Water On The Land Flashcards
Alluvium
Rock particles (clay, silt, sand, gravel) deposited by a river
Attrition
Erosive process where particles of load and knocked about as they are transported and gradually become more rounded/reduced in size
Base level
Altitude of the mouth of the river and point where the gradient becomes zero. No further erosion possible during normal river flow at this point
Bed load
Material carried by a river by being bounced or rolled along it’s bed
Channel
Course for the river water (straight or meandering)
Condensation
When water vapour changes to liquid
Confluence
Point at which 2 or more rivers meet
Cross profile
Shape of a slice across a river
Deforestation
Removal of a forest/stand of trees where land is thereafter converted to a non-forest use
Delta
River mouth choked with sediment causing the main channel to split into smaller branching channels or distributaries
Depth
Measurement of the distance between the bed of the river and surface. Increases downstream (joined by lots of tributaries)
Discharge
Volume of water passing a specific point at a given time. Becomes larger downstream (many tributaries join). Cross sectional area x velocity (cumecs - cubic metres per second m3/sec)
Drainage basin
Land that is drained by a river and it’s tributaries enclosed by the watershed
River engineering
Steps that can be taken to manage flooding. Often involve trying to lengthen amount of time it takes for water to reach river channel (increasing lag time). Can be hard or soft
Erosion
Wearing away of bed and banks of river channel by abrasion, hydraulic action, solution and attrition
Estuary
The tidal mouth of a river with large flat expanses of mud exposed at low tide
Evaporation
Water lost from the ground/vegetation surface
Flood plain
Wide, flat floor of a river valley. It consists of fertile sediments (alluvium) deposited by the river during flood conditions
Flood plain zoning
Procedure used to identify areas of varying flood hazard and therefore constructing buildings of high land value away from areas of flood risk
Gorge
Steep-sided narrow rocky valley marking the retreat of a waterfall
Gradient
Slope of river profile, steep close to the source, gradually becoming more gentle until the river reaches sea level
Groundwater
Water stored in rock beneath the surface
Groundwater flow
Water flowing through the rock layer parallel to the surface
‘Hard’ options
River management that tends to be more expensive and have a greater impact on the river and the surrounding landscape (forceful human intervention)
Hydraulic action
An erosive process where the sheer force of the water by itself can erode material from the bed and banks of the river channel
Infiltration
Water sinking into soil from the ground surface
Interception
Water being prevented from reaching the ground by trees or other vegetation. A store of water
Interlocking spurs
As the river descends from the highland it begins to meander between spurs which interlock down the valley
Lateral erosion
Erosion by a river on the outside of a meander channel. It eventually leads to the widening of the valley and the formation of the flood plain
Levées
River embankments built by deposition as the river floods (natural or man-made)
Load
The material transported by a river as bedload, suspended load or dissolved load (in solution)
Long profile
A slice through the river from source to mouth