Stream - A body of running water that is confined in a channel and moves downhill under the influence of gravity. A flood occurs when the stream fills and leaves its channel.

Channel - A long narrow depression eroded by the stream into rock or sediment.

Flood plain - A broad strip of land built up by sedimentation on either side of a stream channel.

Sheetwash - A thin layer of unchanneled water flowing downhill.

Discharge - The amount of volume of water that flows past a given point in a unit time.

Gradient - Downhill slope of the stream bed. Changes in gradient can cause deposition and erosion.

Runoff - The average annual rainfall on the area of the United States is equivalent to a layer of water 76 cm thick covering this same land surface. Of this layer, 45 cm returns to the atmosphere by evaporation and transpiration and 1 cm infiltrates the ground; the remaining 30 cm forms runoff, the portion of precipitation that flows over the land surface.

Base level - The limiting level below which a stream can not erode the land. As a stream flows downslope, its potential energy decreases and finally falls to zero as it reached the sea.

Types of Channels:

Meandering Channels - a channel which forms a series of smooth bends that are similar in size and resemble in shape the switch backs of a mountain road.

Meander cutoff - a new shorter channel across the narrow neck of a meander. Nearly 600 km of the Mississippi River channel has been abandoned since 1776 by meander cutoff. However, the river has not been shortened appreciably because the loss of channel due to cutoffs has been balanced by lengthening of the channel as other meanders have enlarged.

Oxbow lake - a lake within a cutoff meander.

Braided Channels - A stream which has lost its main channel by the deposition of bars. Usually such streams are heavily loaded. The stream widens continuously as more bars are deposited.

Stream's Load - Sediment load transported by a stream can be subdivided into bed load, suspended load, and dissolved load.

Bed Load - Heavy or large sediment particles that travel near or on the stream bed. These particles are either sand or gravel and they move by saltation (a series of short leaps or bounces of the bottom).

Suspended Load - Sediment that is light enough to remain lifted indefinitely above the bottom by water turbulence.

Dissolved Load - Soluble products of chemical weathering.

Stream Deposits:

Bar - a ridge of sediment, usually sand or gravel, deposited in the middle or along the banks of a stream.

Flood plain - part of a stream valley which is inundated by floodwater.

Levee - a broad, low ridge of fine alluvium build along the side of a channel by debris -laden flood water.

Terraces - the remnant of abandoned flood plains.

Alluvial Fan - a fan-shaped body of alluvium typically built where a stream leaves a steep mountain valley.

Deltas - a sedimentary deposit that forms where a stream flows into standing water and so-named because it may develop a crudely triangular shape that resembles the Greek letter delta.

Stream Patterns: - A tributary is a smaller stream joining the main stream at an acute angle. The nature by which tributaries join main streams determines the drainage pattern.

Dendritic - irregular branching of channels in many directions.

Trellised - Rectangular arrangement of channels in which principal tributary streams are parallel and very long.

Parallel - Parallel or subparallel channels that have formed on sloping surfaces underlain by homogeneous rocks.

Radial - channels radiate out, like the spokes of a wheel from a topographically high area.

Rectangular - channel system marked by right-angel bends.