Stream Corridor Structure: A Longitudinal View

The processes that develop the characteristic structure seen in the lateral view of a stream corridor also influence structure in the longitudinal view. Channel width and depth increase downstream due to increasing drainage area and discharge. Related structural changes also occur in the channel, floodplain, and transitional upland fringe, and in processes such as erosion and deposition. Even among different types of streams, a common sequence of structural changes is observable from headwaters to mouth.

Longitudinal Zones
The overall longitudinal profile of most streams can be roughly divided into three zones (Schumm 1977). Zone 1, or headwaters, often has the steepest gradient. Sediment erodes from slopes of the watershed and moves downstream. Zone 2, the transfer zone, receives some of the eroded material. It is usually characterized by wide floodplains and meandering channel patterns. The gradient flattens in Zone 3, the primary depositional zone. Though the figure displays headwaters as mountain streams, these general patterns and changes are also often applicable to watersheds with relatively small topographic relief from the headwaters to mouth. It is important to note that erosion, transfer, and deposition occur in all zones, but the zone concept focuses on the most dominant process. You can view a full-screen depiction of how several flow, channel size, and sediment characteristics change throughout the three longitudinal zones.