Hydrograph And Fluvial Process And Features Flashcards
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Peak flow
Maximum discharge to a river
Rising limb
The rising flood water in the river
Base flow
Average amount represents
The date to day discharge of river due ground floor water seeps info channel
Lag time
Time difference between the peak of rainstorm to the peak flow of the river
Overland flow
The same as surface run off water water runs over the surface as it cannot infiltrate land
Through flow
Takes place when the soil is completely saturated with water rate of water movement is slow e.g. surface run off
What causes a flashy hydrograph
Small basin
High density of water speed up water transfer
Impermeable land Leads to rapid overland flow
Urbanisation encourages rapid water transfer
Steep slopes rapid overland flow
Saturate soils causes rapid overland flow
Heavy rains exceed infiltration capacity of vegetation
What causes a flat hydrograph
Large basin and a low density of water slows down water transfer
Permeable rocks creates a slow transfer of groundwater flow
Forests causes interception
Gentle slopes slow down water transfer
Soils soke up water and slows down water transfer
Light rain falk will slow down the water transfer
Floodplains definition
An area of low lying ground adjacent to river formed by sediment from river and is proned to floods
Levees
A ride of sediments deposited naturally along banks by overflowing water
Estuaries
The tidal mouth of a large river where the tide meets the stream
Floodplains formation
When rivers flood on flood plains it slows down and deposits eroded materials that it was transporting
This builds up the floodplains
Meander and floodplains
Meanders migrate across floodplains makes it more wider
Deposition also happens on slip off slopes of meander also builds up floodplains
Levees are natural embankments
During a flood eroded materials are deposit along edge of the river channel
Heavy material are deposit close to river channel as it is the first to drop when the river slows down
This continues to create a levee
Examples of levee
New orleans
Yellow river China
Estuaries are tidal areas where the river meets the sea 🌊
Water here is tidal so the river levels changes all the time
The water floods bank of river which has sand and silt onto Valley floor
As the tide is at its highest point water slows down and deposits
This builds up as it continues
What happens at lowest tides to the estuaries
The muddy banks are exposed
What it created in estuaries
Mudflats e.g the Severn estuaries
Meanders formation step one
The current is faster on the outside than inside of the bend as the river chanel is deeper
There s less friction to slow water down
Meanders formation step two ✌
So more erosion happens to the outside bend forming river cliffs
Meanders formation step three
The current is slower on the inside of the bend because the river channel is shallower as there is more friction to slow the water down
Meanders formation step four
So erode materials is deposited on the inside of the bend forming a slipped off slopes
Oxbow lake step one
Erosion causes the inside of the bend to get closer until there is a small bit of land left between bend the neck
Oxbow lake step two ✌
The river breaks through the land usually during a flood and the river slows along the shorter course
