Physical - Deserts

Question 1

Deserts as natural systems:

The concept of a system

Answer 1

A system: the ‘big picture’ of inputs, outputs, transfers/flows and the stores/components and its relationships and links with other systems. They have boundaries and a structure, and show a degree of integration (the components work together).

Question 2

Deserts as natural systems:

The concept of a system

Answer 2

Open system:

Where both matter and energy can be transferred across the boundary into another environment/system.

Question 3

Deserts as natural systems:

The concept of a system

Answer 3

Closed system: Energy can be transferred from these across boundaries (but not matter).

Question 4

Deserts as natural systems:

The concept of a system

Answer 4

The components of a system (general):

1. Elements: parts that make up the system (animals, atoms, sand, etc)
2. Attributes: characteristics that can be measured (size, colour, quantity)
3. Relationships: descriptions of how the elements and their attributes work together to carry out processes (photosynthesis)

Question 5

Deserts as natural systems:

The concept of a system

Answer 5

Components of a DESERT system:

1. Inputs: precipitation, solar radiation, descending air from the ITCZ, wind energy, water energy, insolation, climate change, weathering, sediment (carried in by water or wind).
2. Processes (flows/transfers): Mass movement, wind/abrasion, water erosion, wind-blown sand, surface run-off, salinisation, sediment transfer (transportation or deposition).
3. Stores: Landforms (of deposition and erosion) are stores of sediment, water may be stored in the ground or in rivers and other bodies of water.
4. Transportation processes (like water/wind movement) lead to:
5. Outputs: water loss from run-off or evaporation, and sediment loss from wind or water carrying it away.

Question 6

Deserts as natural systems:

Positive feedback loops in deserts:

Answer 6

Positive feedback loops in deserts:
The presence of absence of vegetation can affect the regional climate. If vegetation is removed, this will reduce the moisture emitted into the atmosphere. This reduced humidity may lead to less rainfall, further reducing the extent vegetation can grow.

Question 7

Deserts as natural systems:

Negative feedback loops in deserts:

Answer 7

Negative feedback loop:
Intense weathering of a slope leads to a large build-up of an apron of scree against the mountainside. Without its removal (by erosion), this apron extends down the mountainside, protecting the lower slopes from weathering.

Question 8

Deserts as natural systems:

Dynamic equilibrium in deserts:

Answer 8

Dynamic equilibrium:
This is a system that has a lack of change, as its inputs and outputs remain in balance. If change occurs, its feedbacks will correct it.

(NB: Negative feedback loops promotes this, and positive loops do the opposite).

Question 9

Deserts as natural systems:

The concept of a system

Answer 9

Deserts are open systems, and are generally in dynamic equilibrium. If a change occurs (from a positive feedback loop), a negative loop can restore the balance.

Question 10

Deserts as natural systems:

What is a desert?:

Answer 10

A hot desert is barren, dry, arid and has little vegetation cover and very high temperatures. They receive small amounts of precipitation (less than 250mm of water as rainfall a year), which defines the place as arid.

Question 11

Deserts as natural systems:

Characteristics of climate:

Answer 11

General aridity rule:
50-100mm of rain = hyper-arid
100-250mm of rain = arid
250-500mm of rain = semi-arid.

Question 12

Deserts as natural systems:

Characteristics of climate:

Answer 12

The Aridity Index:
P = mean annual precipitation
PET = potential evapotranspiration

If P is higher than PET, then there is a water surplus
If P is lower than PET, there is a water deficit

In deserts, P is lower than PET (water deficit).
The index measures the value/extent of this deficit:
Less than 0.2 is a desert
0.2-0.5 = semi-arid
0.03-0.2 = arid
less than 0.03 = hyper-arid

Question 13

Deserts as natural systems:

Characteristics of climate:

Answer 13

The water balance:
The balance between the inputs (precipitation) and outputs (run-off, evaporation, groundwater storage).

This is calculated by: Precipitation (P) = run-off (Q) + evaporation (E) +/- groundwater storage (S).

This shows the relationship between precipitation, soil moisture storage, evapotranspiration and runoff. In deserts, due to the high PET, there is a strain on the lack of water for plant growth. When PET exceeds precipitation, there is a water deficit. This means no water runoff for usage in agriculture, homes, etc. This means that water must be taken from elsewhere or extracted from aquifers, which is unsustainable and costly.

Question 14

Deserts as natural systems:

Characteristics of climate:

Answer 14

Characteristics of desert climates:

1. High aridity and high temp, low precipitation, high solar radiation and high PET
2. High diurnal range (0 degrees at night vs 55 degrees in the day) due to lack of clouds.
3. High atmospheric pressure, no clouds and strong surface winds.
4. Low net primary production and low levels of organic matter
5. The precipitation can be unreliable and go to the extremes, causing low infiltration and high PET. Also, strong winds, sandstorms, even thunderstorms due to extreme temp variations.
6. Rapid surface run-off when intense rainfall hits dry land and doesn’t soak into the ground, it runs off and causes flash floods.

Question 15

Deserts as natural systems:

Distribution of deserts (mid and low latitude):

Answer 15

They are located:
1. Close to the Tropics of Capricorn and Cancer
2. In the interiors of continents (Sahara and Australia),
3. Adjacent to mountain ranges (Andes).
4. Located on the western side of the continents (because of the trade winds and ocean current patterns). (The trade winds move west and by the time they reach the western edge of continents, they have no moisture left and create a desert).
They cover 25-30% of the Earth.

The main hot deserts in the world are:
The Sahara, the Gobi, the Atacama, the Great Victoria, the Sonoran, the Mojave, the Great Basin, the Kalahari, the Arabian and the Thar.

Question 16

Deserts as natural systems:

Characteristics of soil:

Answer 16

Deserts are too dry to support many vegetation, so soils are poor quality and unproductive.
They are high in alkaline, are thin and lack water.
They are dry and sandy (and sometimes red, due to oxidation processes).
The existing moisture can be drawn up to the surface, decreasing the soils mineral content.
The rocks in the soils are iron-rich, highly porous and permeable with poor moisture retention levels.
But, as there is no rainfall, there is no removal of soil nutrients by water and so agriculture can still sometimes be possible (like in the Sahel region).

Question 17

Deserts as natural systems:

Characteristics of vegetation:

Answer 17

It has the lowest productivity value of any biome
Most deserts have vegetation (but it is sparse and scattered), only the sand and very driest areas have none.
Adaptations for vegetation in deserts: they prevent water loss, store moisture in stems/leaves, have deep and wide roots, and short life cycles. They also are resistant to and avoid drought, they store water well and long term, and are tolerant to high salt contents.

Question 18

Deserts as natural systems:

Characteristics of vegetation:

Answer 18

Halophytes: (Salt tolerant plants)
These are adapted to the saline conditions of the soil. Some store salt in glands and then secrete it out on their leaves (e.g., pickle-weed). They have swollen leaves to do this best.

Question 19

Deserts as natural systems:

Characteristics of vegetation:

Answer 19

Xerophytes: (drought resistant plants)
They have thin, tough and spiky leaves with waxy cuticles and tough bark to reduce water loss by transpiration. They are covered in silvery hairs to cut the wind speed and reduce water loss and reflect light, keeping the plant cooler (e.g., Cacti). They also store water in their interior, roots and stems. Their spikes increase their surface areas.

Question 20

Deserts as natural systems:

Characteristics of vegetation:

Answer 20

Phreatophytes: (water seeking plants)
They have long roots that are sent out to tap water under the ground or to control the water supply of a wide area. (E.g., Mesquite). They have thick protective bark and fleshy stems and bulbous roots.

Question 21

Deserts as natural systems:

Characteristics of vegetation:

Answer 21

Ephemerals: (drought avoiding plants)
These produce seeds that lie dormant for long periods between rainfall. They germinate and flower quickly when rain does arrive. They have a short lifecycle (e.g. Cinch weed).

Question 22

Deserts as natural systems:

Causes of aridity (global atmospheric circulation)

Answer 22

Global atmospheric circulation and the creation of the Hadley Cell (sub tropical high pressure).

1. The rising air in the intertropical convergence zone (ITCZ) diverges and spreads both north and south to two distant tropical circulation cells - the Hadley Cells
2. This air moves towards the poles, and converges with the air from the Ferrell Cells in the North/South, causing it to sink.
3. As it sinks, it becomes warmer and drier and establishes a zone of high pressure at around 30 degrees north/south of the equator.
4. This region becomes extremely dry with little rainfall and no clouds (allowing more solar radiation), meaning extreme temperatures and evaporation rates occur.
5. These regions become arid deserts (and this effects all the deserts on earth to varying extents).

Question 23

Deserts as natural systems:

Causes of aridity (Continentality)

Answer 23

Continentality:
1. Large land masses affect the weather and climate. Aridity tends to be higher in continental interiors (Sahara, Australia). This is because the influence of moist airstreams from oceans is reduced.
2. As all the moisture is lost before this air reaches the innermost parts of the continents.
3. There is less influence of the sub-tropical high pressure area.
4. Deserts caused by this tend to be more semi-arid
EX: The Sahara, and the Great Victoria.

Question 24

Deserts as natural systems:

Causes of aridity (cold ocean currents):

Answer 24

Cold Ocean Currents:
1. Deserts are on the coastlines, adjacent to cold ocean currents.
2. The air that is in contact with these cold ocean currents is cooled.
3. This cold air is denser, and sinks to remain close to the ground.
4. Aridity is increased as rain formation is suppressed by the air sinking.
5. This forms a thick layer of fog near the ground, which produces low levels of precipitation
EX: The Atacama or Kalahari Deserts.

Question 25

Deserts as natural systems:

Causes of aridity (relief/rain shadow effect)

Answer 25

Relief/rain shadow effect:
1. As the prevailing winds pass over the moist oceans, they become cold and wet.
2. When these come onto land and hit the mountain ranges, they are forced upwards.
3. As this air rises, it cools and condenses to form clouds, which then rain onto the windward slide of the mountains (the one closer to the coast).
4. So, when the air gets over the summit to the leeward side, it is less moist and becomes warmer and drier.
5. This area becomes a rain shadow and gets no moisture from the air.
EX: The Atacama from the Andes and the Gobi from the Himalayas.

Question 26

Systems and Processes

Sources of energy:

Answer 26

Insolation:
The amount of heat (shortwave radiation) that reaches the Earth’s surface.
The lack of clouds means it is at high levels in deserts.
There is also more at the equator and the tropics, as the rays have to travel a shorter distance.
This determines the extent of weathering (more rays = more weathering)
It increases levels of POTET and therefore the water balance
It can also affect wind systems and aeolian processes

Question 27

Systems and Processes

Sources of energy:

Answer 27

Winds:
Wind is driven by the atmospheric circulation system and is a secondary source of energy in deserts.
The wind can mould and transport sediment through erosion, this creates aeolian landforms.

Question 28

Systems and Processes

Sources of energy:

Answer 28

Water (run-off):
Fluvial processes are rare, but powerful, following an infrequent heavy storm, water will flow in dry rallies or gullies (Wadis).
The water will erode this rock and make a gap.
Some exogenous rivers also affect the deserts, and get water from wetter climates and bring it to the area, making fluvial landforms (like the Nile).
Meltwater can also come from mountains or glaciers and affect the desert (like the Atlas Mountains and the Sahara/the Himalayas and the Gobi).

Both water and wind are ‘agents of erosion and transportation’ in deserts.

Question 29

Systems and Processes

Sources of sediment:

Answer 29

Sediment Sources:

1. Weathering of underlying rocks (mass movement, rock falls, soil creeps) or weathering of exposed rocks (exfoliation, chemical weathering) or erosion or rock on a desert plain (desert pavements).
2. Fluvial sources (rivers bringing sediment in or floodwaters depositing sediment on banks, sediment washed onto desert plains by wadis or meltwater carrying sediment down from mountains).
3. Aeolian sources (wind blowing sediment into deserts and depositing it there).

Sediment is also lost through these ways too.

Question 30

Systems and Processes

Sediment Cells:

Answer 30

Sediment Cells is the movement of sediment by wind and water.
These cells have inputs, outputs, transfers and sediment sinks (areas of deposition)

Question 31

Systems and Processes

Types of sediment inputs:

Answer 31

Endogenous: from inside
Exogenous: from outside
(Wind is an exogenous force, water can be both).

Question 32

Systems and Processes

Sediment Budget:

Answer 32

Deserts have sediment budgets

1. Net gain: If the inputs > outputs, then the system has a net gain and a surplus of sediment
2. Net loss: if the outputs > inputs, then the system has a net loss and a defect of sediment.

Question 33

Systems and Processes

Processes of weathering:

Answer 33

Weathering is the breakdown or disintegration of rocks in their original place.

Mechanical: This is weathering without chemical intervention.

1. Thermal fracture: intense temp fluctuations cause rocks to expand when heated and contract when cooled (high diurnal range). This fractures the rock and breaks it down (moisture helps this process). It is dependent on the colour, lithology and structure of the rock.
2. Granular disintegration: happens to granular rocks (granite/sandstone), where they are thermally fractured and crumble into grains of sand.
3. Block separation: happens to rocks with clear joints (limestone), blocks will break off.
4. Shattering: happens to rocks without clear joints or grains, they shatter and form angular fragments (basalt).
5. Exfoliation: happens as rocks are bad conductors of heat, and so their outer surfaces are prone to heating and cooling and expansion. This leads to their outer skin peeling away (exposed sandstone/granite).
6. Differential expansion: is the difference in expansion of rocks with clear joints breaking into blocks/angular fragments vs grainy rocks forming grains of sand.

Question 34

Systems and Processes

Processes of weathering:

Answer 34

Chemical weathering (usually with water involved)

1. Salt crystallisation: when it rains, the water dissolves salts in the soils. The high levels of POTET draws water to the surface and salt crystals form and are deposited on the surface, growing and expanding to crack the rocks over time.
2. Hydration: when water gets into the rocks, it interacts with the chemicals in them, forcing water and sodium to react and form salt. This reforms the rocks’ chemical structures and the salt can crystallise and break down the rock.
3. Hydrolysis (solution): the breakdown o rock by acidic water to produce change in the chemical makeup of the rock, breaking it down slowly.
4. Oxidation: the breaking down of rocks by oxygen and iron reacting to form iron oxide, which weathers the rocks and gives it a rust. This changes the chemical composition (the rock is more fragile and can crumble with erosion).

Question 35

Systems and Processes

Processes of weathering:

Answer 35

The importance of water and impact on rates:
The water content, temp levels and chemical density/makeup of the rocks affect the rates of weathering.
The intensity of fluvial processes and higher temps will increase the rates of weathering.
If the chemical make-up of the rock is ideal for chemical reactions (lots of sodium or iron) then it will increase rates.

Question 36

Systems and Processes

Mass Movement:

Answer 36

Mass movement: is a large scale movement of the lithosphere down a slope under the influence of gravity, which are normally caused due to water weathering.

1. Rock fall: rocks fall off cliff sides (usually due to freeze thaw weathering).
2. Landslides: the breaking off of unsaturated or saturated soils and weak rocks along a sloped hill.
3. Mud or debris flows: the movement of the loose materials that become so saturated, they act like liquids. This can be a slow move (creep) or rapid.
4. Slumps and land slides: material blocks of rocks slide downhill along a sloped hill, forming steps.

Question 37

Systems and Processes

Mass Movement:

Answer 37

Mass Movement in deserts:
Due to the extreme changes in weather, the thin and dry desert soils suddenly can be hit by a lot of water (storms, rainfall or flash floods), resulting in the mass movement and flows.
The dry soils will liquify and the rocks and vegetation will fall.
(The lack of vegetation means less shear strength/resistance and the slopes becoming unstable).
If the desert is affected by cold ocean currents, there will be moist air and mist at low levels, making the slopes softer and more unstable.
The most common mass movements are rockfalls and some landslides/slumps.

Question 38

Systems and Processes

Mass Movement:

Answer 38

Factors that increase risk:
1. Slope stability: when gravitational force > resisting force on a slope, failure occurs
When the shear stress > shear strength = slope failure (MM)
2. Water: some water increases shear strength as it increases surface tension, but too much will act as lubricant and increase shear stress.
3. Gravity: the steeper the slope, the more shear stress.
4. Earth materials: loose soils or rocks, vegetation, thin soils, old landslide sites pose greater risks of MM
5. Triggering events: heavy rain, storms, fires or earthquakes can trigger MM.

Question 39

Systems and Processes

Erosion:

Answer 39

Types of erosion:

1. Splash erosion: the force of falling rainwater displacing soil particles
2. Sheet erosion: water running as a sheet over impermeable surfaces or compacted soils washing away disturbed particles.
3. Rill erosion: Sheet wash wears down the soil to form a definite path in the soil (rills), where water can flow through.
4. Gully erosion: over time, rills become wider and deeper to form gullies.
5. Bank erosion: Fast water flows wear away the stream sides, causing banks to collapse and the channel to widen.

Question 40

Systems and Processes

Aeolian processes of erosion:

Answer 40

Wind is common in arid areas because: air that is near the ground heats up and rises, resulting in cooler air rushing in to replace it, creating wind. This happens constantly and is then helped as the landscape is so barren and nothing blocks it.

1. Deflation: This is the removal of loose material from the desert floor, exposing the rock underneath. Over time, this surface is lowered and only the strongest rocks remain. Moisture can increase the rate of this by breaking up the rocks. Strong localised winds can create deflation hollows (a with in the floor).
2. Abrasion: Winds blow sand that hit against rock surfaces, carving or sculpting them into shapes. Much of this happened within a metre off the floor. This concentration can result in mushroom shaped rocks.

Factors that increase abrasion rates are: the intensity of and duration and direction of the winds, the nature of the wind-blown sand (rock type and angularity) and the lithology of the target rocks (vulnerability).

Question 41

Systems and Processes

Aeolian processes of transportation:

Answer 41

1. Suspension: fine sands may be picked up and carried by winds, sometimes miles. This is very common when high velocity winds create sandstorms.
2. Saltation: sand particles move in a series of leaps as they are picked up by a gust of wind before being dropped again a few centimetres forward.
3. Surface Creep: larger sand particles are rolled along the floor.
4. Deposition: this occurs when the wind velocity falls below a critical value, where the sand cannot be carried or moved anymore. This velocity varies according to the size of the particles.
   Normally, deposition will occur in sheltered areas from the wind.

Question 42

Systems and Processes

Fluvial processes - sources of water:

Answer 42

Sources of water:
1. Exogenous: rivers that have their source outside the desert system (usually mountains) and flow into an ocean at the end have enough water supply to flow continuously despite the high rates of POTET.
EX: the Nile or the Colorado rivers.
2. Endoreic: rivers that flow into deserts but terminate in a lake or inland sea, rather than an ocean.
EX: The river Jordan, which drains into the Dead Sea.
3. Ephemeral: rivers that flow intermittently in deserts, maybe after storms. They can be fed by snowmelt from mountains. Flow rates can vary a lot, and can be powerful forces of erosion in times of flooding.

Question 43

Systems and Processes

Fluvial processes - the episodic role of water:

Answer 43

Sheet floods and flash floods:
These are infrequent but very powerful rainfall events that tend to involve torrential/convectional storms with a lot of water in a short time period.
The dry soils won’t absorb the water, resulting in a lot of overland flow and erosion.
Water flows as a sheet across the land (sheet flows), or is confined within a channel (flash floods). During these events, large amounts of sediment is washed away from the mountains (sources) and is deposited as alluvial plains in the desert below.

Question 44

Arid landscape development

Ventifacts:

Answer 44

Ventifacts (aeolian landform):
These are small-scale features found on desert pavements.
They are individual rocks, usually the size of pebbles that have a clearly eroded face that is aligned with the prevailing winds.
Some have such a clearly eroded face, that it is clear which direction the winds are moving (Dreikanters).

Question 45

Desertification:

What is it?

Answer 45

Definition:
The destruction of the biological potential of the land (ecosystems and habitats), which leads ultimately to desert-like conditions. Land that was once marginal becomes engulfed in the desert system as unproductive wasteland, vegetation dies and soils become dry and eroded.

Question 46

Desertification:

Distributions of hot deserts over time:

Answer 46

How has the extent of deserts changed in the last 10,000 years?
1. 20,000 years ago there was a glacial period. Carbon dating and pollen analysis has allowed scientists to investigate patters of the world’s vegetation zones from millennia ago, showing where the deserts were.
(The Sahara and Gobi were larger, the cold deserts of Canada, Siberia and Argentina were also larger).
2. In the interglacial period 8,000 years ago, the climate has been quite stable. The atmospheric circulation system has not changed and the conditions overall have been much warmer, increasing vegetation and humidity (creating more tropical conditions).
(There were tropical conditions in Russia, Canada, SA, SE Asia/China, Congo region, even Australia, with the only remaining deserts being the Gobi, Atacama and Sahara).
3. 5,000 years ago, the climate became less humid and tropical and aridity increased. This meant only the very driest areas have remained desert.

Question 47

Desertification:

Distributions of at-risk areas:

Answer 47

The areas at the most risk are the areas on the margins of deserts (marginal land).
1/3 of the Earth’s surface is at risk. For example, the Sahel, Iran, west USA, Australia, Central Asia.

Question 48

Desertification:

Causes of desertification: Climate Change

Answer 48

1. Climate change: this leads to less rainfall (amounts and reliability), increased drought (frequency and intensity).
2. Also leads to global warming - higher temps, increased evaporation, reduced condensation.
3. This leads to rivers and water holes drying up and less rainfall.
4. Vegetation dies and there is a decrease in protective vegetation cover.
5. This leads to desertification

Question 49

Desertification:

Causes of desertification: Increase in animals

Answer 49

1. increase in animals or farming exceeding the carrying capacity of the land (in some areas there has been a 40% increase since the 1960s).
2. This leads to overgrazing or over-cultivation - soil is depleted of nutrients, land is stripped of its protective grass cover
3. This means vegetation cannot re-establish itself and the soil is exposed to wind and rain.
4. This leads to desertification.

Question 50

Desertification:

Causes of desertification: population growth

Answer 50

1. Population growth can be from increasing birth rates or immigrant/refugee rates.
2. Farmers are forced to change traditional methods of land use to make more food and cash crops.
3. This is over-cultivation, reducing soil fertility and leaving the soil exposed.
4. There is also an increased demand for wood (for cooking, heating, building).
5. This leads to deforestation.
6. Both of these ways leads to vegetation being removed and the ground damaged.
7. There is an increase in evaporation from soils and more risk of soil erosion.
8. This leads to desertification.

Question 51

Desertification:

Causes of desertification: Tourism

Answer 51

1. Tourism leads to trampling of vegetation and soils (by foot or cars), over irrigation of soils (due to increased food demand) and more demand for wood.
2. Over-irrigation leads to salinisation of soils, making them infertile
3. More demand for wood leads to deforestation
4. This all leads to a lack of vegetation and more soil erosion
5. Eventually desertification will occur.

Question 52

Desertification:
Case Study: The Sahel (Senegal)
Causes:

Answer 52

Causes:
Climate change, over-grazing, over-cultivation, population growth, tourism.
The livestock sector is 7.5% of the GDP
2/3 of families in rural Senegal are dependent on Peanut cultivation for income (cash crop).
This leads to overgrazing and over cultivation/exploitation of the land.
66% of the rural families live in poverty and can’t afford good irrigation systems and so can’t sustainably use the land.
The introduction of western chemical fertilisers has eroded the top-soils are made them unusable, whilst also polluting them and the ecosystems around them.
The lack of rainfall increases this process as it keeps the area dry.

Question 53

Desertification:
Case Study: The Sahel (Senegal)
Impacts on ecosystems

Answer 53

1. Ecosystems: are affected by the loss of nutrients due to overexploitation,
   There is topsoil erosion due to more exposure to wind and rain.
   More salinity due to over-irrigation and overexploitation of fertilisers.
   Water sources become depleted and the water table falls (plants and animals die), and this causes animals to migrate and destroy other lands.

Question 54

Desertification:
Case Study: The Sahel (Senegal)
Impacts on people

Answer 54

2. People: the lack of water results in them drinking dirty water and spreading diseases.
   The loss of vegetation reduces food productivity , forcing abandonment of settlements and overcrowding of cities.
   The exposed soils are more likely to cause sandstorms and dust clouds, affecting air quality and causing respiratory problems and visual impairment (Dakar 2018).
   Food insecurity causes famine and malnutrition, depleted soils create a lack of productive land or livestock space (adaptation to this is hard and rare, most people leave to cities).
   People also start to deforest more to get fuelwood for heat/wood to resettle elsewhere, this causes a positive feedback loop.

Question 55

Desertification:
Case Study: The Sahel (Senegal)
Impacts on the landscape

Answer 55

3. Landscapes: Sand dunes will form as loose material is no longer trapped by vegetation.
   Soil erosion by water can cause deep gullies to form (Wadis).
   Landslides can occur on steep hills when vegetation is removed.
   Sandstorms become more common when the protective layer of vegetation is removed, leading to more abrasion.

Question 56

Desertification:
Case Study: The Sahel (Senegal)
Solutions

Answer 56

1. The company ‘Bonergie Irrigation’ are creating new sustainable irrigation systems for large scale farming in Senegal.
   They have committed $320,000 to improving the sustainability of irrigation systems.
   They have given smaller scale farms solar panels, to allow for ethical irrigation.
   This will allow them to farm the land more sustainably, and not increase desertification by degrading the soils.
2. The Senegalese government are also encouraging the population to use their animal manure to fertilise the soils sustainably, giving back the moisture taken from the soils through their crops (this is called Zero-farming).
3. Senegal is one of the nations involved in the ‘African Great Green Wall’ project, where the people on the Sahel have planned on planting a wall of trees across the 8,000km width of the continent. This will improve the soil quality and push back the negative effects desertification.
   This helps many countries and is also a way to reduce climate change.

Question 57

Desertification:
Case Study: The Sahel (Senegal)
Implications for development

Answer 57

Many people already live in poverty in Senegal.

1. The rural communities are trying to use their lands to get crops and raise animals to eat and make slim profits at markets. They will suffer the most when it is not their fault.
2. The people in cities will be affected by less clean water, more sandstorms, and more dry land around the city.

These issues are detrimental to Senegal’s capacity for development, as it stops farming and removes natural resources.
It can’t be solved by international aid and is almost impossible to reverse. As Senegal becomes mostly desert, it will add to the poverty and impact on people hugely (not much development will be realistic).

Question 58

Desertification:
Case Study: The Sahel (Senegal)
Evaluation of solutions

Answer 58

Overall, the solutions that Senegal have proposed are good, especially the Great Green Wall. It is good that the government is taking notice of this.
However, the government must intervene more and cannot rely on organisations and NGOs to help them solve the issue.
These projects are too large scale too, and unrealistic to achieve in the near future. More small scale, bottom up projects, supported by gov funding must be introduced ASAP.