Study sets, textbooks, questions
Upgrade to remove ads
AS Level Geography - CIE - Hydrology and Drainage Basins
Terms in this set (74)
Found in the lower course of a river. When a river containing a high sediment load floods, suspended load is carried over the flood plain and is deposited in heaps either side of the channel.
A system in which matter can enter from or escape to the surroundings. Example - a drainage basin
a system in which matter and energy exchanges do not occur across boundaries. Example - the globe
The area of land drained by a river and its tributaries
All streams and rivers which drain an area of land and channels water back to the sea.
Watershed or divide
The perimeter of a catchment area. Marks the boundary between two catchment areas.
The junction at which one river flows into another.
Smaller river or stream flowing into a larger one.
Start of a river system (spring, glacier, meltwater etc)
A point where one measures cumecs (m3/s) discharge/velocity
less likely to flood, takes more time to reach the channel
More likely to flood, takes less time to reach the channel
Inputs into the drainage basin system
Precipitation / Water from the source / Watershed
Outputs from the drainage basin system
Evapotranspiration / Channel run off
Infiltration - through flow
Percolation - Interflow
Ground water flow/ base flow
Zone of aeration
Zone in soil that is not saturated with water and that lies above the water table.
Zone of saturation
The lower zone where water accumulates between small rock particles.
How is discharge calculated?
Water in the channel is measured at gauging stations - the volume (m3) of the velocity (seconds) -> cumecs (cubic metres per second)
Show the changes in river discharge around the time of a storm
A measure of how much of a rock is open space.
A measure of the ease with which a fluid can move through a porous rock.
An underground layer of water - bearing permeable rock. Groundwater stored has and can be extracted from a well. Aquiclude = impermeable rock
After a dry period, the rising of the water table back to normal level.
Any natural situation where water flows from the aquifer to the Earth's surface
A confined aquifer containing ground water that is under pressure. A well drilled into this is called an artesian well.
The movement of water through soil, around soil particles. Only when the 'film' of water becomes too big to resist gravity will percolation occur.
Ability to absorb surface water
Water attracted to the surface of the soil.
Variations in the River system from Source to Mouth
This is the wearing away and removal of material from the bed of the channel.
Power of moving water and its frictional drag on the particles lying on the bed.
The explosive force of air trapped in the cracks of rock.
Particles are scraped along the bed by moving water. Small particles tend to smooth or polish the rock surface.
When minerals in the rock become dissolved and are carried away in solution.
This is the reduction in size of particles as they strike each other and the bed of the channel.
Downward erosion of a river bed, occurs at the upper part of the river as it tries to reach base level quicker.
Sideways erosion by a river on the outside of a meander channel. In the middle and lower stretches of the river.
Factors that determine the amount and rate of erosion in a river.
Lithology / Velocity / Gradient / Channel bed roughness / Hydraulic radius / Volume of water (season)
How a river picks up its load.
Erosion of river channels picks up along the way from hydraulic action. Can come from mass movement of valley sides.
Normally lowland - Large amounts of fine, sand, silt and clay. Sediment suspended in water.
Small particles hop along the bed, they get picked up by a fast eddy flow until they're dropped again.
Large particles rolled along by the force of the flowing water.
Dissolved load derived from limestone and chalk - clear stream.
Capacity (of a river)
A measure of the amount of material it can carry. Generally, a river's capacity increases according to the third power of its velocity.
Competence (of a river)
The largest particle that it can carry for a given velocity. A river's competence increases according to the sixth power of the velocity.
Deposition occurs when...
During a period of low discharge / On the inside of a meander bend / Bursting of banks due to reduction in Hydraulic radius / Load increase after deforestation / When a river enters still water.
Water flowing downwards over smooth surfaces can flow without eddies or meanders - little friction.
Water flowing is subject to friction. Friction slows the water down at the sides whereas the middle water overtakes.
The water corkscrews down a spiralling path of the thalweg. Develops meanders.
Rare as helicoidal flow is usually dominant.
Most rivers meander. Meanders usually occur downstream. Caused by spiralling of water. Not caused by large obstacles.
Contain a large number of islands and bars. Where discharge varies a lot. Often in glacial outwash streams. Discharge decreases allowing sediment to deposit, then when water discharge increase the river splits either side of the sediment - constantly changing.
The measure of how bendy a river is.
Found mainly in the upper course of the river; turbulent flow causes circular eddy currents in the bed which causes the pebbles to rotate. The resultant abrasion drills cylindrical holes into the river bed.
Found mainly in the upper course of the river; band of resistant rock underlying the bed which is incompletely worn down, causing highly turbulent flow which gives white water waves.
Found mainly in the upper course of rivers; where water plunges over the edge of a plateau, where a band of resistant rock lies across the bed of a river. The resistant rock is undercut by erosion of the less resistant rock which underlies it, especially through cavitation creating a deep plunge pool.
Middle and lower course of the river. The thalweg flows between pools in straight sections of a river, and starts to erode the outside of the bend. Hydraulic action and abrasion undercut the outer bank, creating a river cliff. Helicoidal flow results in eroded sediment being trainsferred to the inside of the bend forming a slip off slope from a point bar.
A river feature consisting of islands of sediment deposited in the river channel in its middle course.
Flat land near the edges of rivers formed by mud and silt deposited by floods
Deposits of sand and soil at the mouth of a river. Lower competence.
Fan shaped. (Nile) form when the salinity of the sea is lower, making the river water of similar density.
Bird's foot delta
(Mississippi) form when the sea is extra saline and fresh water carries alluvium further out to sea.
(Tiber) Form where there is a stronger element of longshore drift to pull sediment littorally.
Valley Cross Profiles
In the upper course, where the valley is narrow and steeply V-shaped.
A graph showing the relationship between river velocities and erosion, deposition and transportation
The picking up or sediment by the water.
Pools and riffles
Pools - where the channel bed is eroded more quickly due to softer rock causing deeper, faster flow.
Riffles - More resistant rock + rough channel bed.
Operate together as a simple mechanism to regulate the channel's flow.
Widens and deepens a river channel, altering the shape of the channel. Increasing the capacity and subsequently the efficiency.
This is a type of soft engineering technique. The local council examine the flood risks in different areas and prevent buildings in theses areas (e.g. on a flood plain). This can aggravate the problem of housing shortage but lessens surface run off.
Planting trees to increase interception while reducing surface run off.
Creating conditions that are favourable for the development of wetlands.
Restoring a river that has undergone hard engineering back to its original course.
Sets found in the same folder
CIE A Level Geography Hydrology.
AS Level Geography : Migration
CIE A Level Geography Atmosphere.
population cie geography a level
Sets with similar terms
Chapter 1: The Flow of Fresh Water
Unit 4 - Catchment Hydrology - The Drainage Basin…
Cambridge International A-Level Geography - Rivers
Other sets by this creator
To all my sons
To all my sons
Death and the King's Horseman lines
Other Quizlet sets
Gaby Moss AP Government Flashcards
bio 192 flashcards
Chapter 10 Test -True and False
Cardiology Exam III
Most commonly found item during beach cleanups?
True/False: Permablity refers to characteristics of the rick that enable water to flow through pores/voids. Soils with little or no voids such as clay and slit are defined as "tight soils"
How are warm fronts and cold fronts different?
The flood of the Big Thompson River in Boulder County, Colorado, in 1976 was caused by