Stream Processes

Oxbow Lake

A crescent shaped meander with the outer edge cut off by new channels cut during floods.

Rectangular Pattern

A network of channels with right angle bends that form a pattern of interconnected rectangles and squares. Often develops over rocks that are fractured or faulted in two main directions that are perpendicular and break the bedrock into rectangular or square blocks. The streams erode channels along the perpendicular fractures and faults.

Deranged Pattern

A random pattern of stream channels that seem to have no relationship to underlying rock types of geological structures.

Delta

A sediment load dropped by a stream, which accumulated as a triangular or fan-shaped deposit in a lake or ocean.

Annular Pattern

A set of incomplete, concentric rings of streams connected by short radical channels. This pattern commonly develops on eroding structural domes and colds that contain alternating folded layers of resistant and nonresistant rock types.

Head

A stream's point of origin, may be at a spring of at the start of narrow runoff channels developed during rainstorms.

Yazoo Tributary

A tributary that cannot breach a river's levee

Centripetal Pattern

Channels converge on a central point, often a lake of playa (dry lake bed) at the center of a closed basin (one where no water can drain because there is no outlet valley).

Meandering

Channels that become sinuous

Point Bar

Deposits that accumulate along the inner edge of meanders.

Floodplains

Develop when alluvium accumulates landward of the river banks during floods.

Stream Drainage System

Drainage network from tributaries to larger streams, to the largest rivers

Levees

Higher than the rest of the flood plain.

Channel Bars

Linear, underwater sand bars.

Braided Stream

Low gradient, high discharge streams that become overloaded with sediments can form this pattern.

Flood

Overflow the banks of streams

Stream Terraces

Remnants of older Floodplains that have been dissected.

Trellis Pattern

Resembles a vine or climbing rose bush growing on a trellis, where the main stream is long and intersected at nearly right angles by its tributaries. The pattern develops where alternating layers of resistant and nonresistant rocks have been tilted and eroded to form a series of parallel ridges and valleys. The main stream channel cuts through the ridges, and the main tributaries flow perpendicular to the main stream and along the valleys.

Dendritic Pattern

Resembles branching of trees, water flows from branch like tributaries to the trunk like main stream. Common where a stream cuts into flat lying layers of rock or sediment, or where a stream cuts into homogenous rock or sediment.

Alluvium

Sediment transported by streams, and eventually deposited

Alluvial Fan

Similar to a delta, a deposit of stream sediment that occurs where a steep gradient stream abruptly enters a wide, level plain.

Headward Erosion

Stream channels deepen and erode their v-shaped channels uphill through time

Load

The amount of material (mostly alluvium, but also plants, trash, and dissolved material) that is transported by a stream. In uplands. Most streams have relatively steep gradients, so the streams cut narrow, V-shaped valleys. Near their heads, tributaries are quick to transport their load downstream, where it combines with the loads of other tributaries. Therefore, the load of the tributaries is transferred to the larger streams and eventually, to the main river. The load is eventually deposited at the mouth of the river where it enters a lake, ocean, or dry basin.

Geology

The bedrock geology over which the stream flows affects the stream's ability to find or erode its course.

Mouth

The end of a river valley

Drainage Basin

The entire area of land that is drained by one stream, of an entire stream drainage system.

Uplands

The highest elevations in drainage basins, where the smallest valleys are.

Divides

The linear boundaries that separate one drainage basin from another.

Base Level

The lowest level to which a stream can theoretically erode. Base level is achieved where a stream enters a lake or ocean. Erosion all power of the stream is zero and depositional processes occur.

Cutbanks

The outer edge of meanders.

Discharge

The rate of stream flow at a given time and location. Discharge is measured in water volume per unit of time, commonly cubic feet per second.

Gradient

The steepness of a slope, either the slope of a valley wall or the slope of s stream along a selected length of its channel. Generally expressed in feet per mile.