Water On The Land Flashcards
What are water stores? Give some examples of them.
Different places where bodies of water are naturally stored. Lake/pond Rivers Underground Sea/oceans Glaciers/ice caps
What is a drainage basin?
A drainage basin is an area of land drained by a river and its tributaries.
What are the four ways rivers can erode?
Hydraulic action: the sheer force of the flowing water on the bed and banks.
Abrasion: stones carried by the river wear away the channel (sandpaper effect).
Attrition: stones collide, wearing them away, becoming smaller and rounder.
Corrosion: slightly acidic river water dissolves soft rocks.
How is material transported by the river?
Traction: stones are rolled along the river bed by the force of flowing water
Saltation: stones ‘bounce’ along the river bed.
Suspension: particles of still clay float in the waters, making the river look cloudy.
Solution: mineral dissolve in the river water.
What is discharge?
Discharge is the amount of water in a river, it’s measured in cubic meters per second. Discharge usually increases from source to mouth because tributaries add water to the main channel. As the discharge increases, the width and depth also increase.
What is velocity?
Velocity is the speed of the river. It’s measured in metres per second. River velocity usually increases from source to mouth. This is because the discharge increases, there’s less friction from the bed and banks. This means the water is able to flow faster, even though the gradient becomes gentler.
List some features of a river basin and a river.
Watershed: an area of higher land separating two drainage basins
Source: the place where the river begins
Tributary: a smaller river joining a larger river
Confluence: the place where two rivers join
Meander: a bend in a river
Mouth: the place where the river enters a lake or sea
Describe what happens at each point through a river linking to a valley cross-profile.
Upper corse: the river erodes vertically to for, a narrow v-shaped valley. It has steep valley sides and its bed load is s gulag bounds and cobbles.
Middle course: the river erodes vertically and laterally and the valley widens. The river has gentle sloping called sides and its bed load consists of round cobbles and pebbles.
Lower course: the river erodes laterally and deposits to form a wide valley with a flat valley floor . Its bed load consists of sand, silt and clay.
How are waterfalls formed?
They occur where a band of harder rock overlays a band of soft rock. Softer rock rock erodes quickly, undercutting harder rock.
Harder rock erode more slowly, forming an overhand.
Overhand eventually collapses,vehemently waterfall retreats upstream
A gorge is formed due to the steep sided valleys
Plunge pool erodes under waterfall.
How are ox-bow lakes formed?
Narrow neck of land is eroded, meander loop becomes large and inefficient.
River breaks through to follow shortest course.
Meander is cut off to form an ox-bow lake. Overtime the lakes becomes a marsh, then dries up.
What are flood plains and how are they formed?
A flood plain is an area of flat land formed on either side of a river. Flood plains are formed in the lower course of a river due to a combination of erosion and deposition.
Whenever there is a flood from a river it deposits material that raises the valley floor.
What are levees and how are they formed?
Levees are raised banks of deposited sediment formed on either side of a river channel.
Levels are formed during many years of river flooding, when the largest material is deposited next to the river.
Give some examples of hard engineering for management of rivers.
Storage areas
Dams
Flood walls
Straightening and depending a river
What is water surplus?
More water than needed in a specific area
What is water deficit?
Not enough water needed in a specific area.
