rural land degredation Flashcards
(33 cards)
What is rural land degradation
Rural land degradation basically means soil deterioration.
Soil is said to be deteriorated if it cannot support the vegetation cover it previously supported.
Degradation occurs when the soil is exposed and is worn away by weathering.
If this happens faster than the soil is being formed, then the soil will begin to degrade.
Rain erosion processes
Rain splash The impact of raindrops on the soil can dislodge and move soil either outwards (flat land) or downhill (on a slope).
Sheet Erosion The removal of the surface topsoilby heavy rain gently flowing down a slope.
Rill Erosion The creation, by heavy rain, of small (usually temporary)water channels. Over time these can lead to larger gullies.
Leaching - When heavy rain washes out minerals from the topsoil.
wind erosion processes
Suspension Very fine material (<0.15mm) is picked up and carried large distances by strong winds.This can cause a dramatic looking dust storm. Fine and coarse grained sand particles are lifted first vertically, then they are bounced in a “leap-frogging” motion over each other, but close to the ground.
Surface Creep A very slow movement over ground,usually large particles of soil or stones (dislodged due to moving sand grains ^), rolling and sliding
Physical Causes of RLD in the Sahel
- Variability and intensity of rainfall: Total annual rainfall is low in the Sahel, ranging from 200mm in the N. Sahel, to 500mm in the S. Sahel (there are distinct wet & dry seasons). The hot temperature also means there is a consistent high rate of evaporation which leaves the soil dry and open to wind erosion.
drought periods are occurring in the Sahel with greater frequency than previous years.
DROUGHT = Water table falls & soil dried out = plant roots can no longer access water plants die lack of soil veg. leaves soil exposed to wind and rain erosion RLD!!
The variability in rainfall can also cause a human problem: many “wetter” years in a row can give locals false hope about the land’s capability. They often then plant more crops following some success, but when the climate dries again the crops fail again, causing more damage. - Vegetation Cover Due to the variability of rainfall across the Sahel, the soils and natural vegetation also vary. In southern regions where rainfall is more reliable, soils are well developed, fertile and support a greater variety of vegetation.
Moving North, vegetation becomes less dense leaving the soils bare and therefore more susceptible to erosion by wind and water
Human causes of rld in the Sahel
Over population Over cultivation Over grazing growth of cash crops Poor irrigation methods Deforestation Urbanisation
Over population
improvements in medical care resulting in reduced death rates, coupled with high birth rates, mean that population growth is occurring rapidly in the Sahel.
With more mouths to feed, greater pressure is placed on farmers to produce more food leading to over-cultivation.
Over cultivation
Due to increases in population arable farmers are forced to increase yields from their land. As a result, the fallow periods (when land is left un-seeded) allowed for the soil to regenerate is reduced and the soil becomes depleted of its nutrients.
With rainfall in the region increasingly unreliable, crops often fail and the soil is degraded (exposed to wind and rain!).
Over grazing
the rise in population has brought about an increase in the size and number of herds grazing in the Sahel, increasing pressure on grazing areas (e.g. wells and lakes where animals drink).
The sheer volume of grazers results in vegetation being stripped down to the roots, leaving soil exposed to wind and rain.In addition, compaction of the soil by trampling reduces the infiltration capacity increasing runoff resulting in erosion of the soil by water.
growth of cash crops
many farmers moved away from the traditional subsistence farming (growing enough for themselves) and began growing cash crops (crops to sell) such as cotton and rice.
This resulted in monoculture.
Monoculture is the cultivation of the same crop on the same fields year after year which depletes the soil of vital nutrients. As a result the soil structure is weakened, crop yields are reduced and the soil is degraded.
Poor irrigation methods
In a dry climate, crops must be irrigated. In Niger water was pumped out of the River Niger to irrigate fields of rice.
The pumped water floods the rice paddies but the excess water then evaporates in the heat of the day leaving behind large concentrations of salt in the soil which poisons crops
Deforestation
Rising populations place an ever increasing burden on woodland which is the main source of fuel in the Sahel. Removing the trees removes the binding effect tree roots have on the soil, the protection of soil by vegetation and the ability of the trees to reduce wind speeds; therefore without the trees the soil is left exposed and liable to be eroded.
In addition, the shortage of firewood for fuel means that more families are resorting to animal dung for their domestic energy. The dung would normally be used as a natural fertiliser for the soil.
As a result, the soil is further degraded as it is deprived of the nutrients. In the long term crop yields will be affected.
Urbanisation
In many parts of the Sahel there has been a rapid growth in urban populations as people move from rural areas in search of jobs, a higher standard of living and better education opportunities.
Urbanisation has led to an increased demand for firewood. -
Large areas of forest are cut down and the wood is often turned into charcoal for ease of transport. This process is extremely inefficient and half of the energy of the wood is lost during conversion. The growth and development of small settlements in rural areas has also increased, as schools have been set up, as in Korr in Northern Kenya.
CONSEQUENCES of RLD in the Sahel
Environmental consequences (physical changes to landscape) Economic Consequences (financial implications for countries involved) Social Consequences (changes for the people involved)
Environmental Consequences
Rills and gullies
Loss of topsoil
Environmental Consequences
Rills and gullies
exposed soil and intense tropical downpours results in overland flow removing topsoil and cutting into the land, forming rills and gullies.
This is also a problem where soil has been compacted by the trampling of animals.
Loss of topsoil
strong winds blow away the topsoil from land that has become degraded.
Topsoil is the most fertile part of any soil.Losing this means crops are unlikely to grow well leading to further low crop yields and crop failure.
Environmental Consequences
cash crops often require more water to grow which has led to an increase in flood irrigation, causing salts to accumulate in the soil.
If these soils are not drained properly, salts will build up in the root zones of crops. This can kill the crops and contaminate the soil.
To reverse the process and rejuvenate the soil is very expensive
Economic Consequences
Reduced income from pastoral farming and the farming of cash crops
Increased rural poverty as farming is a traditional way of life in the Sahel
A decrease in the available fuel (normally wood), resulting in people buying alternative fuels (e.g. oil and kerosene which is more expensive!).
In areas where the effects of RLD have been most serious, people have come to rely on food and other aid sent from other countries (e.g., following the Band Aid campaign of 1983). This can lead to an over dependency on external help and can even have a negative impact on people’s psychological health who cannot provide for themselves/need aid.
Social Consequence
Malnutrition and starvation
Migration
Health and education
Malnutrition and starvation
the failure of crops year after year leads to starvation and death e.g. one million people died in the famine in Ethiopia in the mid-1980s.
Malnutrition may also be attributed to the reduction in the range of crops grown in order to concentrate on cash crops.
Migration
the degradation of farmland and the increased pressures created by rising populations have forced people to migrate away from their home areas in the Sahel.
Additionally, the younger men move away in search of an alternative income, leaving the women, children and the elderly at home.
This has led to a demographically imbalanced rural population.
Health and education
in many Saheian countries (countries within the Sahel) such as Burkina Faso, education and health care must be paid for and therefore the loss of income brought about by the failure of crops and herds may mean that individuals have their schooling interrupted leading to low literacy rates, and individuals go untreated when ill leading to higher death rates.
Extra social consequences
Governments and charities may have to set up refugee campsdue to mass migration away from the Sahel.
The conditions in the camps are likely to be appalling (overcrowded, insufficient health / education facilities).
Increased social tensions(people are unhealthy, hungry and unhappy)
A loss of traditional knowledge and skills in the area
People will die, communities become broken up and a way of life is lost.
Model answer - consequences of rural land degradation on environment and people 10m
The Semi-Arid area I have studied is the Sahel in Africa where there are many consequences of RLD.
The variable rainfall pattern within the Sahel, which often results in torrential downpours during the wet season, causes increased overland flow.
This results in the nutrient rich topsoils being washed away, aiding desertification. (1)
This process has led to the Sahara expanding by 100km in just 17 years in Sudan (1).
Over cropping and overgrazing leave the soil bare and exposed to wind and water erosion. Torrential rain in the Sahel can then lead to the formation of Rills & Gullies (deep ridges in the soil). These rills and gullies cannot be ploughed out and so are permanent features. This leads to less land being available for arable farming which is the main way of life in the Sahel (1)
The lack of good quality soil has led to lower crop yields and increased crop failures. In the worst affected areas, such as in Ethiopia, this has led to starvation and famines(1)
(one million people died in the Ethiopian famine in the mid 1980’s). (1)
A poor quality of life, caused by poor quality soils and the resulting starvation, has forced many Saheians who lead traditional agricultural lifestyles to migrate to neighbouring countries in search of other employment, food and shelter. This has caused a rise in the number of Shanty Towns (1).
Some people are also forced to flee their homes in the Sahel as they are unable to access food and water. These people become refugees and move to neighbouring countries. In some cases, this can cause conflicts with the resident populations (1).
In some cases, it is solely the young men in families who migrate to new shanty towns or cities to find work. This leaves behind the women, children and elderly, causing a massive demographic imbalance in affected rural Saheian countries (1).
Starvation and lack of resources in the Sahel caused by poor quality soils and poor crop yields can also mean that certain populations become susceptible to diseases like Kwashiorkor disease (1).
Kwashiorkor disease causes swelling of the gut due to malnutrition) means many people are then unable to work, so cannot afford food (1).
In many Saheian countries such as Burkina Faso, education must be paid for, and therefore the loss of earnings brought about by crop failures (or the effects of this, e.g. disease) may mean that individuals have their schooling interrupted leading to low literacy rates (1),
e.g. in Niger the literacy rate is only 19% (1).
Healthcare must also be paid for in most parts of the Sahel, again meaning that those who cannot afford it due to crop failures caused by rural land degradation go untreated when ill, resulting in a higher death rate(1)
