RIVERSResearch Review

FACTORS THAT AFFECT RIVER VOLUME Size of Drainage Basin

large drainage basin= several tributaries= more volume

Vegetation heavy vegetation= < runoff= < volume Little vegetation= > runoff= > volume

Climate > precip= > volume < precip= < volume

Permeability of Rock > permeability = < runoff = < volume < permeability = > runoff = > volume

FACTORS AFFECTING RIVER VELOCITY Discharge

> discharge = faster flow Gradient of the Land

Steeper river channel = faster flow Roughness of Channel

Rough river bed = slower flow Shape of Channel Cross Section

More water is in contact with riverbed = slower flow

Faster in middle than on sides

WAYS A RIVER CAN ERODE Abrasion/Corrasion

Rocks carried in the river grind/erode rocks Widens and deepens

Hydraulic Action force of the water causes rocks to break

Attrition Material suspended in water collides w/ each

other and become smoother and rounder Solution/Corrosion

Water dissolves mineral in rocks and carries it away

HOW RIVER’S TRANSPORT A LOAD Solution

Material dissolved in the water (minerals) Suspension

Light material that is suspended in the water and carried in river (sand, silt, etc.)

Saltation Gravel/small rocks lifted and carried small

distances and then dropped (related to river energy)

Traction Movement of large boulders Requires lots of river energy (flood)

UPPER COURSE River Channel

Small and narrow Rough and shallow < volume < speed

River Valley Deep, narrow, and steep-sided V shaped valley

UPPER COURSE FEATURES Rapids

Occurs between soft and hard rock Hard rock does not erode as fast as soft rock Create areas of steep slope and less steep slope

Waterfalls Sudden fall of water where water drops vertically

Plunge Pool Dent in river bed at bottom of waterfall

MIDDLE COURSE River Channel

Wider and deeper > volume < gradient than upper course

River Valley More open U shaped Wider river floor

MEANDERS Bends in river May go around tree or rock Water outside bend moves faster than inside

(more erosion outside) Sediment is deposited on inside of meander

b/c of slower velocity Deeper and more velocity outside Shallower and less velocity inside

LOWER COURSE River Channel

Deepest and widest Greatest volume Lowest speed Gentle gradient

River Valley broad Flat Bounded by bluffs

LOWER COURSE FEATURES Levees and Floodplains

Rivers slow and drop load which shallows river and flat land decreases velocity

Heavy rain causes river to overflow banks into plains

Delta Occurs at mouth of river where dumps into sea Slowing of rivers drops deposits

Ox Bow Lake Horse shoe shaped or crescent shaped Forms when deposits build on concave banks of

meander and become joined