Rivers Flashcards
What is a source?
The start of the river
What is a mouth?
The end of the river
What is a tributary?
A small river that flows into a bigger river
What is a confluence?
A place where 2 rivers join
What is a estuary?
The section of the river near the mouth that is tidal
What is a drainage basin?
The area of land that drains into a river and its tributaries
What is a watershed?
The dividing line between 2 drainage basins
What is a river long profile?
The course a river takes from the source to the mouth. Often split into the upper and lower course
What is a bed?
The bottom of the river channel
What is a bank?
The sides of the river
What is a wetted perimeter?
The length of the bed and the banks in contact with the river
What is a channel?
The route course that the river flows
What is a thalweg?
The fastest part of the river
What are the 4 river processes?
Corrasion
Attrition
Solution
Hydraulic action
What is corrosion/solution?
The process of water dissolving a rivers’ load as well as the bed and banks
What is corrasion/abrasion
The process of the rivers’ load crashing and rubbing into the river banks
What is hydraulic action?
Water and air getting into cracks in a river bank
What is attrition?
Load crashing into each other in a river
What type of erosion is there more of at the upper course of a river?
Vertical erosion
What type of erosion is there more of at the lower course of a river?
Horizontal erosion
What are the 4 main ways a river transports a load?
Traction, saltation, suspension, solution
What is traction?
The process of large pieces of load rolling along a river bed
What is saltation?
The process of load bouncing along the river bed
What is suspension?
The process of smaller particles joining the river flow
What is solution?
The process of minerals being dissolved into water
What is deposition?
When a river doesn’t have enough energy so it starts to deposit its load
What is the discharge of a river?
The amount of water being carried by a river
What is an open system?
Where water can be added or lost
What is a closed system?
Where water can’t be added or lost
What are the 4 stages of the water cycle?
Evaporation -> Condensation -> Precipitation -> Repeat
What is precipitation?
Any moisture that falls from the sky
What is infiltration?
When water travels from the surface of the earth into the ground
What is surface run off?
When water travels across the surface of the earth
What is channel flow?
Water that is travelling in rivers or streams.
What is stem flow?
When intercepted water then travels down the branches and trunks of vegetation.
What is percolation?
When water travels from unsaturated ground into saturated ground.
What is groundwater flow?
The movement of water through saturated ground.
What is throughflow
The movement of water through unsaturated ground.
What is a canopy drip?
Intercepted water dripping off vegetation onto the ground.
What is interception?
When an object (building, tree) stops precipitation reaching the ground beneath.
What is surface storage?
Any water that is held on the surface of the earth e.g. lake or pond. Some surface stores like puddles may only be temporary.
What is soil-moisture storage?
Water that is stored below the surface in unsaturated ground.
What is groundwater storage?
Water that is stored in saturated ground.
What is evaporation?
Liquid turning into water vapour
What is transpiration?
Liquid water evaporating from vegetation.
What is saturated soil?
Soil that can’t hold anymore water
What is unsaturated soil?
Soil that still has space for water between its pores
What is the water table?
The line between saturated and unsaturated soil
What is condensation?
When water vapour cools and condenses and turns into water
What is permeable?
A surface that will allow water through it
What is non-permeable?
A surface that will not allow water through it
What is porous?
An object that can hold water
What is non-porous?
An object that can’t hold water
What are some human impacts on the water cycle?
Deforestation, urbanisation, irrigation, agriculture, industry, transport, dams
How does deforestation affect the water cycle?
Less interception -> less stem flow and canopy drip. More surface run off and higher flood risk
How does urbanisation affect the water cycle?
In permeable surfaces are created -> less infiltration and more surface run off. Buildings can also intercept water
How does agriculture affect the water cycle?
Uses large amounts of water -> Reduce amounts of river water. Can also pollute water -> Eutrophication
How does industry affect the water cycle?
Big user of water -> Reduces amount of river water. Chemicals and water is also dumped into rivers
How does transport affect the water cycle?
Ports need to be built for ferries, oil spills and noise can also disturb marine life
How do dams affect the water cycle?
Reduce velocity and discharge of rivers
State some river land forms that occur at the upper course
Waterfalls, rapids, V-shaped valleys, interlocking spurs and gorges
State some river land forms that occur at the middle course
Meanders, oxbow lakes, levees
State some river land forms that occur at the lower course
Deltas, floodplains, meanders, oxbow lakes
Name some land forms which are formed by erosion
Waterfalls, rapids, gorges, potholes, V-shaped valleys
Name some land forms which are formed by deposition
Deltas, levees
Name some land forms which are formed by erosion and deposition
Meanders, oxbow lakes, floodplains
What is a waterfall?
An area where water descends vertically
State some benefits of living near a waterfall
Beauty, tourism, jobs, HEP
What is a gorge?
A deep sided valley left behind when a waterfall retreats
State some disadvantages of living near a waterfall
Drowning, transport links, overcrowding and pollution,, navigation
State the 5 processes of a retreating waterfall
Undercutting soft rock Overhang of hard rock collapses Plunge pool develops Waterfall retreats upstream creating gorges Repeat
What is a distributary?
A small river that breaks off from the main river in a delta
What is flocculation?
The process of particles joining together
What is a meander
A curve in the river due to one side of the river flowing faster than the other
What is a slip off slope?
Formed on the side of the river with the greatest deposition
What is a river cliff
A steep sided bank
How are oxbow lakes formed?
When 2 meanders join or the “neck” of one gets cut off due to deposition
How are floodplains created?
The constant horizontal erosion of meanders
What is alluvium?
A mineral rich load deposited on floodplains
What is bankfull discharge?
When a river channel is full and can’t hold anymore water
What is a bluff line?
The outer limits of the floodplain
What is a strand line?
The line of material left behind after a river has flooded
What are types of flood protection?
Hard engineering, soft engineering
State some examples of hard engineering
Levees, flood barriers, flood control channels, dams
What are some advantages and disadvantages of levees?
Increases cross-sectional area -> Can hold more water before it flood
Ugly and expensive
What are some advantages and disadvantages of flood barriers?
Form a physical barrier designed to stop storm surges
Very very expensive
Ugly
Liable to bust depending on quality
What are some advantages and disadvantages of flood control channels?
Concrete channels that may run above or below the surface. Used when the river is about to reach bankfull discharge
Ugly
Expensive
What are some advantages and disadvantages of dams?
Regulate river flow and river never exceeds bankfull discharge
Sometimes ugly
Very expensive
What is hard engineering?
The building of physical and permanent structures
What is soft engineering?
Working with nature to reduce flooding
State some examples of soft engineering
Reforestation, sandbags, temporary flood barriers, land use, controlled flooding
What are some advantages and disadvantages of controlled flooding?
Cheap and protects more valuable areas
Land becomes unusable and river floods
What are some advantages and disadvantages of reforestation?
Increases “lag” time by intercepting precipitation, cheap
Trees take a while to grow
What are some advantages and disadvantages of sandbags?
Cheap, forms some protection
Not flood-proof and water can still get through
What are some advantages and disadvantages of temporary flood barriers?
Stops water damaging property
Ugly
What are some advantages and disadvantages of land use?
Areas of high value won’t be built on hazardous ground
Aren’t really any
What is a flash flood?
A flood that arrives with little notice
What is relief?
The shape of the land