How does a river change as you travel downstream

(The long Profile of a river)

A rivers long profile looks something like this:

Upper Course

Middle Course

Lower Course

Is it upper, middle or lower?

What are the differences between a river in its upper, lower , middle ?

Question? How does a river change as you travel downstream?

What changes can you think of?

Key river terms

1. Load = The amount of material being carried

by a river

2. Velocity = the speed of a river in metres per second m/s

Key river terms cont…

3. Discharge = is the amount of water passing a

given place at a given time

Discharge = velocity x cross sectional area ( speed) (depth and width)

m³/ s = m/s x m²

• Velocity (speed) = • Discharge = • Width and depth = (e.g Increases / decreases downstream)

• Load carried =

(Copy the table from Wider World p285- as you do this be thinking ‘Why do the following change as you move downstream?’)

The main changes in the river channel are as follows:

Why do rivers change from the upper to the lower

course?

Its all about energy ……..

Turn to page 282 in Waugh and read the 1st 2 paragraphs. Decide on the most important points

Friction ( a river looses 95% of its energy due to friction)

Which channel has most friction?

explanation..

Lower Course Channel

Upper Course Channel

Lower Course Channel

Wetted perimeter

Velocity (speed)

Which channel will have the fastest velocity? Why? Lower Course Channel

Upper Course Channel

Lower Course Channel

explanation..

Energy and Power

Which channel has most power and spare energy? Why? Lower Course Channel

Upper Course Channel

Lower Course Channel

explanation..

Erosion

The spare energy is used to erode deeper and wider Lower Course Channel

Upper Course Channel

Lower Course Channel

Erosion

explanation..

In your own words explain why a river changes as you move down stream …

Upper Course1. Small channel and lots of boulders in the river

(proportionally larger wetted perimeter!)

2. Lots of friction

3. Slower speed or velocity

4. Little spare energy

5. Less erosion and load

6. Channel remains narrow and shallow and discharge small

Copy

Lower Course1. Volume of water increases because of

tributaries (less water in contact with the wetted perimeter proportionally)

2. Less friction3. Higher velocity (faster)4. More spare energy and power 5. More erosion and load6. Channel becomes wider and deeper and

discharge increases

Copy

1. What is A

2. What is B

3. Which would have the higher velocity D or C

4. Which place would have the highest discharge

5. Would A or B have the largest load? Why?

A

EDB

C