These streams are eroding by scour and bank failure. The cohesive sediments are more scour resistant than the sandy sediments.
Bank failure is of the slab type, and is a normal part of the erosion process.
The purpose of this study was to survey the areal distribution of streambank failures and eroded reaches in an urban setting and to identify those variables associated with each mode of bank failure and channel shape. Identification and mapping of streambank sediments and failure modes were a major part of the research. The study provides baseline data regarding the spatial distribution of bank failures and associated sediments. Suggestions Regarding Channelization Procedures Channelization in the Piedmont region of the United States, and similar areas, should avoid cutting into mechanically deposited fills or creating such fills in the lower banks. Slope instability and scour can be greatly hindered, without structural protection or with only minor, selectively placed protection, by constructing a berm about one-third bank height for channels deeper than six feet.