Hydosphere Flashcards
Fluviale Erosion
The break up of rocks by the action of the river
Transportation
The movement of eroded material
Deposition
The laying down of material which has been transported by the river
Sediment supply zone
The area of a river which is the source for alluvium that is transported down the river
Physical weathering
The process of physical elements breaking down rocks
Chemical weathering
The breakdown of rocks due to chemicals
Hydraulic action
The force of water impacting the rock and forcefully flooding small cracks, breaking down the rocks
Corrosion
The process by which chemicals in the water such as carbonic acid dissolve the rock and wash them away
Attrition
Particles in a river hit eachother reducing their size
Where do rivers form
High in the mountains where gradients are steep, so they flow quickly and erode vertically
Abrasion
The process of small rocks and pebbles in the water grinding against rock and wearing it away
Freeze-thaw
Weathering sides of valley, breaking rocks and steepening sides
U shaped valleys are formed by
Rivers cutting into rocks
Waterfall
An erosional feature found in the upper course of a river
Strata
Bed of horizontal rock with varying thickness
Differential erosion
Softer rock underneath eroded so rock on top collapses
What causes differential erosion
Hydraulic action, abrasion, corrosion
Plunge pool
Pool formed at bottom of waterfall due to force of water and rocks carried by it
What will happen to overhang after a period of time
It will collapse due to lack of support and process will start again
Gorge
After a process of repeated erosion, the waterfall retreats into the hillside forming a Gorge
Where are meanders found
Middle and lower course of a river
What causes a meander
Difference in speed between the inner and outer bank
When do meanders form
When a river has to bypass a an obstruction such as a large boulder or rocky outcrop
What is the first stage in the formation of a meander
Formation of Riffles and pools
What is a Riffles
A shallow area formed along the inner bank of a river
How is a riffle formed
The water is slower on the inside or the bend so sediment is deposited and builds up reducing the depth of the water
What is a pool
Deeper part of river caused by faster moving water
Helicoidal flow
Spiralling current with surface water flowing outwards and sub-surface water flowing inwards
What does the helicodial flow do
Creates more erosion and deposition until a river cliff is formed on the outer bank and a slip of slope on the inner
Over the time, what happens to the meander
It becomes more and more sinuous and the neck becomes narrower due it erosion until in a period of flooding the river will take the quickest path possible and break the curve
After the meander is cut, what happens
The water flowing and an oxbow lake is formed
Drainage basin
The area drained by a river and it’s tributaries
Watershed
Boundaries of the drainage basin
Where does the watershed usually occur
On high land as water can only flow downwards
Hydrological cycle
The process which distributes water in a drainage basin
Advection
The process of wine moving clouds from over water to land where precipitation occurs
Precipitation
Rain, the main input to the system
Runoff
The sum of all the water in the drainage basin that flows of the surface
Streamflow
Transfer through river Channels
Surface flow
Water that travels on the surface of the basin
Interception
The process of plants shielding the ground from precipitation
Stem flow
When water is intercepted by vegetation and guided to the ground
Infiltration
The process of water soaking into the soil
Soil moisture
The retention of water in the soil
Throughflow
The transfer of water underground
Groundwater
Water stored in the ground by rock
Primary output of a drainage basin
The sea
Evapotranspiration
The loss of water from plants to the atmosphere, and the secondary output of water from a drainage basin
Evapotranspiration
The loss of water from plants to the atmosphere, and the secondary output of water from a drainage basin
Hydrograph
Graph to show how the water in a drainage basin is effected by a storm
What does a hydrograph measure
Precipitation and discharge rate
What is shown by the bar chart
Precipitation
What is shown by the line graph
Discharge
What is the unit of precipitation
mm
Discharge is measured in
Cumecs
Peak rainfall
When rainfall is highest
Peak discharge
When discharge is highest
Lag time
Difference between peak rainfall and peak discharge
Base flow
Dotted line which shows the amount of water which would normally be in the Chanel without a storm
Approach segment
Flat section of the graph before the rising limb
Rising limb
Shows amount of water increasing
Falling limb
Shows amount of water decreasing
What happens to Lag time in larger basins
It’s longer
What happens to falling and rising limb in larger basins
It’s shallower
What happens to lag time in smaller basins
Lag time is shorter
What happens to rising and falling limbs in smaller basins
They’re steeper
In a lower or elongated basin, what happens to the lag time
It is longer
What happens to rounded basins lag time
The lag time is shorter
What does permeable rock do
Absorb water Resultat on decreased surface flow and smaller peak discharge
What happens with impermeable rock
No infliltration takes place
How does porosity of the soil affect the lag time
Porous soils make a longer lag time and dense soils crate a shorter lag time
What does urbanisation do to the lag time
Make it shorter
What does vegetation do to the lag time
Elongate it
What does deforestation do to the lag time
Makes it shorter
