River Landscapes Flashcards
(48 cards)
What is a drainage basin?
The area of land drained by a river
What parts of a river are included in a drainage basin?
Watershed, source, mouth, tributaries and confluences
How does precipitation travel to a river?
Travels across the surface of the drainage basin and underground through soil or rocks
What does a long profile show?
The height and distance downstream from a river’s source to its mouth
What does a cross profile show?
The depth and width of the channel at any point along the long profile.
What are the 3 sections of a river?
Upper, middle, lower
What is abrasion in rivers?
Sediment carried by river rubbing along the river channel
What is attrition in rivers?
Sediment carried by the river colliding with one another to become smaller and more rounded
What is hydraulic action in rivers?
The sheer force of the water eroding the channel and valley
What is lag time?
The difference between peak rainfall and peak discharge
What is the rising limb?
The rapid rise in water after a period of heavy rainfall
What is saltation in rivers?
Sediment being transported by bouncing along the riverbed
What is solution in rivers?
The process of rock minerals being dissolved in water
What is suspension in rivers?
The process of sediment being transported by the river water
What is traction in rivers?
The process of sediment being rolled along the riverbed
What is weathering in rivers?
The sub-aerial breakdown and decay of rocks in the river valley - chemical, biological, mechanical
What type of material is first deposited when a river loses energy?
The heaviest
How are interlocking spurs formed?
- A river erodes softer, less-resistant rock in the valley
- Harder, resistant rock is left
Where in the course of a river are interlocking spurs found?
Upper course
How are waterfalls and gorges formed?
- A layer of hard, more resistant rock lays over a band of soft, less resistant rock
- Hydraulic action and abrasion erode the less resistant rock
- This creates a waterfall, plunge pool and eventually a gorge as it retreats
Where in the river course are waterfalls and gorges found?
The upper course
What are meanders?
Bends in the river
How are meanders formed?
Erosion and deposition:
1. HA + abrasion laterally erode the outer bend of a river channel
2. Sediment is deposited on the inner bend of the river
How are oxbow lakes formed?
- A river erodes the meander neck and flows through a new, straight channel
- Deposition occurs at the neck and seals off the meander bend
- Creating an oxbow lake