River Landscapes in the UK

Question 1

Abrasion

Answer 1

Rocks carried along by the river wear down the river and banks. Most common form of erosion.F

Question 2

Attrition

Answer 2

Rocks being carried by the river smash together and break into smaller, smoother and rounder particles.

Question 3

Cross Profile

Answer 3

The side to side cross-section of a river channel and/or valley.

Question 4

Dam and Reservoir

Answer 4

A barrier (made of earth, concrete or stone) built across a valley to interrupt river flow and create a man-made lake (reservoir) which stores water and controls the discharge of the river.

Question 5

Discharge

Answer 5

The quantity of water that passes a given point on a stream or river-bank within a given period of time.

Measured in cubic metres per second.

Hydrographs show this over time.

Question 6

Embankments

Answer 6

Raised banks constructed along the river; they effectively make the river deeper so it can hold more water. They are expensive and do not look natural but they do protect the land around them.

Question 7

Estuary

Answer 7

The tidal mouth of a river where it meets the sea; wide banks of deposited mud are exposed at low tide.

The river here is tidal, rising and falling each day.

Deposits are made when it floods carrying sand and silt which is deposited at its highest tidal point.

Creates mudflats which are exposed at low tide. E.g. is the River Severn.

Question 8

Flood

Answer 8

Occurs when river discharge exceeds river channel capacity and water spills out of the channel onto the floodplain and other areas.

Question 9

Flood Plain

Answer 9

The relatively flat area forming the valley floor on either side of a river channel, which is sometimes flooded.

When a river floods onto a pain it slows down and deposits eroded material. This builds up the flood plain.

Question 10

Flood Plain Zoning

Answer 10

This attempts to organise the flood defences in such a way that land that is near the river and often floods is not built on. This could be used for pastoral farming, playing fields, etc. the areas that rarely get flooded would therefore be used for houses, transport and industry.

Question 11

Flood Relief Channels

Answer 11

Building new artificial channels which are used when a river is close to maximum discharge. They take the pressure off the main channels when floods are likely, therefore reducing flood risk.

Question 12

Flood Risk

Answer 12

The predicted frequency of floods in an area.

Question 13

Flood Warning

Answer 13

Proving reliable advance information about possible flooding. Flood warning systems give people time to remove possessions and evacuate areas.

Question 14

Fluvial Processes

Answer 14

Processes relating to erosion, transportation and deposition by a river.

Question 15

Gorge

Answer 15

A narrow, steep sided valley, often formed where a waterfall retreats upstream.

Question 16

Hard Engineering

Answer 16

Involves the building of entirely artificial structures using various materials such as rock, concrete and steel to reduce, disrupt or stop the impact of river processes.

Question 17

Hydraulic Action

Answer 17

The force of the river against the banks can cause air to be trapped in cracks and crevices. The pressure weakens the banks and gradually wears it away.

Question 18

Hydrograph

Answer 18

A graph which shows the discharge of a river, related to rainfall, over a period of time.

Question 19

Interlocking Spurs

Answer 19

A series of ridges projecting out on alternate sides of a valley and around which a river winds its course.

Question 20

Lateral Erosion

Answer 20

Sideways erosion by a river on the outside of a meander channel. It eventually leads to the widening of the valley and contributes to the formation of the flood plain. Dominant in middle and lower courses of a river.

Question 21

Levees

Answer 21

Embankment of sediment along the bank of a river. It may be formed naturally by regular flooding or be built up by people to protect the area against flooding.

The heaviest material is deposited closest to the river channel and overtime this builds up.

Question 22

Long Profile

Answer 22

The gradient of a river, from its source to its mouth.

Question 23

Meander

Answer 23

A pronounced bend in a river.

Question 24

Ox-bow Lake

Answer 24

An arc-shaped lake which has been cut off from a meandering river.

Question 25

Precipitation

Answer 25

Moisture falling from the atmosphere as rain, hail, sleet or snow.

Question 26

Saltation

Answer 26

Particles bouncing down the river bed.

Question 27

Soft Engineering

Answer 27

Involves the use of the natural environment surrounding a river, using schemes that work with the river’s natural processes. Soft engineering is usually much cheaper and offers a more sustainable option as it does not interfere directly with the river’s flow.

Question 28

Solution

Answer 28

Soluble particles are dissolved into the river.

Question 29

(Channel) Straightening

Answer 29

Removing meanders from the river to make the river straighter. Straightening the river (also called channelizing) allows it to carry more water quickly downstream, so it doesn’t build up and is less likely to flood.

Question 30

Suspension

Answer 30

Fine solid material held in the water while the water is moving.

Question 31

Traction

Answer 31

The rolling of boulders and pebbles along the river bed.

Question 32

Vertical Erosion

Answer 32

Downward erosion of a river bed. V shaped. More dominant in the upper course where the terrain is steeper.

Question 33

Waterfall

Answer 33

Sudden descent of a river or stream over a vertical or very steep slope in its bed. It often forms where the river meets a band of softer rock after flowing over an area of more resistant material. The erosion of the soft material forms a step. Eventually the hard rock is undercut by erosion and collapses creating a deep plunge pool

Question 34

Cross profile

Answer 34

Shows what the cross section of a river will look like.

Question 35

Four processes of transportation

Answer 35

Traction (pushed along), saltation (pebble sized bounced along), suspension (small particles carried along) and solution (dissolve).

Question 36

Why does a river slow down and deposit?

Answer 36

1) Volume of water falls.
2) Amount of material increases.
3) Shallower.
4) Reaches its mouth.

Question 37

How are meanders formed?

Answer 37

Develops in middle and lower course of a river where there are shallow and deep sections.

The current on the outside is faster as it’s deeper with less friction. Erosion forms river cliffs.

The current on the inside is slower as it’s shallower with more friction. Deposition forms slip off slopes.

Question 38

How are ox-bow lakes formed?

Answer 38

When meanders get larger, there is only a small bit of land between the bends (the neck) which eventually breaks through during a flood. The river flows along the shortest course and then deposition cuts off the meander.

Question 39

What is the lag time of a river?

Answer 39

The delay between peak rainfall and peak discharge.

Question 40

What are the rising and falling limbs on a hydrograph?

Answer 40

Rising limb is when the river discharge is increasing.

Falling limb is when the river discharge is decreasing.

Question 41

What impacts flooding?

Answer 41

1) Prolonged rainfall - saturated soil increases runoff into rivers.
2) Heavy rainfall - Too much rainfall for inflltration
3) Geology - clay soils and some rocks are impermeable which increase runoff.
4) In steep sided valleys, water reaches channel much quicker.

Changing land use impacts flood risk - concrete buildings, roads, removing trees