Geo Physical Key Terms Flashcards
Solution Load
Solution load is the dissolved sediments that are the product of solution weathering.
Suspension Load
Suspension load is sediment that is light enough to be suspended within the body of the flowing water. Could be shown diagrammatically.
Helicoidal Flow
Helicoidal flow is a type of corkscrew flow which moves across a meander.
Laminar Flow
Laminar flow is a smooth slow velocity movement of water over a smooth surface.
Discharge
Discharge is the volume of water passing a given point in a unit of time (cumecs) Can be defined as:
Q = AV
Velocity
Velocity is the speed of flow usually measured in metres per second. Measured by taking the average over a particular distance. It is a function of channel slope and hydraulic radius.
Water Table
The water table is the upper surface of the zone of groundwater saturation.
Groundwater Recharge
Groundwater recharge is the action by which water is added to the water table (aquifer) after losses to channel, etc.
Groundwater
Groundwater is percolated water that is held below the water table (phreatic water)
Springs
Springs are flows of water where the water table intersects with the surface
Infiltration
Infiltration is the movement of water downwards from the surface into the soil.
Percolation
the downward movement of water under gravity through the pores, joints etc. of a permeable rock.
Hydraulic Action
It is the force of the water hitting the side of the river. The particles are thus dislodged from the river bed. It can also lead to the compression of air in cracks which subsequently weakens them.
Solution (erosion)
Solution is related to the chemical composition of the water and happens continuously. It is a chemical action which dissolves carbonate rocks such as limestone.
Abrasion
Abrasion is the erosion of the channel banks and bottom by coarse and angular fragments of hard rock. This may produce pot holes.
Traction
Traction is a means of the transportation of sediment such that larger load (e.g. pebbles or cobbles) are rolled or pushed along the stream bed by the current.
Suspension
Suspension is sediment transportation whereby light sediments (grains etc.) are suspended above the bed by the current.
Lag Time
Lag time is the time between the peak rainfall and the peak discharge on a hydrograph.
Rising Limb
Rising limb is the part of the discharge curve that shows the rise of discharge from the onset of the precipitation until peak discharge is reached.
Interception
Interception is the capture of precipitation by leaves, branches, etc of trees and vegetation. The water may then be evaporated or reach the ground as drip or stem flow.
Through Flow
Through flow is the lateral downslope movement of water within soils after it has been infiltrated into the soil.
Riffle
Pools are relatively deeper areas excavated in the channel bed where the current flows slower.
Pool
Riffles are shallow, gravel areas in the channel causing more friction to the current, with steeper slope and faster flow.
Stem Flow
Stemflow is the progression of intercepted precipitation down the stems and trunks of vegetation.
Turbulent Flow
Turbulent flow consists of a series of eddies, both vertical and horizontal, in a downstream direction. Turbulence varies with the velocity of the river and depends on the energy available after friction has been overcome.
Overland Flow
Overland flow is movement of water across the surface of the ground or downslope. Only definitions are required and not a detailed explanation.
Saltation
Saltation is the hopping or bouncing motion of smaller material. Both the form of movement and material size are required for two marks each.
Surface Storage
Surface storage is water that has not infiltrated the surface and is stored on the surface in the form of puddles
Groundwater Storage
Groundwater storage is percolated water that is held within the aquifers below the water table.
Entrainment
Entrainment is the process whereby sediment is picked up by the channel flow and is dependent upon the balance between the velocity and size of particle.
Porosity
Porosity depends on the texture of the rock and the size, shape and arrangement of its mineral particles. Areas between the particles are called pore spaces and their size and alignment determine how much water can be absorbed and stored by the rock. Porosity is usually greatest in rocks which are coarse-grained such as gravels, sands.
Permeability
Permeability is the rate and ease with which water may be transmitted within a rock or the rate with which is able to pass through it.
Throughfall
Throughfall is the movement of precipitation through the branches and leaves of trees and vegetation to the earth’s surface.
Peak Discharge
Peak discharge is the time when the river has its maximum amount of flow/ volume of water
Antecedent Moisture
Antecedent moisture is moisture in the soil that is retained after a period of rainfall.
Evapotranspiration
Evapotranspiration is the combination of moisture loss due to evaporation (liquid to gas) and transpiration from the stomata of vegetation.
Baseflow
Baseflow is the discharge into a stream from the ground water store, especially sustaining flow between rainfall events.
Thalweg
The thalweg is the line of maximum velocity/flow along a river channel.
Recharge
Recharge is the refilling of the zone of saturation by water (percolated) following a period of draw down occasioned by lack of water or increased water abstraction.
Solution (transport)
water acting as a solvent (dissolving), most effective when acidulated such as carbonation / limestone, or transported in the river as a solute load.
Shortwave radiation
Short wave radiation is incoming solar radiation.
Longwave radiation
Long wave radiation is outgoing terrestrial radiation whereby the earth’s surface has been heated by solar radiation
Sublimation
Sublimation is the change of state from a solid to a gas (usually ice to water vapour) without going through the liquid phase. It is also used for the reverse process.
Sensible heat transfer
Sensible heat transfer is the transfer of heat by conduction or convection.
Earth (terrestrial) Radiation
Earth radiation is the radiation emitted by the earth body as long wave radiation.
Incoming Solar Radiation
The energy emitted from the sun that reaches the earth as short-wave radiation.
Evaporation
Change of state from (water) liquid to gas as a result of heat.
Oragraphic Uplift
the forced uplift of air on meeting a topographic obstacle such as a mountain front.
High Pressure
High pressure is an area of descending air (high level convergence) that increases pressure (isobars) at the surface.
Relative Humidity
Relative humidity is the amount of moisture in the atmosphere expressed compared to the maximum amount of moisture that can occur.
Condensation
Condensation is the cooling of air to the dew point
Absolute Humidity
Absolute humidity is the mass of water vapour which is present in the air at any one time.
Latent Heat
Latent heat is the amount of heat energy needed to change the substance from say a liquid to a gas or the heat released when a gas condenses into a liquid.
Convection
Convection is when air is warmed during the daytime and rises in pockets as thermals. As air expands, it uses energy and loses heat and the temperature drops. Air is cooled by reduction of pressure with height.
Dew
Dew is water in the form of droplets, caused by condensation or cooling on exposed surfaces.
Temperature Inversion
A temperature inversion is when temperature rises rather than falls with altitude.
Fog
Fog is the suspended water droplets producing Fog of visibility less than 1 km.
Humidity
Humidity is the water content of the atmosphere and can either be absolute or relative humidity.
Low Pressure
Low pressure is an area of ascending air (often associated with convectional heating) and hence low pressure (isobars) at the surface.
Hydrolysis
Hydrolysis is a weathering process where hydroxyl ions (acidulated water) in water attack minerals such as feldspar in granite.
Carbonation
Carbonation refers to the process whereby carbon dioxide is dissolved in water to produce carbonic acid, which can then attack the calcium carbonate/limestone.
Hydration
Hydration is a weathering process where minerals absorb water into their structure, causing them to swell and to become vulnerable to breakdown.
Freeze-thaw
Freeze-thaw is the process whereby water enters pores and cracks in rock then freezes and expands and subsequently thaws.
Island Arcs
Island arcs are volcanic landforms created by the subduction of one ocean plate beneath another, followed by upwelling of magma.
Pressure Release
Fractures created in rocks due to removal of pressure
Slide
Slide is movement of material along a defined slide plane with little internal deformation/en masse.
Flow
Flow is the movement of water-laden material with internal deformation.
Salt Crystal Growth
Crystal growth is development of salt crystals in pores, cracks in rock which then put pressure on the rock structure.
Ocean Ridges
Ocean ridges are ridges of magma at divergent plate boundaries under oceans. For both marks, answers will need the plate boundary and lava.
Island Arcs
Island arcs are chains of volcanoes where two oceanic plates meet. For both marks answers will need volcanic chains where two oceanic plates meet.
