river landscapes

Question 1

what is a drainage basin

Answer 1

Area of land drained by a river and its tributaries

Question 2

What do you call the edge of the river basin?

Answer 2

Watershed

Question 3

Confluence versus tributary

Answer 3

tributary: small stream which joins
Confluence: where it joins

Question 4

Vertical versus lateral erosion

Answer 4

vertical is downward
Lateral is the sides

Question 5

Three features found in the upper course

Answer 5

interlocking spurs
Water fall
Gorges

Question 6

how do interlocking spurs form?

Answer 6

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

Question 7

how do waterfalls form?

Answer 7

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

Question 8

how do gorges form

Answer 8

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

Question 9

which landforms are in the middle course?

Answer 9

Meanders and Oxbow Lakes

Question 10

features of meanders

Answer 10

Rivercliff
Slip off slope
Thalweg
Undercutting
Lateral erosion

Question 11

how do Oxbow lakes form?

Answer 11

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

Question 12

What landforms are in lower course?

Answer 12

Flood planes and levees and estuaries

Question 13

What is a floodplain?

Answer 13

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

Question 14

Features of flood plains

Answer 14

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

Question 15

How did levees form?

Answer 15

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)

Question 16

Features of estuaries

Answer 16

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

Question 17

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

Answer 17

infiltration
Throughflow

Question 18

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

Answer 18

Percolation

Question 19

Where does water go after percolation?

Answer 19

Groundwater and then groundwater flow

Question 20

how does precipitation evaporate without touching the ground?

Answer 20

Interception from plants, evapotranspiration

Question 21

three physical factors that can increase flood risk

Answer 21

• 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

Question 22

Two human factors that increase flood risk

Answer 22

• urbanisation – creates impermeable surfaces
• deforestation – prevents interception

Question 23

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

Answer 23

Lag time

Question 24

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

Answer 24

Rising/falling limb

Question 25

For examples of hard engineering to control flooding

Answer 25

dams and reservoirs Channel straightening raising Embankments Flood relief channels

Question 26

pros and cons of dams and reservoirs

Answer 26

- regulates flow and reduces flood risk - multi purpose: HEP, water supply - expensive - requires flooding of large area for reservoir

Question 27

pros and cons of channel straightening

Answer 27

- cutting through meanders to speed flow - increased risk downstream - often lined with concrete: damage habitat, unattractive

Question 28

raising embankments pros and cons

Answer 28

- more capacity - sometimes concrete used: damage habitat, unattractive

Question 29

flood relief channels pros and cons

Answer 29

- redirects excess water during high flow - sometimes concrete: damage habitat, unattractive

Question 30

Three examples of soft engineering to control flooding

Answer 30

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

Question 31

floodplain zoning pros and cons

Answer 31

- high risk areas can be left for recreation, as it does not require construction or changing of land - construction creates impermeable: promotes flooding - difficult to implement on already developed land

Question 32

afforestation pros and cons

Answer 32

- interception - relatively cheap - habitat & mitigation

Question 33

river restoration pros and cons

Answer 33

- opposite of straightening. - if too much flooding downstream, natural features restored, eg meanders - relatively cheap, encourages biodiversity

Question 34

why does Banbury need flood management schemes?

Answer 34

History of flooding including £12.5 million damage in 1998

Question 35

Features of Banbury flood storage

Answer 35

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

Question 36

pros of banbury

Answer 36

- raised motorway stays open during flood - 400 houses and 70 businesses protected, together at a value over £100 million - material for embankments extracted locally, small reservoir: leisure, habitat