streamsand

Streamsand is a term used in geomorphology to describe the sand fraction associated with river and stream systems. It refers to sand grains carried in suspension, along the bed, or deposited in sedimentary features within a channel. The term is not a brand or product, but a descriptive label for sedimentary processes in fluvial environments.

Composition and characteristics: Streamsand typically consists largely of quartz grains, with common inclusions of feldspar and lithic fragments. Particle sizes range from about 0.0625 to 2 millimeters in diameter. Sorting and rounding are influenced by flow strength, sediment supply, and river history.

Transport and deposition: Sand is mobilized by turbulence and shear in the water column and on the bed. It can move as bedload, roll or skip along the channel bed, or be carried in suspension during higher flows. Depositional features include point bars, mid-channel bars, and dune-like bedforms.

Occurrence and significance: Streamsand is found in most alluvial rivers worldwide. It supplies construction aggregates in some regions and contributes to the habitat structure of stream ecosystems. Excessive sedimentation can alter channel form and reduce hydraulic capacity, while sediment-starved rivers may experience increased incision.

Research and management: Scientists study streamsand through field sampling, particle size analysis, and hydrodynamic modelling to understand sediment transport and pooling. River restoration and dam operations affect sand budgets, influencing erosion, downstream sediment supply, and ecological health.