river landscapes Flashcards

1
Q

what is a drainage basin

A

Area of land drained by a river and its tributaries

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2
Q

What do you call the edge of the river basin?

A

Watershed

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3
Q

Confluence versus tributary

A

tributary: small stream which joins
Confluence: where it joins

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4
Q

Vertical versus lateral erosion

A

vertical is downward
Lateral is the sides

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5
Q

Three features found in the upper course

A

interlocking spurs
Water fall
Gorges

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6
Q

how do interlocking spurs form?

A

Stream in V-shaped Valley (vertical erosion) winds around areas of hard rock

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7
Q

how do waterfalls form?

A

When river flows over hard rock followed by soft rock, soft rock roads quicker (abrasion and hydraulic action)
Step is formed
Force of water under hard rock (hy ac) creating plunge pool
hard rock overhang and eventually collapses
hy ac and attrition a road these fallen rocks which then become transported away by the river

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8
Q

how do gorges form

A

waterfall process repeats and waterfall move upstream, creating an almost vertical valley

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9
Q

which landforms are in the middle course?

A

Meanders and Oxbow Lakes

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10
Q

features of meanders

A

Rivercliff
Slip off slope
Thalweg
Undercutting
Lateral erosion

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11
Q

how do Oxbow lakes form?

A

lateral erosion narrows neck of meander
They connect, meaning water flows mostly in a straight line, and slowly around the redundant loop
This causes lots of deposition in the redundant loop and on the step of slopes until oxbow Lake is cut off
Lake evaporates and leaves meander scar

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12
Q

What landforms are in lower course?

A

Flood planes and levees and estuaries

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13
Q

What is a floodplain?

A

large area of Flatland either side of a river that is prone to flooding

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14
Q

Features of flood plains

A

layers of allurium (& in meander scars)
Levees
Meander migration
River Bluff
meander scar
Oxbow Lake
Reeds and marsh plants

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15
Q

How did levees form?

A

when flow is slow, deposition occurs on the river bed, making it prone to flooding. When this does flood, heavier and corser sediment is deposited as it is more difficult to transport.
finer sediment is carried further on the floodplain
riverbed continues to build bed load, meaning the banks become higher and wider (levees)

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16
Q

Features of estuaries

A

High tidal range
At high tide, rivers cannot flow, velocity Falls, sediment deposits, mudflats, salt
marshes
very wide
tidal bores (waves upstream)

17
Q

What do you call it when water soaks into the soil and flows into the river from the soil?

A

infiltration
Throughflow

18
Q

what do you call it when soil moisture soaks into the rock below?

A

Percolation

19
Q

Where does water go after percolation?

A

Groundwater and then groundwater flow

20
Q

how does precipitation evaporate without touching the ground?

A

Interception from plants, evapotranspiration

21
Q

three physical factors that can increase flood risk

A

• prolonged precipitation, over saturated soil
• geology/rock type – impermeable rocks promote surface run-off to river
• Relief – steep mountainous environments encourage rapid transfer towards rivers

22
Q

Two human factors that increase flood risk

A

• urbanisation – creates impermeable surfaces
• deforestation – prevents interception

23
Q

what do you call the time between peak rainfall and peak discharge on a hydrograph?

A

Lag time

24
Q

what do you call the increase/decrease on a hydro graph

A

Rising/falling limb

25
Q

For examples of hard engineering to control flooding

A

dams and reservoirs
Channel straightening
raising Embankments
Flood relief channels

26
Q

Three examples of soft engineering to control flooding

A

floodplain zoning (restricting land uses to certain zones on floodplain)
Afforestation
River restoration

27
Q

why does Banbury need flood management schemes?

A

History of flooding including £12.5 million damage in 1998

28
Q

Features of Banbury flood storage

A

2.9 km embankment - reservoir now where material was taken
This created a flood storage area

29
Q

One social one economic and one environmental benefit of Bandberry scheme

A

• raised motorway stays open during flood
• over 400 houses and 70 businesses protected
• Material from embankments was extracted locally - small reservoir