Water on the Land

Question 1

What is discharge and what’s it measured in?

Answer 1

The amount of water in a river measured in cubic metres per second (m^3/sec).

Question 2

What 6 factors affect the amount of discharge?

Answer 2

Rainfall (type/amount), temperature, previous weather (wet/dry), relief (steep/gentle), rock type (permeable/impermeable), land use (rural/urban).

Question 3

Why does discharge usually increase from source to mouth?

Answer 3

Tributaries add water to the main channel so the width and depth increases.

Question 4

What is velocity and what’s it measured in?

Answer 4

The speed of the river measured in m/s.

Question 5

Why does river velocity increase form source to mouth?

Answer 5

As discharge increases, there’s less frictions from the bed and banks. Water can flow faster (even though gradient becomes gentler).

Question 6

What are the 4 erosion processes of rivers?

Answer 6

Hydraulic action, abrasion, attrition, corrosion.

Question 7

What are the 4 ways a rivers load can be transported?

Answer 7

Traction, saltation, suspension, solution.

Question 8

Deposition occurs when the river slows down and energy is lost. When are the 3 times this happens?

Answer 8

On the inside bends of meanders, where the channel widens and at the mouth.

Question 9

Is the heaviest material (boulders) deposited last and the lightest (clay) last? Also, wha happens to the solution?

Answer 9

Yes.

Minerals in solution becomes salt in the sea.

Question 10

What is a long profile and what’s it divided into?

Answer 10

A cross-section of a river from its source to mouth.

Divided into upper, middle and lower courses.

Question 11

Describe a rivers usual gradient.

Answer 11

Decreasing gradually downstream.

Question 12

Long profiles are usually concave, but what can make gem irregular?

Answer 12

Different rock types.

Question 13

Describe the upper, middle and lower course of the cross-profile.

Answer 13

Upper: River erodes vertically to form narrow steep-sided V-Shaped valley. Bedload is angular boulders.

Middle: Begins to erode laterally. Valley widens w/ gentler slopes. Bedload is round pebbles.

Lower: Lateral erosion. Deposition forms wide valley w/ flat valley floor. Bedload is sand, silt, clay.

Question 14

What is drainage basin?

Answer 14

Area of land drained by a river and its tributaries.

Question 15

What is a watershed?

Answer 15

An area of high land separating 2 drainage basins.

Question 16

What is a tributary and confluence?

Answer 16

Tributary is a smaller river joining a larger one. Confluence is the place where the 2 join.

Question 17

Define waterfall, where do they occur and what is its formation?

Answer 17

It’s a place where water flows vertically usually occurring in the upper course where different rocks are.
Soft rock erodes quicker>undercuts hard rock so it overhangs>overhang collapses into plunge pool>water runs over.

Question 18

Describe the formation of an ox-bow lakes and what happens after.

Answer 18

Narrow neck of land within a meander erodes when there’s high flow>meander loop gets bigger and more circular>river breaks the loop off so the water follows the main flow.
Over time lake becomes a marsh then dries up.

Question 19

What’s a flood plain and where are they formed?

Answer 19

An area of flat land either side of a river. Formed in lower course where valley is widest.

Question 20

Describe leeves and their formation.

Answer 20

Raised banks of sediment either side of river channel.
Over years of flooding, the thinner load deposits on outer parts of flood plain while largest sediment deposits at channel edges. This builds up.

Question 21

Name the 3 physical causes or fiver floods and 2 human.

Answer 21

Phys: prolonged rain=short heavy rainstorm, snow melt, steep slopes w/ narrow valleys.

Hum: deforestation, construction of urban areas.

Question 22

Describe a hard engineering method of flood management and 2 soft engineering methods.

Answer 22

Hard: Dams - Built in upper valley to create reservoir so water flow is controlled.

Soft: Flood-plain zoning - Restrict building in areas at risk of floods.
Flood warnings - Gives time to flood-proof houses, move possessions upstairs, evacuate.

Question 23

Outline the Kielder Water reservoir case study.

Answer 23

UK 1982, 12km long, 50m deep, £170mill to build.
Benefits: hydro-elec. power station using water from reservoir, unique plants & animals, water shortages, millions of trees>forest employs hundreds, flood prevention, tourism.
Probs: changes landscape, affects habitat, potential for erosion downstream, re-housing, thousands of acres lost, monoculture trees.

Question 24

Outline the 3 Gorges dam case study.

Answer 24

East China, built to provide electricity, 30+ tributaries.
Positives: Social (reduced flood risk, hydro-elec. energy to millions), Environmental (replaces coal power stations that pollute & help climate change), Economic (saves money for electricity).
Negatives: Social (millions re-housed, damaged homes), Environmental (increase downstream erosion, landslides), Economic (most expensive dam, dredging needed for sediment accumulation).

Question 25

Outline the Boscastle flood case study.

Answer 25

MEDC. Happened Aug 2004.
Causes: Storms brought 80mm of rain in 2 hours.
Impacts: 100 airlifted to safety, properties flooded, cars washed to sea, £300mill damage.

Question 26

Outline the Bangladesh flood case study.

Answer 26

LEDC. South Asia where 3 rivers run through.
Causes: high temp>snow melt, sea level rise, high rainfall in Sep, rivers can spread across flat land, raised river beds, building on flood plain increases run-off.
Effects: 600 dead, millions homeless, 60% land submerged, destroyed crops & infrastructure worth billions, diarrhoea
Responses: supplies & shelter distributed, flood warnings now, water aid, embankments (walls) built.

Question 27

Outline the Storm Desmond case study.

Answer 27

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