cross-sections, satellite imagery, and photo comparisons. I followed the USDA Forest Service methodology (Harrelson et al. 1994) using a laser-level to survey the cross-sections, noting channel morphology. I analyzed satellite images from the creation of the WRP up to 2022 and used available past photos to compare to 2024. My results indicate that restoration efforts and land use change led to increased woody riparian vegetation and changes in channel morphology. The bankfull widths of three of the four active cross-sections narrowed and decreased in cross-sectional area, with one cross-section showing the opposite effect. All the photo comparisons indicate substantial growth of Salix spp. (willow) along the stream channel. The restoration performed on Adobe Creek as part of the Wetland Reserve Program appears to have enhanced the stream and riparian ecosystems. While not conclusive, the result of this study indicates that changes occurred in the channel morphology and riparian vegetation of Adobe Creek following restoration activities, absence of cattle grazing, and reduced irrigation, concurrent with my hypothesis. My findings underscore the importance of tailored restoration strategies and long-term monitoring to sustain healthy stream ecosystems.