What phenomenon describes abrupt changes in stream elevation followed by upstream migration?

The phenomenon that describes abrupt changes in stream elevation followed by upstream migration is known as headset migration. This term relates to a specific type of erosion process that occurs at the head of a channel, where a rapid drop in elevation leads to an increase in erosional forces. As a result, the upstream channel begins to erode backward toward the area of elevation drop, which can alter the stream's profile significantly over time.

In contrast, general scour refers to the process where sediments are eroded uniformly across the streambed, leading to a lowering of the bed elevation rather than abrupt changes. Aggradation involves the build-up of sediment within a stream channel, often leading to rising streambed elevation rather than the abrupt lowering associated with it. Streambank damage refers to physical deterioration of the riverbanks, which may be influenced by water velocity and sediment movement but does not specifically explain the phenomenon of elevation changes followed by upstream migration.

Understanding headset migration is essential for bridge safety inspectors, as the effects can impact bridge foundations and overall structural integrity, making it a critical concept within the scope of bridge inspections and maintenance.