Journal #4 Why are river system constantly changing? The narrow depression that a stream follows downhill is called its _________. What causes the formation of a stream?

Stream Load A 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 Load Suspended 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 Discharge The 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 Gradient The velocity (speed) of a stream depends mainly on the gradient. The gradient is the change in elevation The 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 Channels As 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 Channels As a river evolves, it may develop curves and bends

Meandering Channels A 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 meanders A 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 diagram Add the following labels: (10 points each) Mouth Headwaters Meander Braided stream River Coloring is worth 50 points Total this diagram will be worth 200 points!!!!