Other pages in this set

Page 2

Preview of page 2

Here's a taster:

RIVERS
RIVER PROCESSES
SEDIMENT SYSTEMS
Sediment in a river comes from a variety of sources. It may be from outside the river (exogenetic) that includes, mass movement, rill and
gully erosion and sheet wash. Or from within the rivers channel itself (endogenetic) that could be material from the stream bed and banks,
which is influenced by the power of erosion and the resistance of material to erosion.
CRITICAL EROSION VELOCITY (THE HJULSTROM CURVE)
Rivers either transport, erode, or deposit sediment (load).…read more

Page 3

Preview of page 3

Here's a taster:

You should note the following:
Sand is easily transported at lower velocities.
More velocity is needed to pick up material than to carry it in suspension.
In times of highest discharge, velocity increases, as does erosion.
The division between Transportation and deposition is small. This means that only a small decrease in velocity leads to sedimentation.
Competence is the maximum size of material a river can transport.…read more

Page 4

Preview of page 4

Here's a taster:

Hydraulic action
The force of water that hits river banks, and then pushes water into cracks. Air becomes compressed, pressure increased and the
riverbank may, in time collapse.
4. Solution/corrosion
A continual process, which is as a result of the chemical composition of the water.
TRANSPORTATION
Once friction has been overcome, transportation of material in a river begins. There are three main processes of transportation:
1.Suspension
Very small particles of clay and silt are carried in suspension.…read more

Page 5

Preview of page 5

Here's a taster:

B A river entering the sea or a lake, reducing velocity
C Water becoming shallower
D Increase in load
E River overflows its banks, depositing material on the flood plain
RIVER CHANNEL LANDFORMS
V-SHAPED VALLEYS AND INTERLOCKING SPURS
In the upper part of a river, vertical erosion is common creating a steep sided river valley. Interlocking spurs form as the river has to take
a winding course due to the highland areas that jut out.…read more

Page 6

Preview of page 6

Here's a taster:

OTHER LANDFORMS
Rapids
If the gradient of the river increases quickly or flows over gently dipping areas of harder rock rapids will result.
Flood Plains
At its most basic level this is land more likely to experience flooding.
If a river floods, silt is deposited on the land increasing its fertility, and
the height of the flood plain increases. The flood plain can be made
wider by the lateral erosion of meanders.…read more

Page 7

Preview of page 7

Here's a taster:

Pools, riffles, and meanders
These features occur due to both erosion and deposition. Pools are areas of deeper water and riffles are areas of shallower water. A pool
has more erosion than a riffle, and is caused by turbulence.
Meanders
The reasons for the development of meanders remain unclear, but they
appear to develop first in times of flood and are related to the occurrence
of sandbars. A river is meandering when its sinuosity is above 1.5.
Sinuosity = actual channel length / straight-line distance.…read more

Page 8

Preview of page 8

Here's a taster:

RIVER TERRACES
As shown in the diagram above river terraces offer superb sites for the location of settlement. They are the remains of former flood plains
that lie far above the extent of present day flooding as a result of vertical erosion caused by rejuvenation.
INCISED MEANDERS
If land is uplifted for a considerable period of time a river may cut downwards and form incised meanders.…read more

Page 9

Preview of page 9

Here's a taster:

Urbanisation.
COASTAL PROCESSES
INTRODUCTION
Of all the earth's natural environments, the coast is the most rapidly changing and dynamic. It can be defined in several ways, but at its
simplest, it is the place where land and sea meet and interact. The coast is under numerous pressures due to its pull for economic activity,
settlement, recreation and wildlife. Its form is greatly influenced by:
1. Terrestrial: Weathering, erosion, deposition, rock type/structure.
2. Human: Pollution, recreation, settlement, defences.
3. Atmospheric: Climate.
4.…read more

Page 10

Preview of page 10

Here's a taster:

There is limited direct sediment movement here as tidal currents are more important than wave action. Sewage outfalls, oil extraction and
fishing may occur.
BERMS AND RIDGES
On the beach itself, different features arise as a result of the action
and strength of waves on sand and shingle.
Berms are formed as sand/shingle is slowly moved up a beach by
successive incoming tides - they are more common on shingle
beaches, whilst ridges and runnels are found more on sandy
beaches. Both form 'crests'.…read more

Comments

No comments have yet been made

Similar Geography resources:

See all Geography resources »See all resources »