Key terms

Infiltration

The movement of water into soil or rock

Percolation

Vertical downward movement of water through soil to bedrock

Throughflow

Lateral (horizontal) movement of water through soil

Baseflow

Slow movement of water, deep down in the soil

Precipitation

Conversion and transfer and transfer of moisture in the atmosphere to the land

Soil storage

Storage of water within the soil layer

Groundwater storage

Water contained below the surface in rocks

Inter-basin transfer

Transport of water between 2 different water basin’s

Evaporation

Liquid turning into a gas

Throughfall

Water falling through gaps in vegetation or that drops from leaves or twigs

Stemflow

Water trickling down along twigs and branches and the main trunk

Water table

The upper layer of the permeability saturated zone within solid rocks and sediments

Aquifers

Rocks that contain significant quantities of water

Springs

Where groundwater flow reaches the earths surface

Evapotranspiration

The combined processes of evaporation, sublimation and the transpiration of the water from the earths surface in the atmosphere

Abstraction

Taking water from a source

Discharge

Quantity of water that passes a given point on the bank of a river within an interval of time. In simple terms, floodwater

Interception loss

The loss of the water that has been intercepted by vegetation

Porosity

Capacity of rock to hold water in its holes

Permeability

Ability to transmit water through a rock via joints and fissures

Overland flow

Flow of water above the surface

Aquiclude

Rock that cannot hold water

Antecedent rainfall

Rainfall that has already fallen

Corrasion and Abrasion

Wearing away of the bed and bank by the load carried by a river

Attrition

Wearing away of the load carried by a river. Banging together

Hydraulic action

Force of air and water on the sides of rivers and in cracks

Cavitation

Force of air exploding under high pressure

Corrosion (Solution)

Removal of chemical ions, chemical erosion

Load

Suspended- carried by river

Saltated- larger load bouncing on bed

Bed (tracted)- load carried along bed

Hjulstrom curve

Relationship between velocity and grain size

Laminar flow

water flowing in sheets or laminae parallel to the channel bed

Turbulent flow

Chaotic flow involving eddying and vertical movement

Helicoidal flow

Corkscrewing motion responsible for the formation of meanders

Pools

Deep parts of a river

Riffles

Deposited bars in the straight section of a meander

River cliffs

Steep banks located on the outer bend of a meander

Point bars

Landforms of deposition found on the inner bank of a meander

Levees

Embankments found at the side of a river, formed by deposition during floods

Floodplain

Any part of any stream valley that is inundated during floods

River bluffs

Steep slopes at the edge of of a river

Bottomset beds

The finer material carried out in a delta, later covered by heavier sediments

Foreset beds

Medium sized deposits in deltas, on top of bottom set

Topset beds

The heaviest deposits in deltas, deposited on top of everything

Arcuate delta

Fan shaped delta, found in areas where regular LSD or other currents keep the seaward edge of the delta relatively smooth in shape

Cuspate delta

Dogtooth shape, formed by regular but opposing gentle water movements

Birds-foot delta

Found where the river brings down enormous amounts of fine silt, deposition can occur in a still sea area, along the edges of the distributaries and extend for a very long distance offshore

Lacustrine delta

A delta in a lake

Sinuosity

The amount of bend in a river

Alluvial fans

When material is deposited when a river gradient decreases and it enters a wide, flat valley

Recurrence interval

Regularity of a flood event

Drainage basin

Total area that contributes water to a river