Streams

(,rivers, brooks, creeks, etc.)

Processes

• Erosion • Deposition

Loads

• Bed load– gravel– rounder with greater working

• Suspended load– silt

• Dissolved load– salt, lime

Load Carrying Capacity

• Higher velocity flow allow stream to carry:– larger particles– more total load per volume

What Happens When

• Deposition when flow slows• New erosion when flow speeds up

Sorting

• Velocity changes gradually• Slowing: deposit heaviest load• Speeding: remove lightest substrate• Result: particles of same size found

together (sorted)

Common Profile

• Steep and fast in headwaters• Slower near base• Cannot excavate below base level

Drainage Patterns

Determined by substrate characteristics

Dendritic Trellis Radial

Stream Features

Headlands

• V-shaped valleys• Erosion dominates• Alluvial fan at foot of mountain

Bottomlands

• Flat valleys• Deposition dominates• BUT—flow is variable

Bottomland Features

• Floodplains• Meanders• Oxbows• Levees• Yazoo streams

Meanders

• Erosion on outside• cut bank

• Deposition on inside• point bar

• cutoffs• Oxbows

Meandering River

Meander Evolution

Meander Evolution

Meander Evolution

Meander Evolution

Meander Evolution

Meander Evolution

Meander Evolution

Meander cutoff

Oxbow lake

Floods

• Normal• Bank-full discharge ~ 2 years• Deposit on levees, flood plains

Meandering river flooding

Base Level

• Delta: deposits• choke with sediment• many distributary channels• lobes shift• old sediments subside