Rivers Flashcards
What are the three stages of a river
Upper course, middle course, and lower course
What are the main river processes
Erosion, transportation, and deposition
What are the 4 types of river erosion
Hydraulic action- the force of water breaking a rock
Abrasion- big boulders smash into side of the riverbed
Attrition- rocks smashing together and becoming smaller and rounder
Solution- river water dissolving minerals in rocks
What are the 4 types of transportation in a river
Traction- large rocks rolled along the riverbed
Saltation- small pebbles bounced along
Suspension- Fine material carried in the water
Solution- dissolved material carried by the river
What landforms are found in the upper course of a river
V-shaped valleys, interlocking spurs, waterfalls, gorges, and plunge pools
How do waterfalls and gorges form
- A waterfall forms when hard rock lies above soft rock
- The soft rock erodes, creating an overhand
- The overhang collapses, and the process repeats, forming a gorge over time
What landforms are found in the middle course
Meanders and oxbow lakes
How do meanders form
- Water flows faster on the outside bend, eroding the bank
- Water flows slower on the inside bend, depositing small sediment
- This creates a curved meander over time
How do oxbow lakes form
- Erosion narrows the neck of a meander
- During a flood, the river cuts through the neck
- Deposition seals off the old meander, leaving an oxbow lake
What landforms are found in the lower course
Floodplains, levees, and estuaries
What is a floodplain
A wide, flat area of land next to a river that forms when river overflows
What are levees
A raised bank or wall that prevents flooding
How are levees formed
- During floods, the river deposits sediment on its banks
- Over time, these deposits build up into raised levees
What is an estuary
The wide mouth of a river where it meets the sea, with tidal mudflats forming due to deposition
What is a rivers long profile
A side view of a river from its source to its mouth, showing how its gradient changes
What is a rivers cross profile
A slice across a river valley, showing how the shape changed from the upper course to the lower course
Why does a rivers velocity increase downstream
The channel becomes wider, deeper, and smoother, reducing friction
What is river discharge
The volume of water flowing in a river, measured in cubic metres per second
What is hard engineering for river management
Dams and reservoirs- store water and control flow
Channel straightening- speeds up water flow
Embankments- raised banks to prevent flooding
What is soft engineering for river management
Floodplain zoning- restricting building in flood prone areas
Afforestation- planting trees to absorb water
River restoration- Returning rivers to their natural state
