Karteikarten
Rivers, Floods and Management Key Terms
Karten in diesem Stapel (101)
- 1AbrasionWearing of the shoreline by sediment carried by water flow. Erosion by scraping, scouring and rubbing of load in contact with banks and bed (Corrasion)
- 2AfforestationPlanting trees in the catchment area of a drainage basin to increase interception storage and evapotranspiration
- 3AquiferPorous and Permeable rocks
that can store water - 4Antecedent RainfallRain that falls on already saturated soil. Soil cannot take any more water so it becomes surface runoff.
- 5AttritionReduction/rounding of particles of sediment carried in water by repeat collision with other sediment/banks
- 6BankfullThe state of flow of a river when it completely fills its channel (at capacity)
- 7BedloadLarger material, cobbles, pebbles and sand transported by saltation.
- 8Braided streamInterconnected channels separated by deposited material
- 9CapacityThe total volume of sediment
a river can carry - 10CalibreMeasurement of the long axis
of sediment in a river - 11Catchment AreaThe land that drains water into a
particular river system - 12Channel EnlargementDeepening/Widening of the channel to accommodate larger discharge
and transport it faster - 13Channel FlowMovement of water within the
river channel - 14CompetenceThe maximum size (calibre) of load a river is capable of transporting
- 15CondensationProcess that water vapour is
converted into water - 16CorrasionErosion by friction of load in contact with banks/bed (Abrasion)
- 17CorrosionDissolving of carbonate rocks (eg. Limestone) in water flow.
- 18Cross sectional areaChannel depth x Chanel width
- 19DamsBarriers that hols back water and create a large reservoir behind them.
- 20DefecitA Shortage eg. soil moisture
- 21DeltasFormed when the amount of sediment delivered to the mouth of a river exceeds the amount taken away by waves, and so it is deposited.
- 22DepositionWhen the rivers competence is
not great enough to carry the
sediment, so it is dropped. - 23DischargeVolume of water flowing in a river per second, measured in cumecs
(Cubic metres per second) - 24Dissolved load(Solution load) When weak acids in water flow dissolve material in solution.
- 25DistributarySmall channel that leaves the main river on a delta (one of the braided channels)
- 26Drainage BasinThe area in which water will flow into
one particular river - 27DredingThe removal of sediment from the river bed to increase channel depth
- 28EddiesFast-flowing circular currents of water in the rivers flow
- 29EvaporationTransformation of water into water vapour by heat from the sun
- 30Field capacityAmount of water that can be held by the soil before rainfall becomes antecedent.
- 31EvapotranspirationLoss of water from a drainage basin into the atmosphere from the processes of evaporation and transpiration.
- 32FlocculationRiver load particles joining together on contact with salt in sea water, increasing weight and causing them to be deposited
- 33FloodA temporary excess of water that spills over onto the land
- 34Flood AbatementReducing possibility of flooding by managing land use upstream. Eg. afforestation
- 35Flood embankmentsBuilding up of levees around river channel
- 36Flood interception schemesIntercepting the channel, diverting part of the flow for town/agricultural use and to move water to flood retention areas.
- 37Flood proofingTemporary protection against flooding. Eg. sandbags or Permanent Eg. Flood proof walls/flood gates
- 38Flood relief channelConstructed to redirect excess water
ahead of a settlement - 39Flood wallsIncreasing height of channel, preventing water spilling out over floodplain
- 40Flood plainFlat and broad valley floor created by successive flooding events depositing alluvium (sediments)
- 41FrequencyHow often flooding occurs
- 42GorgeNarrow, rocky, steep-sided valley, created by recession of a waterfall
- 43Graded profileAlso called the long profile
- 44Groundwater storageStorage of water in permeable
rock under subsoil - 45Groundwater flowMovement of water through
permeable rock under subsoil - 46Hard engineeringFlood management strategies that involve structural measures offering protection through engineering.
- 47Helicoidal flowWater flow pattern where the fastest current spirals across the channel
in a corkscrew motion - 48Hjulstroms CurveGraph showing relationship between velocity, erosion and deposition.
- 49Hydraulic actionForce exerted by moving water on
bed and banks of river - 50Hydraulic radiusRatio of the cross sectional area
of the channel and the length of
its wetted perimeter - 51HydrographGraph showing the discharge, depth and velocity of a given point of a stream at a particular time (normally during a storm)
- 52InfiltrationDownward movement of water into soil
- 53Infiltration rateSpeed (mm/s) at which water passes through ground into soil
- 54InterceptionPrevention of precipitation reaching Earth's surface by trees and vegetation
- 55Interception storageTotal volume of water held on
surface of vegetation - 56Knick pointBreak of slope in the long profile. Often upper limit which downcutting from rejuvination has reached. Marked by rapids/waterfalls
- 57Lateral erosionMiddle/lower sections where river has high energy especially if close to bankfull. Widens valley, especially strong on meanders, where hydraulic action undercuts river cliffs
- 58LeveesNatural ridge formed by deposition of coarse material along channel edge.
- 59Lining the channelLining river with concrete, making it smoother and reducing friction, allowing water to flow faster
- 60LoadMaterial carried by river
- 61MagnitudeSize of the food
- 62MeandersBends in a river formed by helicoidal flow, with erosion on the outside and deposition on the inside
- 63NaturalisationRestoring rivers to a more natural state by removing hard engineering
- 64Overland flowMovement of water over surface of land, usually when ground is saturated or frozen
- 65Peak rainfallTime when maximum amount
of rain was falling - 66PercolationGravity flow of water seeping
into soil or rock - 67Point barSediments laid down on the
inside of a meander - 68PotholesFormed by abrasion, pebbles carried by flow get stuck in crack, an eddied is formed and the pebbles grinds down in circular motion to form pothole
- 69PrecipitationAll moisture that reaches the Earth including rain, snow and dew
- 70ProfileChanging height of a river from source to mouth, also called long profile
- 71RapidsStretches of fast flowing water over rock and shallow riverbed
- 72RealignmentStraightening/shortening of river course by removing meanders, increases gradient making water move faster
- 73RegimeAnnual pattern of river discharge
- 74RejuvinationRenewal of energy permitting accelerated erosion and transport. Rivers adjusting to new base level
- 75River cliffOutside of a meander,
steep undercut bank - 76River restorationReturning uplands to peat bog increasing absorption in soil
- 77RoundnessShape of sediment in a river, changes downstream as a result of attriction
- 78RunoffWater flowing over land surface as channel flow/overland flow
- 79SaltationSmall stones bounce along channel bed
- 80SinuosityCurving nature of a meander.
Actual channel length divided by
straight line distance - 81Sluice gatesBarriers that hold water back, some pump water in opposite direction
- 82Soft engineeringFlood management strategies that are non-structural, more 'natural'
- 83Soil moistureTotal amount of water, including water vapour in unsaturated soil
- 84Solution loadDissolved minerals transported within mass of moving water
- 85StemflowFlow down plant trunks/stems
following interception. - 86StormflowWater that reaches the channel through runoff. Combination of overland flow and rapid throughflow
- 87StrataLayers of rock
- 88Surface storageTotal volume of water on
surface in lakes etc - 89SurplusMore than is needed
Eg. Soil moisture - 90Suspended loadBulk of sediment transported by river. Reason most rivers are brown
in colour in bankfull - 91ThroughflowMovement of water downslope
within soil layer - 92TractionLarge stones rolled along river bed
- 93UrbanisationIncrease in proportion of countries population living in urban areas
- 94VelocitySpeed and direction at which a body of water moves (m/s)
- 95Verticle erosionDominates upper reaches of river cutting into bed by abrasion and hydraulic action
- 96Water budgetRelationship between inputs and outputs in drainage basin, shown as graph
- 97Washland restorationWet lands allowed to flood at times of high discharge, to reduce impact elsewhere
- 98WaterfallsSteep or verticle part of the river, occur when hard rock lies across the river with soft rock downstream which erodes faster
- 99WatershedBoundary between two drainage basins, usually ridges of high land
- 100Water tableSurface of saturated layer of soil/rock
- 101Wetted perimeterPortion of perimeter of a stream channel cross section that is in contact
with the water
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