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