River Invesitgations Flashcards
Discribe the process of deposition
When the river runs out of energy during a part of the flow heavy rocks are dropped at the bottom of the river. This can happen when a river meets its mouth or during a shallow area
Describe the process of erosion
Erosion occurs during the whole journey of the river. It is where abrasion (rocks carried by the river rub and scrape the bank away), solution (soluble rock are dissolved into the river), attrition (rocks hit against each other breaking into smaller pieces and becoming more round) and hydraulic action (the river forces air against the banks and the pressure weakens the rocks) break off bit of the area surrounding the river deepening and widening it
Describe the process of transportation
The 4 different ways a river transports rock from a to b through:
Solution: dissolved minerals are carried along the river
Suspension: small materials are carried along
Traction: large boulders and rocks roll along the river bed
Saltation: small pebbles and stones are bounced along the river bed
List 4 different river land forms
Water falls, meanders, Ox bow lakes, flood plains
How does a meander form?
. Because one (outer) side of a river erodes quicker, flows more on the outer bend than the inner bend occurs as the outer part of the river is deeper than the inner part. rivers flow in a helical flow because the outside bend is quicker than the inside bend because the inside bed is slow and deposits on one side forming a slip off slope and on the outer bend forms a river cliff
How does a water fall form? And how do plunge pools and over hangs form?
A water fall forms when a river meets 2 different types of rock. The tops layer from which the water falls is more resistant than the bottom layer. This landform occurs in the upper course. Water falls erode backwards as the less resistant rock is under mined by water so the top rock becomes a over hang. The over hang the collapse under its own weight and the process starts again (over years steep side occurs where it has erode back, this is called a gorge). The plunge pool forms as abrasion and hydraulic action erode where the water hits the bank and makes a grove where rocks get stuck and are effected by attrition.
How does an oxbow lake form?
Through hydraulic action the fast flowing parts of a meander cut though the spur between then as they erode close together it is called a neck. During a flood the neck is cut and the meander is replaced by a straight line. Because their is no erosion deposition means the meander is blocked by land and becomes a ox bow lake which will dry and be a meander scar
How is a flood plain formed?
Because one side of a meander has a high erosional power and the other has low erosional power and high deposition power the meanders move left and right eroding and lowering ground around it the area of low ground will be know as the flow plain. When the river flood this land will have water on it and over time the small sediment deposited by the river when it floods build up and levees become higher forming a natural flood defence
What is long profile?
Shows change is the river in the height or a rivers course from its source to mouth
State what would happen to (according to bradshaws model) Discharge Occupied channel width Channel depth Average velocity and load quantity As they go down stream...
They will increase
State what would happen to (according to bradshaws model) Sediment size Channel bed roughness And gradient As they go down stream...
They decrease
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What does peam stand for?
Point - evidence - anomoleas - manipulation (for example sight 1 has 5x larger sediment than sight 5)
What is the mouth?
Where the river meets the sea
What is the source?
Where the river starts
What is the drainage basin?
An area of land that absorbs any water that falls on it into the river or via a tributary
