Bank erosion is the wearing away of the banks of a stream or river. This is distinguished from erosion of the bed of the watercourse, which is referred to as scour.
The roots of trees growing by a stream are undercut by such erosion. As the roots bind the soil tightly, they form abutments which jut out over the water. These have a significant effect upon the rate and progress of the erosion.
Hangu Pass or Hanguguan was a fortified gateway that commanded the strategic mountain pass between the Yellow River and Qinling Mountains, forming the main choke point on the only land corridor between the Central Plain and the Guanzhong region. The pass restricted access into the lower Wei River valleys, where the heartland of the state of Qin and the unified Qin dynasty were located, as well as the subsequent dynasties of Han, Sui and Tang.
The Hangu Pass lies on the south (right) bank of the Yellow River, 60 km (37 mi) downstream of its eastward bend out of the Ordos Loop. It was built by the state of Qin in 330 BC and had been the site of many sieges and field battles during the Warring States period and early imperial eras. Due to terrain changes from bank erosions and alluvial deposition of the Yellow River over the centuries, the Hangu Pass eventually fell to ruins after losing its defensive values to the newer Tong Pass to its west, which was built near the mouth of the Wei River in 196 AD by the warlord Cao Cao.
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. Cut banks are found in abundance along mature or meandering streams, they are located opposite the slip-off slope on the inside of the stream meander. They are shaped much like a small cliff, and are formed as the stream collides with the river bank. It is the opposite of a point bar, which is an area of deposition of material eroded upstream in a cut bank.
Typically, cut banks are steep and may be nearly vertical. Often, particularly during periods of high rainfall and higher-than average water levels, trees and poorly placed buildings can fall into the stream due to mass wasting events. Given enough time, the combination of erosion along cut banks and deposition along point bars can lead to the formation of an oxbow lake.
Napoleon was a river port and the county seat of Desha County, Arkansas, from 1838 to 1874. It was located at the confluence of the Arkansas and the Mississippi rivers. Napoleon was badly damaged during the Civil War and then finally abandoned after most of it had washed into the Mississippi River.
River channel migration is the geomorphological process that involves the lateral migration of an alluvial river channel across its floodplain. This process is mainly driven by the combination of bank erosion of and point bar deposition over time. When referring to river channel migration, it is typically in reference to meandering streams. In braided streams, channel change is driven by sediment transport.
It has been proposed that lateral migration is a particularly dominant erosive process in savanna landscapes.