meander🌊 Flashcards
what is a pool
a pool is an area of deeper water and greater eroision; due to an energy build up from less friction
what is a riffle
a riffle is an area of shallow water, with less erosion; created by deposition of coarse sediment
What does Helicoidal Flow do?
moves material from the outside of one meander benf and deposits it on the inside of the next meander bend
Helicoidal flow is..
a corkscrew like flow of water
Why do pools and riffles naturally develop in every straight river channel?
they develop as water twists and turns around obstructions in the water such as large boulders
Ultimately, what do pools and riffles cause?
faster and slower areas of water movement
the water to flow from side to side in a winding course
Which bend does the river cliff form on?
The outside bend
Which bend does the gently sloping river beach form on?
The inside bend
Why does the river cliff form?
Water moves more quickly on the outside bend, and so has more energy to erode
Why does the gently sloping river beach form?
Water moves more slowly on the inside bend, and so the river can deposit some of its load here- forming the beach.
Continuous erosion on the outer bend, and continuous deposition on the inner bend causes..
A meander to form in the river, which will migrate downstream and change shape over time
type of erosion in a meander
lateral erosion
How does the river erode the outside bend?
- hydraulic action- which is the sheer pressure of rushing water being forced against the river banks, dragging material away
- corrasion- which is the wearing away of the rivers bed and banks by its own load
- corrosion - which is the chemical erosion of rock by the flowing water, the acids in the water weaken the beds and banks
EXPLAIN THE FORMATION OF A MEANDER FULLY
In a straight river channel, pools and riffles will naturally develop as water twists and turns around obstructions in the river, such as large boulders.
This creates areas of faster and slower water movement:
• pools are areas of deeper water with greater erosion, due to an energy build up from less friction
•riffles are areas of shallow water with less erosion, created by deposition of coarse sediment.
Once pools and riffles have formed, the river flows from side to side in a winding course.
A corkscrew like flow of water called Helicoidal Flow moves material from the outside bend of one meander and deposits it on the inside bend of the next meander.
Water moving more quickly has more energy to erode, this happens on the outside bend and forms a river cliff.
The river erodes the outside bend through:
•hydraulic actuon- the sheer pressure of rushing water being forced against the river banks, dragging away material
•corrasion- the wearing away of the river bed and banks by the river’s own load
•corrosion- the chemical erosion of the river bed and banks by acids in the water which weaken them.
Water moves more slowly on the inside bend and here the river can deposit some of its load, this forms a gently sloping river beach.
Continuous erosion on the outside bend and continuous deposition on the inside bend causes a meander to form, which will migrate downstream and change shape over time.
