River bank erosion along the Nashwaak River
University of New Brunswick
River bank erosion is a naturally occurring process wherein the surface material along the edge of the water is removed, entrapped, transported, and deposited down stream. Because of recent development along the Nashwaak River, vegetation has been removed from the banks, resulting in increased river bank erosion rates. Presently permanent engineering structures including riprap and cement walls are being used to prevent erosion, but these methods are not ideal. These permanent structures allow the water to speed up in the original problem area and erode the bank further down stream creating a new problem. At the Nashwaak Village field site five different layers of sediment exist; they including overburden, fine sand, pebble, orange-brown clay, and light grey clay. The clay layers were focused on in this project because they are located where the majority of erosion occurs. Experiments indicated that these layers could experience erosion rates as high as 350 mm/day, although that was uncommon. A combination of riprap, vegetation, and boulder clusters are recommended to minimize erosion and costs and to maximize the environmental benefits of river bank protection.