Streams and Rivers Terms

Lotic

Freshwater system or waterbody characterized by moving water, e.g., streams and rivers.

Lentic

Freshwater system or waterbody characterized by non-moving or flowing water, e.g., lakes & ponds

Watershed

Topographic area of land draining to a single point via surface or groundwater flow

River Basin

The watershed and all of the contributing waterbodies of a specified major river

Discharge

Volume of water that flows through a stream at any given point of time

Thalweg

Main river channel, can be thought of as a line running the length of the stream connecting lowest (deepest) points of the river channel; typically where most of the flow is occurring

Strahler Stream Order

A top-down dendritic classification of river systems to identify a hierarchy of tributaries within the system; 1st order streams have no streams flowing into them, 2nd order streams originate at the intersection of two 1st order streams, 3rd order streams originate at the intersection of two 2nd order streams, and so on; small headwater streams are 1st order, the Mississippi River is 10th order, and the Amazon is a 12th order stream

Riffle

Habitat in smaller rivers and streams with shallow, fast-moving water close to the substrate, where the water surface is turbulent or broken

Shoal

Area of shallow water created from a rock outcrop, gravel, or sand; can create riffles

Run

Moderately fast-moving riverine habitat where the water surface is not turbulent or is unbroken; runs often have laminar flow

Pool

Deeper and generally slower habitat within a stream or river

Riparian Area

Terrestrial vegetation along a stream or river within the floodplain; contributes allochthonous material, bank stability, erosion control, and shading to a river

Backwater

Habitat in a river consisting of slow current caused by an upstream obstruction (e.g., boulder, streambank, woody debris); backwater habitats may be deep (pools) or shallow

River Continuum Concept

Model for classifying and describing riverine ecosystems; states that a river is dependent on upstream inputs and that biotic complexity increases as the river grows in size, often resulting in greater diversity and productivity downstream

Allochthonous Material

Biomass and nutrients generated outside of the river, within the watershed

Autochthonous Material

Biomass and nutrients generated from productivity within the river