R IVERS Research Review

F ACTORS THAT A FFECT R IVER V OLUME 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 runoff = > volume

F ACTORS A FFECTING R IVER V ELOCITY 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

W AYS A R IVER CAN E RODE 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

H OW R IVER ’ S T RANSPORT A L OAD 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)

U PPER C OURSE River Channel Small and narrow Rough and shallow < volume < speed River Valley Deep, narrow, and steep-sided V shaped valley

U PPER C OURSE F EATURES 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

M IDDLE C OURSE River Channel Wider and deeper > volume < gradient than upper course River Valley More open U shaped Wider river floor

M EANDERS 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

L OWER C OURSE River Channel Deepest and widest Greatest volume Lowest speed Gentle gradient River Valley broad Flat Bounded by bluffs

L OWER C OURSE F EATURES 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