Component 2 - Rivers Flashcards
Describe the water cycle
- Water evaporates and condenses into clouds,
- This falls onto the land, where some of it re enters the atmosphere through evapotranspiration, some will go into rivers. The rest soaks through the soil through infiltration and will return to the sea.
- Some undergoes percolation and turns into groundwater, this will take 1000s of years to return to the sea.
What are the 3 courses of a river?
Upper, middle and lower.
Where is the upper course of a river found?
The upper course is found high up in mountains.
What are the features of the upper course?
- The river doesn’t flow fast and is small.
- River rolls stones across the river bed through traction
- The river gathers minerals from mountain rocks
- River flows in interlocking spurs
- Forms V-shaped valleys
- Waterfalls
What are the features of the middle course?
- Meanders
- River flows faster
- Carries soils and clays, as well as minerals from upper course.
- Cities found here
- Murky
Where is the middle course of a river found?
The middle course is found on wider, flatter and open plains.
Where is the lower course of a river found?
The lower course is found near the coast.
What are features of the lower course?
- Extremely wide and flat
- River is slow at high tide, fast at low tide
- Supports large shipping lanes
- Sediment and minerals deposited making soil very fertile
- Industry, farms and ports found here.
What are the 4 types of erosion found mostly in the upper course?
Abrasion, Attrition, Hydraulic action and solution
How do V shaped Valleys form?
1.The river cuts downward into the land, as stones are dragged along the river bed.
2.The sides of the valley are exposed and are eroded by weathering.
3.The weathered material falles via gravity, into the river where it is carried away. Creating a V shaped valley
How are waterfalls formed?
1.Begins on a downhill slope when a layer of soft rock sits beneath a layer of harder rock.
2.Overtime the soft rock erodes faster, creating a step in the river
3.The soft rock is eroded further, until a steep drop is created - a waterfall
How are gorges formed?
- The waterfall undercuts the hard rock, which creates an unsupported overhang
- The hard rock collapses and the waterfall recedes.
- The collapsed rocks swirl around at the foot of the waterfall, where they use abrasion to create a plunge pool.
- This creates a gorge, which gets bigger as the waterfall recedes.
How are Oxbow lakes formed?
- The river meanders so far it connects back up with itself.
- The river takes shortest path, and sediment is deposited blocking off the old meander
- Forming an oxbow lake.
What are the main types of flooding?
- Glacial outbursts
- Fluvial flooding
3.coastal flooding
4.Saturation flood
5.Sewer flood - Flash flood
7.Catastrophic floods
8.Liquefation floods.
How do glacial outbursts happen.
1.Volcano erupts, or there is increased activity beneath a glacier.
2. Melting of huge volumes of ice causes torrent of water.
How does Fluvial flooding happen?
- When a river bursts its banks due to the inflow being greater than the outflow.
- Caused by heavy rain
What is the most common type of flooding in the UK?
Fluvial flooding
What is fluvial flooding good for?
Creating fertile land
What is coastal flooding caused by?
1.Sea storms and rising sea levels cause low lying land to flood
2. Worsened by climate change
How do Saturation floods work?
- Days of moderate rainfall cause the soil to become saturated, so it floods