geography revision rivers Flashcards
draw the water cycle and its main components
see example image
Define interception, surface run-off, groundwater flow (etc etc!)
throughflow
The movement diagonally downslope of water through the soil, as opposed to the vertical movement known as percolation.
interception - precipitation that does not reach the soil, but is instead caught by the leaves and the branches of plants and the forest floor.
infiltration- Infiltration is the process of water moving through soil and rock layers in the ground.
surface run off- when water runs over the ground
watershed- the area separating drainage basins
groundwater flow- when water flows under rock
condensation - when water turns into gas
precipitation - when water falls as rain, hail, sleet or snow
transpiration- trees and plants breath out water vapour through tiny holes in their leaves
What is a drainage basin?
The area of land drained by the river and its tributaries
What is a confluence of a river?
the point where two rivers meet
Define abrasion (or any other type of erosion!)
abrasion - rocks and stones bang against the river bed
attrition - rocks bang against each other and become rounder and smaller
corrosion- rocks such as chalk or limestone are dissolved in water and carried away by the flow of the river
hydraulic action- the force of the water creates cracks in the beds and banks of the river and bits break off
What is deposition? and what causes it?
When the sea loses energy, it drops the material it has been carrying. This is known as
deposition
Factors leading to deposition include:
.waves starting to slow down .and lose energy
.shallow water
.sheltered areas, e.g bays
.little or no wind
How do rivers transport sediment?
The river picks up sediment and carries it downstream in different ways.
There are four types of
transportation
:
Traction - large, heavy pebbles are rolled along the river bed. This is most common near the source of a river, as here the
load is larger.
Saltation - pebbles are bounced along the river bed, most commonly near the
source
.
Suspension - lighter sediment is suspended (carried) within the water, most commonly near the
mouth of the river.
Solution - the transport of dissolved chemicals. This varies along the river depending on the presence of soluble rocks.
Explain the formation of waterfalls, meanders and oxbow lakes, deltas (in step by step diagrams)
look at image
Explain how and why rivers need managing
rivers need managing to try and ensure that flooding does not happen again in an area. rivers can be managed by hard engineering strategies such as channel realignment or soft engineering strategies such as introducing floodplains where the excess water will flow to.
Evaluate soft engineering strategies
Soft engineering does not involve building artificial structures but takes a more sustainable and natural approach to managing the coast. Compared to hard engineering, soft engineering approaches are less expensive and are more long-term, attractive and sustainable as they work with natural processes.
.cheap
.not very effective
.looks good
.tries to work alongside nature
Evaluate hard engineering strategies
hard engineering tend to be more expensive and more unattractive than soft engineering strategies. hard engineering strategies try to work against nature whereas soft engineering strategies try to work alongside nature. hard engineering strategies are very reliable.
.expensive
.effective
.man made materials
.large scale
. bit of an eyesore
.provides immediate results
Case Study: What were the short term and long term impacts of the Somerset Floods of 2014
Long term
. no deaths but many lives impacted
Impact on house prices
.jobs
.building works
.£22.4 million spent
.insurance has gone up
short term
contaminated floodwaters full of sewage and pollution
. temporary accommodation
. medical (hard to get to)
. some villages cut off as roads flooded
.600 homes and 16 farms evacuated
What human and natural factors cause flooding?
HUMAN
Agriculture
urban land use
pollution
deforestation
NATURAL
Rainfall
Impermeable rock
Surface run-off
hydrological cycle
the water or hydrological cycle is the process by which water is continuously transferred between the surface of the earth and the atmosphere.
V shaped valley
The river transports rocks downstream and the channel becomes wider and deeper, creating a v-shaped valley between interlocking spurs
Plunge pool
pool of water found at the bottom of a waterfall it is an erosional feature that has been created by a combination of hydraulic action and the abrasion of the plunging water.
channel
this is where the river flows
interlocking spur
hill that a river meanders around in a v-shaped valley. When viewed from downstream, these spurs appear to be locked together.
tributary
a smaller river that branches of a bigger river
clouds blown inland
as the clouds are blown inland the water droplets get larger and larger
rivers
a large natural stream of water flowing in a channel to another store of water that is not a human body, a moving body of water that drains the ground
stores of water
lakes, oceans, rivers and the human body
source
where a river begins
mouth
where a river meets the sea
EROSION do the drawing
look at reference
how a river changes from source to mouth
UPPER COURSE
. begins
. high carrying capacity.
. high above sea level
. lots of rain
. flows very fast
. waterfalls
. v shaped valley
MIDDLE COURSE
.meanders
.cliff
.oxbow lake
.flooding
.river starts to widen
LOWER COURSE
. end
. estuary
. salt and freshwater mix
. could be tidal
. mudflats
TRANSPORTATION do the drawing
look at reference
DEPOSITION do the drawing
look at reference
Formation of a waterfall
- the river all flows over a steep drop creating a waterfall
2.erosion creates the plunge pool, soft rock erodes quickly - overhang collapses for the first time. Pebbles ,stones and boulders fall into the plunge pool.
- overhang collapses intermittently as the plunge pool is further eroded over about 1000 years and the waterfall retreats upstream
look at pictures for how to draw
facts about waterfalls
waterfalls form when there are horizontal strips of hard and soft rock
backsplash from the waterfall causes abrasion undercutting occurs behind the waterfall
meanders and oxbow lakes formation
MEANDER
Water moves slowly on the inside of the bend and the river deposits some load, forming a river beach/slip-off slope. Continuous erosion on the outer bank. and deposition on the inner bank. forms a meander in the river.
look in the book for image
OXBOW LAKES
Continual erosion and deposition narrows the neck of the meander. Often during a flood the river will cut through the neck. The river continues on its straighter path and the meander is abandoned. New deposition seals off the ends and the cut-off becomes an oxbow lake that will eventually dry up.
RIVER DELTAS FORMATION
DELTAS
.a delta is a landform found in the lower course of a river
.deltas form at the mouth of a river
.they are created by the process of deposition
.as a river empties into the sea, ocean or lake the velocity falls
.the river drops the material it has been carrying
. as this builds up, new land is formed, this is the delta
Case Study: Why did York flood in 2015?
the river foss and the river ouse both flooded in december, 2015 in the city of york. These were easily the most devastating floods York had experienced in at least 30 years. The community that were flooded were extremely upset as the flood defenses which should have protected them failed and the Christmas of 2015 was ruined. The people felt like a sacrifice as the council put a barrier to protect one part of York, but not the part that they were in. The barrier was let up, but the discharge was so large that both rivers flooded as the Foss retreated into the Ouse.
What hard engineering strategies were used after the York 2015 floods to improve protection?
. flood walls
. some houses have flood gates
. embankments
. flood pumps
. flood barrier - machinery controls this to make sure the water levels are equal
. culverts
.sluice gates
. 17 million pounds to improve and upgrade the barrier
. the defence starts in clifton ings
