Channel Patterns Straight Occurs over short reaches not

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Channel Patterns • Straight: Occurs over short reaches; not very common; sinuosity < 1.

Channel Patterns • Straight: Occurs over short reaches; not very common; sinuosity < 1. 5 • Meandering: Most commonly observed pattern; Single channel system with a sinuosity > 1. 5 • Multichannel Systems – Braided: mobile bed, banks, and bars. – Anabranching (includes anastomosing channels); multiple channels separated by vegetated floodplain materials; generally consists of stable banks, and associated with avulsion.

Straight Channel Pool Riffle Bar Thalweg Channel Banks Bar Pool

Straight Channel Pool Riffle Bar Thalweg Channel Banks Bar Pool

Flow Patterns From Ritter et al. , 1995

Flow Patterns From Ritter et al. , 1995

Velocity Reversals From Ritter et al. , 1995

Velocity Reversals From Ritter et al. , 1995

Meandering Channels T - thalweg B- bar R - riffle P - pool From

Meandering Channels T - thalweg B- bar R - riffle P - pool From Ritter et al. , 1995

Flow Patterns - Historic Model No Secondary Flow at Riffle Helical Flow From Ritter

Flow Patterns - Historic Model No Secondary Flow at Riffle Helical Flow From Ritter et al. , 1995

Flow Patterns - Current Model From Ritter et al. , 1995

Flow Patterns - Current Model From Ritter et al. , 1995

Meander Geometry From Ritter et al. , 1995

Meander Geometry From Ritter et al. , 1995

Controls on Meander Geometry From Ritter et al. , 1995

Controls on Meander Geometry From Ritter et al. , 1995

Braided Channels (Central Bar Theory - Leopold and Wolman, 1957) From Ritter et al.

Braided Channels (Central Bar Theory - Leopold and Wolman, 1957) From Ritter et al. , 1995

Braided Channels (Stalled Lingoid Dunes) From Ritter et al. , 1995

Braided Channels (Stalled Lingoid Dunes) From Ritter et al. , 1995

Parameters Influencing Braid-Bar Formation • Erodible Banks: Required for development of braided channel. •

Parameters Influencing Braid-Bar Formation • Erodible Banks: Required for development of braided channel. • Sediment Transport and Abundant Load: Most carry large amounts of sediment; not overloaded; can be incising. • Rapid and Frequent Variations in Discharge: Not an absolute requirement, but may facilitate bar formation.

Pattern Classification After Schumm, 1981

Pattern Classification After Schumm, 1981

Channel Pattern Thresholds From Schumm, 1977

Channel Pattern Thresholds From Schumm, 1977

Anabranching Channels (Associated with the Following) • Channel aggradation • stable, cohesive banks that

Anabranching Channels (Associated with the Following) • Channel aggradation • stable, cohesive banks that limit channel widening • a flood-prone hydrologic regime

Types of Anabranching Systems From Nanson and Knighton, 1996

Types of Anabranching Systems From Nanson and Knighton, 1996

Flow Diagram of Controlling Factors From Ritter et al. , 1995

Flow Diagram of Controlling Factors From Ritter et al. , 1995

River Metamorphosis (After Schumm) • • From Ritter et al. , 1995 Qw -

River Metamorphosis (After Schumm) • • From Ritter et al. , 1995 Qw - mean annual discharge or mean annual flood Qt - percentage of total load as bed material load w - channel width d - channel depth S - channel slope P - sinuosity F - width to depth ratio L - meander wavelength