Journal #4Why are river system constantly

changing?The narrow depression that a

stream follows downhill is called its _________.

What causes the formation of a stream?

Today, we will describe the parts of a river system.

Stream LoadA stream transports soil, loose rock,

fragments and dissolved minerals as it flows downhill.

The materials carried by a stream are called stream load.

Stream load takes 3 forms:

Stream LoadSuspended load- consists of particles and find sand and silt. The speed of the water keeps the particles suspended.

Bed load- consists of larger, coarser materials such as pebbles. Material moves by sliding and jumping along bed.

Dissolved Load- a mineral matter transported in liquid solution.

Stream DischargeThe volume of water moved by a stream in a

given time period is the stream’s discharge.The faster the stream flows, the higher its

discharge.A fast flowing stream carries more sediment

and larger particles than a slow stream.Fast streams erode their channels more

quickly than slower streams.

Stream GradientThe velocity (speed) of a stream depends

mainly on the gradient.The gradient is the change in elevationThe beginning of the stream is called

“headwaters”.Here, the speed is high because it is usually

steep.The mouth of the stream is where the stream

enters a large body of water. The gradient becomes flatter here and the

speed slows.

Evolution of River ChannelsAs the stream’s load, discharge and gradient

decrease, the erosive power of the stream decreases.

Over time, the channel erodes and becomes wider and deeper

When the stream becomes longer and wider, it is called a river.

Meandering ChannelsAs a river evolves, it may develop curves and

bends

Meandering ChannelsA river that has a low gradient tends to have more

bends than a river that has a steep gradient does.Wide curves in a river are called meandersA winding patterns of these meanders develop

because as the gradient decreases, the velocity of the water decreases.

Therefore, the river is less able to erode down onto its bed.

The outside curves on a river are faster moving than the inside of the curves which causes deposition of sand and gravel. Page 381

Braided Streams Most rivers are simple channels.However some rivers divide into multiple

channels (page 382)A stream or river that is composed of

multiple channels that divide and rejoin around sediment is called a braided stream

Braided streams are the result of a large sediment load

Although braided streams look very different from meandering channels, they can cause just as much erosion.

Let’s Review:What are tributaries?

What is a watershed?

What happens in a suspended stream load?

The volume of water moved by a stream in a give time is the stream’s _________.

What is the stream’s gradient?

What are meanders?

What are braided streams?

Your assignment:Complete the river diagramAdd the following labels: (10 points each)

MouthHeadwatersMeanderBraided streamRiver

Coloring is worth 50 pointsTotal this diagram will be worth 200

points!!!!