Changes in Rivers and Landforms

Question 1

How does the long profile of a river change downstream?

Answer 1

1) Gradient - becomes gentler.
2) Velocity - Increases.
3) Depth - The depth increases.

Question 2

How does the cross profile change of a river when going downstream?

Answer 2

1) Valley - becomes wider, flatter

2) River - becomes wider and deeper (less turbulent) and larger sediment load (levees form)

Question 3

How do meanders form?

Answer 3

1) A meander river when moving water in a stream erodes the outer banks (river cliff) and widens its valley.
2) the inner part of the river has less energy and deposits silt (slip off slope).

Question 4

How do Ox-Bow lakes form?

Answer 4

1) Neck of the meander is gradually eroded
2) Water now takes the shortest route (deposition occurs on old meander)
3) Meander then becomes cut off, forming ox-bow lake

Question 5

How do Interlocking Spurs form?

Answer 5

When the river is in the upper course it has too little energy to erode through hard rock, so it goes around causing series of interlocking spurs.

Question 6

How are waterfalls and gorges formed?

Answer 6

1) As water falls the softer rock is eroded quicker than the harder rock undercutting the harder rock.
2) The hard, overhanging rock eventually collapses.
3) The collapsed rocks fall into the plunge pool causing erosion of the soft rocks and a deeper plunge pool.
4) This goes on continuously causing the waterfall to retreat upstream, leaving behind a gorge.