Understand how running water

acts as an agent of erosion and

deposition. (Chapter 2)

Tributaries are branches of a river that feed water into the larger river

Rivers flow from high elevation to low elevation

Rivers empty into the sea at sea level = 0 m

Look for elevation legend, often color coded, symbols or contour lines.

What direction does the river flow? Where is the high elevation?

Where are the tributaries?

Where does the river begin?

Drainage Basin = the area of land drained by a river and its tributaries.

Try question #4 p. 26

The Amazon Basin is the planet's largest body of fresh water with 1100 tributaries 17 of which are more than 1000 miles long.

Many of the tributaries begin in Colombia and Peru.

WHY????

The Nile river in Africa is the longest river in the world.

The green area on the map marks the Nile River basin.

Rivers change over time and seem to go through stages:

V-shaped and narrow with steeper sides

Vertical erosion (bottom of the river)

Low water volume, but faster flows

Higher gradient (slope)

Rapids and/or waterfalls are common

Usually found in highland or mountain regions

Rapids

and low

water

volume

Steep sides

Most high relief is eroded

Gentler slope

Many well developed tributaries

Broad flat river valley

Well developed flood plain

More lateral (↔) erosion than vertical

Meandering results

Higher water volume, but slower flow

Slower flow, but higher volume Sides that are less steep

Remember the stages are not distinct.

These changes occur over long periods of time.

Meanders

form

Almost no slope Very little relief Elaborate

meandering Often swampy areas

around river Very muddy due to

slow speed and deposition

Most susceptible to flooding because of large flood plain.

Oxbow lakes develop

Meanders

Oxbow Lakes

http://www.kented.org.uk/ngfl/subjects/geography/rivers/River%20Articles/oxbowlake.htm

http://www.youtube.com/watch?v=ef1HI3MoXFs&feature=related

Vertical erosion makes rivers deeper as is the case in young rivers

Lateral erosion makes rivers wider leading to the meandering of mature rivers.

Youth Stage

Mature Stage

Old Age Stage

Delta = low lying area at

mouth of river formed by

deposition of silt deposition occurs

because river slows as it enters ocean or lake

Arcuate Delta=

Named from Latin word for curved in the shape of a bow.

Fan shaped

Example Nile Delta p. 32

Nile

Delta

Digitate Delta =

From Latin for finger

Delta with long fingers of sediment reaching into the sea

Example Mississippi

Mississippi

Delta

Estuarine Delta =

Formed when river runs into bay or estuary

Tidal mud flats form which can be seen at low tide

Sediment deposited from river outflow and from Tidal inflow

Sacramento River – San Joaquin

San Francisco Bay Delta

Similarities Arcuate & digitate

both flow into open ocean

All three allow river water to flow out

All have channels or distributaries cut into them by the river

Differences Estuarine empties

into a bay whereas other 2 empty into open water

Three different shapes

1. Slope of the river 2. Relief of the

banks 3. Width of the

valley 4. Meandering 5. Size of flood

plain 6. Rapids or water

falls

Evidence to look for!!

Young

Water falls & rapids

Steep slope

Late maturity

Meandering

Flood plain developing

Youth

Rapid water movement

Rapids & water falls

High relief on banks