Geography - Drylands

Question 1

Diversity of drylands…

Answer 1

Rocky mountains, lake beds, river valleys or desert plains…

Question 2

How many inhabit drylands?

Answer 2

2 billion.

Question 3

Properties of dry lands?

Answer 3

Precipitation is weak and erratic annually, with arid areas.

Question 4

Potential Evapotranspiration

Answer 4

The amonut of transpiration that would occur if there was a sufficient water source

Question 5

When is there deficient moisutre?

Answer 5

When PET exceeds p

Question 6

Types of arid envrionment…

Answer 6

Hyper-arid
Arid
Semi-arid
Dry-subhumid

Question 7

Hyper-arid

Answer 7

True deserts with a P/PET value of less than 0.05

Question 8

Examples of hyper-arid deserts?

Answer 8

Central sahara, Arabian peninsula and Namib deserts.

Question 9

Arid

Answer 9

Classified as between 0.05 and 0.2, with 200mm annual rainfall

Question 10

Semi-arid

Answer 10

Between 0.2 and 0.5, with 500mm rainfall in winter and 800m rainfall in the summer.

Question 11

What does varying precptiation effect?

Answer 11

Agriucltural practices, huamn welfare, drougth susceptibiltiy

Question 12

Dry-subhumid

Answer 12

Areas between 0.5 to 0.65

Question 13

What causes aridity?

Answer 13

Subtropical regions
Intercontinentiality
Mountain Shadow Effect
Western Coastlines

Question 14

Mountain Rain Shadow Effect

Answer 14

A patch of land that desertifies due to mountain rnage blocking plant growing, rainy weather.

Question 15

Example of cause of aridity?

Answer 15

Sahara is subtropical, intercontinental and affected by the Tibesti Massif mountains

Question 16

Why are Central Asia and North America Arid in places?

Answer 16

Continentality so weather systems cannot penetrate these area

Question 17

Example of currents affecting aridity…

Answer 17

Namib and Atacama deserts affected by Antartic cold ocean currents, bringing colder cliamtes to these regions supressing sea surface evaporation and rainfall.

Question 18

Example of seasonal variations of aridity…

Answer 18

Closer to the ITCZ then more susceptible to its movements and rainfall varaitions.

Question 19

What are the types of soil?

Answer 19

Aridisoil
Alfsol
Entisoil
Mollisoil
Vertisol

Question 20

What causes soil crusting?

Answer 20

High evaporation with icnreased mineral concentraiton that dry and form hard layers

Question 21

How do biological crusts form?

Answer 21

Algae and Cyanobacteria with silica and calcium carbonate.

Question 22

Hydrophytes

Answer 22

Wetland plants tolerating permenently saturated soils, foudn in very few drylands.

Question 23

Mesophytes

Answer 23

Tolerate 10-20% soil moisture, measured between its fiedl capaicity and wilting point

Question 24

Xerophytes

Answer 24

Can tolerate extreeme moisture deficieny with little as 5% moisture

Question 25

How plants adapt to arid areas?

Answer 25

Regulate dormancy and limitation of growth and reproduction to the wet seasons.

Question 26

What plants are found in deserts?

Answer 26

Rarely 10% cover, contain shrubs and grasses

Question 27

What geographical sturctures influence drylands?

Answer 27

Tectonic activity and morphology like mountainous areas or flatlands.

Question 28

Rock weathering in drylands..

Answer 28

High ET means higher mineral/salt concentration as well as the bare rock surfaces

Question 29

Most common forms of weathering in arid areas?

Answer 29

Insolation and thermal weathering

Question 30

Granular Disaggregation

Answer 30

The detachment of minerals due to stress of intercrystalline bonds being weaker than the intracrystalline bonds.

Question 31

Salt Weathering

Answer 31

This is where high precipitaiton causes high salt concentration in tnadem with limited leeching

Question 32

Why is salt crystallization favoured with higher temperatures?

Answer 32

Moisture induces increased salt volume and thermal expansion of increasing heat.

Question 33

Infilitration Excess Overland Flow

Answer 33

A for of runoff where the surface is bare rock, and can promote surface sealin/crusting inunconsolidated sediments.

Question 34

How does sedimentation occur in drylands despite low precipitation?

Answer 34

High convection and thunderstorms

Question 35

Why do drylands ONLY exhbit low channel formation?

Answer 35

Low catchment and infilitration through the bed.

Question 36

Aeloian Processes

Answer 36

Refers to wind activity and its erosion, tranportation and sediment deposition.

Question 37

Example of aeloian processes?

Answer 37

Sand dunes

Question 38

Types of dune?

Answer 38

Barchan, seif, star dunes and transverse dunes

Question 39

Barchan and Seif dunes

Answer 39

Crescent shaped and Elongated respectively

Question 40

Star dunes

Answer 40

Pyramidal sand mounds with slip faces on three or more arms that radiate from the high centre of the mound.

Question 41

Transver Dunes

Answer 41

Are symmetrical, elongated dunes lying at right angles to the prevailing wind direction