Rivers Flashcards
define abrasion
rocks carried along river wear down river bed/banks and scrape against it wearing it down
side profile
cross section of river bed
define attrition
rocks being carried by the river smash/collide together and break into smaller smoother rounder particles
dams and resevoirs
barrier built to interrupt river flow and create a water storage lake to control the discharge of a river
discharge
the quantity of water that passes a given point on a stream or river bank within a given period of time
embankments
raised banks constructed along the river; they effectively make the river deeper so it can hold more water - protects land
lateral erosion
sideways erosion by a river on the outside of a meander channel. it eventually leads to the widening of the valley and contributes to the formation of a flood plain
estuary
the tidal mouth of a river where it meets the sea; wide banks of deposited mud are exposed at low tide
flood plain zone
attempts to organise the flood defences in such a way that land is near the river and often floodss - can be used for pastoral farming, playing fields etc
flood plain
a relatively flat area forming the valley floor on either side of a river channel, which is sometimes flooded
hydrograph
a graph which shows the discharge of a river related to rainfall over a period of time
levee
embankment of sediment along bank of river - may be formed naturally by regular flooding or be built up by people to protect an area against flooding
saltation
small rocks and particles carried by river flow bounce down the river bed
soft engineering
involves the use of natural environment surrounding a river using schemes that work with the rivers natural processes
traction
large particles e.g boulders and rocks are rolled along the river bed by the force of water at times of high discharge
solution
soluble particles are dissolved in the river such as calcium carbonate (requires little energy)
channel straightening
removing meanders from the river to make the river straighter - allows it to carry more water downstream so it doesn’t build up and is less likely to flood
suspension
fine solid material (clay/sand particles) held/carried in water while the water is moving even at low discharges
traction
the rolling of boulders and pebbles along the river bed
vertical erosion
downward erosion of river bed
water table
Current upper level of saturate rock soil where no more water can be absorbed
Ground water flow
Water flowing through the rock layer parallel to the surface
Through flow
Water flowing through the soil layer parallel to the surface
Surface run off
Water flowing on top of the ground
Evaporation
Water lost from ground/vegetation surface
Transpiration
Water lost through pores in vegetation
Ground water
Water stored in rock
Perculation
water seeping deeper through the rock
Soil moisture
Water held in the soil layer
Infiltration
Water sinking into the soil/rock from the ground surface
surface storage
Water held on the ground surface e.g. puddles
interception
Water being prevented from reaching the surface ground by vegetation or trees
how does human activity affect surface run-off
tarmacking roads increases flood risk as water is infiltrated
how does human activity affect interception
deforestation stops stem flow as less water is intercepted
what is the source
the start of a river
what is confluence
where a tributary joins the main river
describe the characteristics of upper course
narrow steep
describe the characteristics of middle course
wider shallow