Cut bank erosion and point bar deposition as seen on the Powder River in Montana.Cut banks along the Cut Bank Creek
A cut bank, also known as a river cliff or river-cut cliff, is the outside bank of a curve (meander) in a water channel (stream), which is continually undergoing erosion.[1] Cut banks occur on the outer side of meander bends, opposite the point bar or slip-off slope on the inner side.[2] They are shaped much like a small cliff, and are formed as the stream collides with the river bank.[3] It is the opposite of a point bar, which is an area of deposition of material eroded upstream in a cut bank.[4]
Typically, cut banks are steep and may be nearly vertical.[5][6] Erosion can undercut a cut bank and cause masses of bank material, trees, and vegetation to collapse or slide into the river; flooding and bank erosion can also damage nearby property and structures.[7][8]
Given enough time, the combination of erosion along cut banks and deposition along point bars can lead to the formation of an oxbow lake.[4]
Not only are cut banks steep and unstable, they are also the area of a stream where the water is flowing the fastest and often deeper.[9] The greater velocity and energy of flow along the outer bend produces erosion of the cut bank.[10]
A large meander on the Economy River. The cut bank is the near-vertical cliff on the outside of the meander.Close-up view of a cut-bank on the Economy River, showing its steepness