Erosion Protection & Bridge Scour Studies

Rio-Chama-near-Chama-NM-Cumbres-Toltec-Railroad-Bridge-Scour-StudyThe force of flowing water creates “scour” which is the erosion or removal of streambed or bank material. A streambank may be washing away due to scour, just as a bridge over a river can be undermined by scour. Riverbend Engineering uses hydraulic engineering methods to estimate what the effects of scour will be in a major flood event. We use the principals of fluvial geomorphology to design interventions that will reduce the potential scour impacts on bridge abutments and river banks. Traditional engineering solutions often involve heavy armoring of river banks and bridge abutments, which can be a costly endeavor. Riverbend has successfully designed scour reduction/erosion protection projects where we use simple hydraulic structures to move the scour forces away from the location we want to protect. As with any type of erosion protection, the key to success is picking the right methodology for the magnitude of the problem, and then implementing the solution at an appropriate scale. Scroll below or use the menu to the right to read more about our erosion protection and bridge scour study projects.

Santa Fe River in Santa Fe, NM -- City of Santa Fe

Cross Vane Repair

Riverbend Engineering teamed with another consulting firm on the design and construction oversight of this project for the City of Santa Fe.  Recent flood events had torn apart a cross vane structure at a sharp bend in the river, and lateral riverbank erosion had begun.  Riverbend’s design solution included armoring the outside bank of the river at the bend, widening the active channel to match the river upstream and downstream, and constructing several grade control structures to limit further channel bed erosion.  Riverbend’s design sought to fix the erosion and grade control problems with a natural looking approach, and limited the hardscape to only those areas where it was necessary.  The design palette utilized large boulders where needed, concrete grout for the largest grade control, willow and cottonwood transplants, and selected grading to shape the channel’s width and profile.  The photo below shows the largest of the grade control structures during the construction process.  As the vegetation matures, a mix of rocks and willows along the river bank looks much more natural than a continuous lining of concrete or riprap rock.

Uncompahgre River in Ridgway, CO

Ridgway logoThis project included complete river restoration, addressing decades of in-stream gravel mining. Restoration work included grading of a stable single thread channel, bank stabilization with large woody debris and large boulders, grade control and fish habitat structures, construction of multiple wetlands (open water and shallow depression types), and construction of two whitewater wave features. A new pedestrian trail was designed, extending from an existing Town park all the way north through the restored river section. The restoration work terminates at the north end at an historic railroad bridge. The design had to accommodate a new pedestrian bridge, an existing CDOT bridge, an existing sanitary sewer crossing the river, fish passage throughout, nesting bald eagle habitat, and a very high sediment load from the upstream watershed. Analysis and documentation of changes to the regulatory floodplain were prepared for FEMA map revisions. Aerial photo “Before” shows highly braided river system after in-stream gravel mining in the 1970s through 1990s. Low angle aerial image “After” shows the restored river with open water wetlands in right foreground, depression wetlands (dark brown areas) further downriver, a CDOT bridge and two whitewater wave features in the foreground. Bald eagle habitat is protected on river-right in the downstream (background) part of the project.

Rio Chama near Chama, NM – Cumbres & Toltec

cumbres toltec logoThe scope of work addressed stabilization of an eroding riverbank, threatening the south abutment of an historic railroad bridge. Riverbend designed the bank stabilization with large boulders. Riverbend handled the 404 and 401 permitting for the Cumbres & Toltec Railroad, and Riverbend directed the installation of the bank stabilization measures. Riverbend has also worked with the Cumbres & Toltec Railroad on the design of new railroad track at the Chama Depot, including rail extensions across the state highway.