Chapter 11

Stream Drainage Pattern

Arrangement of stream channels and tributaries that forms on a landscape as a result of its underlying geology and relief.

Levees

Higher parts of a floodplain that develop in cases of minor flooding events that deposit sediment only where the water barely overflows the river's banks.

Dendritic Pattern

Irregular pattern of channels that branch like a tree; develops on flat lying or homogeneous rock.

Divides

Linear boundaries that separate one drainage basin from another.

Sinuosity

Measure of how much a stream channel meanders side-to-side; "how bendy" a stream channel is.

Escarpments

Steep slopes or cliffs separating the relatively horizontal stream terraces.

Head

Stream's point of origin; may be a spring or at the start of a narrow runoff channels developed during rainstorms.

Centripetal Pattern

Channels converge on the lowest point in a closed basin from which water cannot drain.

Deranged Pattern

Channels flow randomly with no relation to underlying rock types or structures.

Rectangular Pattern

Channels have right-angle bends developed along perpendicular sets of rock fractures or joints.

Radial Pattern

Channels radiate outward like spokes of a wheel from a high point.

Point Bar

Deposits that accumulate along the inner edge of meanders.

Oxbow Lake

Develops as a result of the development of channels that cut new paths during floods; a cut off piece of the outer edge of a meander; crescent-shaped.

Floodplains

Develops when a stream's load may exceed the water's ability to carry it, so the solid particles accumulate as sedimentary deposits along the river margins/banks; when alluvium accumulates landward of the river banks.

Mass Wastage

Downslope movement of Earth materials such as soil, rock, and other debris.

Mouth

End of a river valley; where a stream enters an outlet waterbody or a dry basin.

Drainage Basin

Entire area of land that is drained by one stream or an entire stream drainage system.

Stream Drainage System

Entire drainage network, from the smallest upland tributaries to larger streams, to the largest river (main stream or main river).

Headward Erosion

Erosion that causes stream channels to deepen and their V-shaped channels uphill through time.

Alluvial Fan

Fan-shaped deposit of stream sediment occurring where a steep-gradient stream abruptly enter a wide, dry plain.

Yazoo Tributary

Formed by a tributary's inability to breach a river's levee; flows parallel to the river.

Delta

Forms when a stream enters an outer waterbody; velocity decreases; stream drops its sediment load, which accumulates as a triangular/fan-shaped deposit.

Braided Stream

Forms when low gradient/high discharge streams become overloaded with sediment.

Channel Bars

Linear, underwater sandbars in a braided stream.

Annular Pattern

Long channels form a pattern of concentric circles connected by short radial channels; develops on eroded domes or folds with resistant and nonresistant rock types.

Base Level

Lowest level to which a stream can theoretically erode.

Meandering

More prevalent as gradient decreases and more as discharge and load increase; very wide and flat floodplains with sinuous channels.

Discharge

Rate of stream flow at a given time and location; measured in water volume per unit of time.

Uplands

Smallest valleys in a drainage basin occur at high elevations; stream's point of origin.

Stream Terraces

Surfaces that are higher than the present floodplain; remnants of older floodplains that have been dissected (cut by younger streams).

Flood Stage

Water level exceeds the river banks.

Bankfull Stage

Water level is even with the banks.

Normal Stage

Water level of a river is below the river's banks.

Load

Amount of material that is transported by a stream.

Trellis Pattern

A pattern of channels resembling a vine growing on a trellis; develops where tilted layers of resistant and nonresistant rock form parallel ridges and valleys; the main stream channel cuts through the ridges, and the main tributaries flow along the valleys parallel to the ridges and at right angles to the main stream.

Tributaries

A smaller stream that feeds into a larger stream.

Cutbanks

Outer edge of meanders; where erosion occurs.