Key Stuff Flashcards
(63 cards)
1
Q
Precipitation
A
water falling from sky as rain, hail, sleet or snow
2
Q
throughflow
A
horizontal movement of water through the soil
3
Q
baseflow
A
- flow of water below the water table (groundwater flow)
- towards river channel
- slowest flow of water
- result of water percolating through soil/bedrock
4
Q
overland flow
A
movement of water across surface
5
Q
infiltration
A
movement of water down into the soil
6
Q
throughfall
A
movement of precip from vegetation to surface
7
Q
interception
A
capture of precip by vegetation so it doesn’t fall directly onto ground
8
Q
stem flow
A
movement of captured precipitation down the stems and trunks of vegetation
9
Q
surface storage
A
water stored that has not infiltrated the surface
10
Q
groundwater storage
A
percolated water that is held in aquifers below the water table
11
Q
antecedent moisture
A
moisture retained in soil after a period of rainfall
12
Q
evapotranspiration
A
combination of moisture loss due to evaporation and transpiration
13
Q
lag time
A
period between peak rainfall and peak discharge
14
Q
peak discharge
A
time when the river has maximum amount of water flow
15
Q
rising limb
A
the line on the graph that represents discharge increasing to peak discharge
16
Q
falling limb
A
the line on the graph that represents the discharge decreasing from the peak discharge
17
Q
traction
A
transportation of large sediment by rolling along river bed
18
Q
pool
A
deep channels where the river flows
19
Q
riffle
A
shallow areas in river channel
20
Q
laminar flow
A
low velocity movement of water in a uniform pattern, parallel streams. no cross-currents or swirls. one direction.
21
Q
turbulent flow
A
- disorderly flow
- many changes in velocity (speed & direction)
- caused by friction, esp when river channels are irregular
- eddies (swirling reverse currents) common in this flow, downstream direction
22
Q
suspension
A
transportation where particles are suspended in flow
23
Q
saltation
A
sediment hops along river bed
24
Q
abrasion
A
grinding of sediment on river bed/bank
25
hydraulic action
water forces air into cracks applying pressure and weakening rock
26
solution
transportation of dissolved material
27
porosity
determines how much water can be absorbed and stored by the rock
28
permeability
rate that water can pass through a rock
29
water table
line separating the unsaturated zone and saturated zone
30
recharge
refilling zone of saturation due to lack of water
31
thalweg
line of maximum velocity, also deepest point
32
helicoidal flow
- corkscrew movement of water (spiral-shaped)
- occurs in bends in river channel (meanders)
- responsible for erosion/deposition in meander
- potentially forms river cliff
33
bluff
edge of floodplain
34
soil water
water present in soil after infiltration
35
drainage basin
an area of land drained by a river and its tributaries
36
watershed
the line dividing drainage basins from each other (highest land surrounding the basin)
37
transpiration
the evaporation of water from a plants leaves stem or flowers
38
river discharge
the volume of water flowing through a river channel; measured at any given point in cubic metres per second
39
channel flow
water that moves through established channels, like rivers or streams
40
aquifer
- underground water stores
- a body of porous rock or sediment saturated with groundwater
41
spring
a natural outlet of groundwater, i.e. anywhere where groundwater flows out onto the surface
42
formation of spring
1) where permeable rock meets impermeable rock, causing infiltrated water to build up and eventually escape as a spring
OR
2) where the water table meets the surface (especially on a hill) causing the discharge of water
43
baseflow hydrograph
the lvl of water a river holds **without** contributions by overland flow
- normal discharge line (without precip)
44
stormflow hydrograph
the additional water in river bank during storm, made of overland flow + throughflow
45
bankfull discharge
- max capacity of river
- if discharge > this, river will burst banks and flood
46
drainage density
total length of all rivers and streams in a drainage basin divided by the total area of a drainage basin
- indicator of how well the drainage basin is drained
47
drainage density hydrograph impact
high drainage density = more streams and rivers, so peak discharge is high and short leg time. due to lots of rivers, water is drained quickly, so steep falling limb
low drainage density = overland flow more likely to infiltrate than make way to channels, so long lag time, low peak discharge
48
cavitation
air bubbles go into gaps and implode due to pressure, weakening the rock
49
sedimentation
the process of being deposited as a sediment
50
hjulstrom curve
logarithmic graph
- shows how velocity of river affects the material and whether it will be eroded, transported or deposited
51
straight river channel
- mainly upper course
- single, straight channel
- vertical erosion prevalent
- thalweg moves from side to side
52
meandering river channel
- middle and lower course of the river
- series of bends and curves from side to side
- deposition on inside of bend
- erosion on outside of bend
53
braided river channel
- large sediment deposits within channel, causing many channels to form, separated by islands of sediment
- usually occur where discharge fluctuates
- river deposits when it loses energy
- doesn't usually occur in upper course
54
river cliff
a cliff created when the bank is undercut by erosion on the outside of the bend
55
point bar
a deposit of fine sediment, e.g. sand on the river bank inside of a meander bend.
usually changes position as meander changes shape
56
water abstraction (human impact)
- removal of water from a water body like a river, lake, reservoir or groundwater store
- unsustainable if abstraction rate is higher than replenishing rate
effects:
- water can deplete on surface and groundwater level
- affects channel flow and discharge, more deposition
- water table may fall when groundwater overexploited, so less groundwater seepage into the above groundwater stores.
causes above-ground water levels to fall?
57
water storage (human impact)
- damms directly stop and control channel flow, barrier in way of river channel
- reservoirs behind dams can raise water table behind dam, affecting soil saturation
- may lead to lowering of water table in other areas water that wld be in other areas is being stored in dam
- usually v. large (reservoirs), so store a lot. LOT of water can enter atmosphere through evap etc, increasing cloud formations so affecting precip.
58
causes of flooding
- prolonged rainfall
- intense rainfall
- impermeable surfaces (land use...)
- melting snow (temperatures...)
59
impacts of flooding
- sediment onto floodplain, waterlogs plants and endangers wildlife
- floods transport materials, can deposit them in clean water supplies
- damage buildings, destroy hmes/businesses etc
- homelessness, poverty, disease
60
predicting flood risk
- probability of a flood of a certain size can be predicted based on past flooding records. known as **flood recurrence interval**
- can be modelled using software / other equipment, to predict how diff circumstances would affect flooding (slope, topography, precip rates etc)
- helps inform low/med/high risk, and so decided construction work / insurance policies (important)
61
adaptation
accepting flooding is happening and adapting to it once the flood event has happened
62
mitigation
attempting to reduce the impacts of the flood events before it happens
63
infiltration rates (clay and sand)
clay: 0-4 mm/hr
sand: 3-12 mm/hr
