Test on rivers Flashcards
what is the watershed
The boundary of a drainage basin
What is a tributary
A stream or small river that joins a larger or another
What is the source
The starting point of a stream or river
What is a confluence
A point where two streams or rivers meet
What is the mouth
The point where a river leaves its drainage basin and flows into the sea
What is freeze thaw weathering
Where rainwater enters cracks in the rocks, freezes and expands when it turns to ice, cracking rock apart.
What is chemical weathering
When the air is polluted by factories and vehicles, causing it to become more acidic and then when the rain falls on certain rocks, the acid reacts with minerals and the rock decays.
What is biological weathering
Where the roots of plants can grow into the cracks in rocks and split the rock apart.
What is Hydraulic action
Where the motion of water against a rocks surface causes air to become trapped, compressing the rock and causing it to break off
What is abrasion
Where material carried by the river rubs against the bank and bed of the channel, wearing them away.
What is soloution
Where rivers water is slightly acidic, causing rocks to be dissolved.
What is attrition
Where rocks and sediment knock against each other, causing them to become rounder and smoother
What are interlocking spurs
Where a river curves around valley side sloped called spurs, creating interlocking spurs
How are waterfalls formed
When soft rock under hard rock is eroded by flowing water, causing undercutting and a steep sided gorge is formed.
What are meanders
Curves in a rivers course commonly found on flood plains
How are oxbow lakes formed
When a meander bends, its neck becomes narrower and the river erodes through the neck, cutting off the meander. Deposition at the neck seals off the bend.
What is a flood plain
Flat area of a land where a river will go into if it floods.
What is a levee
A natural embankment formed by flooding and deposition of sediment on the bank.
What are deltas
Built up layers of sediment in a fan shape.
What is a storm hydrograph
A graph that shows the change in river discharge after a storm
What is lag time
The time taken between peak rainfall and peak river discharge
What is the rising limb
The increase in river discharge on a storm hydrograph
What is the recession limb
The return of river discharge to base flow on a storm hydrograph
What is peak rainfall
The maximum amount of rainfall in (mm)
What is hard engineering
Human made structures designed to control rivers by force
What is soft engineering
Involves working with the natural processes and land to manage flood risk.
What are 5 examples of hard engineering
Flood barrage, river walls, man-made embankments, channel straightening, dams
What are 3 examples of soft engineering
Afforestation, flood-plain retention, river restoration
