Section 13.1Streams and Rivers

____________ – a stream and all its tributaries ________ – a smaller stream that empties into a larger

stream ______ – a high point that separates river systems _________ – the land area drained by a river system

Important Definitions!

River System

Tributary

DivideWatershed

3 factors that determine a streams velocity:

gradient discharge channel shape

Characteristics of Streams and Rivers

how steep or flat a river is steeper the gradient, the faster the river

will flow

Gradient

the amount of water that passes by a certain point in a given amount of time

varies depending on the time of year and the weather conditions

Discharge

path that makes up a river velocity of a river depends on the

depth of the channel and how winding it is

Channel Shape

Section 13.2Stream Erosion and

Deposition

Velocity and discharge affect how much material a river can transport. When river velocity greatly decreases, sediment drops out of the water to form a delta or alluvial fan.

Stream Erosion and Deposition

Over time, sediments build up, forming a delta.

Stream Weathering and Erosion

Depositionprocess by which the material is

deposited

Erosion

PotholeDeep circular

basin developed when the river develops small whirlpools

Pothole

Transporting Material

LoadDownstreamEroded rock and soilBy action of the river

SuspensionMuddy lookingClay, silt, and fine sandBetween the water molecules

Bed LoadRock transport

Stream Load/Suspension

Stream Competency vs. Capacity

CapacityTotal amount of sediment the stream

can carryCompetency

Maximum size of particle the stream can carry

Stream Deposition

Increase velocity more movement

Decrease velocity more deposition

Everything held by the water will be deposited

Delta

Fine sedimentRiver slows

down to a body of water

13.3

River Valleys

Headward Expansion

Land is worn away at the head of a river/stream

Canyon and V-Shaped Valleys

Progression

Base Level

Level to which the stream can go down

Set by the body of water the stream enters

Waterfalls

Differential erosion Hard topSoft under-strata

Section 13.4Floodplains and Floods

What is a flood? river or stream overflows its banks

What is a floodplan? area along a river that is most susceptible to

flooding

Flood Prevention

Restoring natural plant life in areas along rivers

Dams can help to control the amount of water moving downstream

Artificial levees such as sandbags can be put into place as a temporary solution

Maintain safe floodplains by not allowing people to develop the land in a floodplain