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Land (soil) degradation refers to the deterioration of the quality of land (soil) through the loss of fertility, soil pollution, erosion and mass wasting. Degradation rendered soil useless for human developmental activities and unfit for the life of soil biota.
Loss of soil fertility;
This refers to the decline in the soil ability to support plant growth through the failure to provide necessary nutrients for plant growth. Loss of fertility can brought about in a number of ways as explained below:
1) Leaching process: This washes down the necessary nutrients in solution from the topsoil. It makes soil become more acidic and hence toxic. It is common in areas, which are humid and experience heavy rains.
2) Over cultivation: In certain areas caused by the rapid population growth. The crops grown on the same piece of land for a long time lead to depletion of soil nutrients.
3) Monoculture that involved cultivation of one type of crop without crop rotation or inter cropping. Nutrients are used up without replacement and the soil structure can be destroyed rendering the soil unstable.
4) Soil pollution due to excessive use of chemical like pesticides and artificial fertilizers, dumping of harmful wastes in the soil, and acidic rain that make the soil toxic, structure less and hence unproductive.
5) Soil erosion accelerated by poor land management like deforestation, flat cultivation on the slopes, etc.
6) Mass wasting that leads to the loss of the upper layer of soil and its nutrients.
7) Severe loss of soil water through excessive vapor- transpiration especially in arid and semi arid areas.
Soil erosion refers to the wearing away, detachment and removal of soil material from one place to another through the agents like water, wind, ice and gravity.
Types of soil erosion:
Two major types of soil erosion can be distinguished and these include normal geological erosion and accelerated erosion. Is the wide spread type of erosion that occurs wherever there is natural flow of energy and matter on the earth’s surface without human (anthropogenic) influence. It is fortunately very slow and so not normally injurious to the soil cover of the world. More often than not, its rate is either slower or equal to the rate of soil formation hence its effects are rarely noticeable. Erosion under this category is easy to control.

Accelerated erosion;
Is the type of erosion associated with man’s activities (man induced or anthropogenic). It is spectacular in nature (very destructive), therefore it has attracted man’s attention. Its side effects include physical loss of soil nutrients, leading to severe economic loss arising from the reduced crop yield or total crop failure, and / or wasted efforts and money spent on unsuccessful soil conservation projects.
Factors Affecting or Controlling Accelerated Erosion;
These factors can accelerate or decelerate the rate of erosion; they induced physical and human factors.
Physical factors range from climate, topography, nature of soil and vegetation cover;
1) Climate: Where there is heavy rainfall erosion takes place easily while where there is little rainfall the rate of erosion is also low.
2) Topography: On steep slopes soil erosion tends to be severe while it is slow on gentle slopes.
3) Nature of soil: Erosion tends to be severe where soil is loose and tends to be slow where soil is stable.
4) Vegetation cover: Where there is dense vegetation soil erosion tends to be slow while where the soil is bare and the ground is sloppy soil erosion tends to be sever.
Human factors include management styles and population change.
  1. Good soil management like crop rotation and a forestation helps in reducing or checking soil erosion but where there is poor soil management erosion takes place easily.
  2. Population increase also leads to over exploitation of resources especially minerals, forest and land through over cultivation. All these lead to soil erosion.
  3. Human activities that cause accelerated erosion include poor cultivation like monoculture and flat cultivation, excessive mining construction activities which involved building of houses, construction of roads etc; excessive cutting down of tees for lumbering and fuel; overgrazing and casual burning.
Effects of Soil Erosion
Soil erosion has various effects which include water pollution, loss of soil fertility, migration of people, reduction size of arable and deforestation, destruction of animals habitat accelerating weathering process by exposing the rocks disrupting transport and communication network, destruction of tourists centers and houses, and making man incur costs of repair after destruction has been exacerbated by self erosion.
Soil management renders to the skillful use or wise utilization and control of quality of soil (land) resource. Soil conserva
tion refers to the process of preserving the soil for proper and sustainable use. Management and conservation of soil involve the following activities, which are carried by human being.
1) Educating people so as to promote land management skills among them. This has to be undertaken by the government in collaboration with NGOs and some individuals.
2) Training and encouraging farmers to use proper farming methods like crop rotation, inter-cropping, and the use of organic manure. Other methods that can be encouraged include strip cropping and contour ploughing.
3) Planting of cover crops, a forestation and reforestation in order to check soil erosion.
4) Reducing or stopping the use of industry chemicals which tend to accumulate in the soil and cause deleterious pollution.
5) Waste products should be recycled rather than dumping in the soil.
6) Animals should be destocked in order to avoid overgrazing that leads to destruction of grass.
7) Encouraging dry farming that involved mulching in order to reduce loss of water through evaporation especially in dry areas.
8) Land lining with brushwood should be used where the oil has been severely eroded producing gullies.
9) Population should be controlled so as to discourage excessive exploitation of resources, which in turn leads to land degradation.
10) Alternative energy resources should be explored and used effectively to avoid the excessive use of forest materials and oil, which causes hazards to the environment.
11) Radioactive materials should be dumped very deeply in the soil to prevent the upper soil layer from being highly affected.
12) Terracing, and construction of stone lines (like in Burkina Faso) and check dams (like in China) should be undertaken so as to control the movement of water and force it to get into the soil rather than flowing over the land.
13) Developing other economic activities rather than depending on agriculture only especially in the developing countries.
14) The government should formulate good policies, which advocate community participation, land tenure and encourage the proper use of land. Where possible people should be given financial support so as to invest unscientific agricultural techniques, which are not precarious to the soil.
Environmental Hazards and Catastrophes, some key terms;
1) Hazards are the event that occurs and when taking place they put the life of living organisms in danger or at risk.
2) Antistrophe refers to a disaster or calamity that entails destruction of properties as well as environmental degradation.

-Catastrophes are caused by hazards and they are assessed in terms of damage or loss which occurs when the destructive events strike at a place.
-Hazardous events include acid rain, drought, floods (e.g. caused by El Nino rains), famine, storms, earthquakes, volcanic eruptions, epidemics, pests, and mass wasting.
Acid Rain;
All natural rain (precipitation) is usually somewhat acidic as a result of solution of gases like carbon dioxide that react with water to form acids. Carbon dioxide forms carbonic acid (H2CO3). Clean rainwater has the PH value between 5.5 to 6) PH 7 is neutral. Highly acidic water has the PH value lower than 5. It can be 2.4 -5. But recent research in some places have shown that some rainwater contain more than average amounts of acids. This was first discovered in Scandinavia in the 1950s. Acid rain, therefore, is the rain containing more acids than normal amount.
Formation of acids rain;
  • It is formed in the air from sulphur dioxide and nitrogen oxide which are emitted by thermal power stations, industry, motor vehicles, strip mining of coal and burning of coal, sea spraying suing chemicals containing sulphate minerals.
  • Developed (industrialized countries) are the major contributors in this problem. These are the USA, Britain, Japan, etc.The countries greatly affected by acid rain include Scandinavia, the UK, Eastern Canada, and Germany in the black forest.
Effects of acid rain;
1) It leads to the increase in acidity in water bodies killing aquatic animals and plants. This is water pollution.
2) It also leads to the increase of acidity in soils reducing the number of plants that can be grown. Some plants die leading to poor agricultural production.
3) It is washed away through the leaching process accelerated by the presence of acids in the soil. In Germany and Eastern Canada forests died because of this phenomenon. The trees die because they become less resistant to drought, frost and diseases. Also their cells are destroyed.
4) As water supplies become acidic they pose a threat to the future health condition. For example the release of extra aluminum has been linked to Alzheimer’s disease.
5) Different structures like buildings, monuments and bridges are destroyed as a result of the corrosive action of acid on paints and rocks containing calcium.

6) Erosion of limestone rock leads to the formation of features like sinkholes, do lines and gripes.
7) Sulphuric acid lead to itching and irritation of eyes in human being and animals.
Measures towards combating the problem of acid rain;
1) Spraying the trees to wash off acids and auditing of line to the soils, lakes and rivers to reduce acidity. These have been done in Germany and Scandinavia. But these processes are expensive and not sustainable since they have to be repeated continually.
2) Reducing the emissions of sulphur dioxide and nitrogen oxide by using non-fossil fuel, coal which contains less sulphur, removing sulphur from coal before being used. This is desulphurization and can be done by either washing finely ground coal or treating sulphur with chemicals.
3) Introducing the new boilers in power stations which can burn sulphur dioxide into ash. This can be done by burning coal and limestone together so that sulphur can stick to limestone when burning. This process is referred to as fluidized bed technology.
4) Trapping sulphur dioxide from waste gases and spraying it with water so that it can form sulphuric acid which can later be neutralized by adding lime. This process of removing sulphur dioxide from waste gases after use is referred to as Fuel Gas Desulphurization.
5) Using alternative sources of energy, which do not pollute the air. The country can turn the coal-fired power stations into gas-fired power station or becoming more reliant on nuclear power. Also geothermal power, solar power, water power as well as wind power can be used since these are environmentally sustainable.
6)Using less energy by turning off the lights when not is use since the cables tend to produce nitrogen oxide when the electric current is passing.
7)Use car pools, public transportation or resort to walking so as to reduce the burning of fuel oil that leads to the production of nitrogen oxide.
8) Recycle the wastes to avoid unnecessary decomposition that leads to the production of sulphur gas.
9) Reduce air conditioning and the use of heat since these produce nitrogen oxide.
10) Replacing the old appliances and electronic gadgets with the newer energy efficient products.
11) Adding scrubbers to utility plants so as to reduce the emission of Nitrogen gas.
12) Strict policies should be formulated to restrict the use of energy that leads to emission of sulphur dioxide or to control human activities so that the rate of production of sulphur dioxide and nitrogen oxide can be reduced.

Drought is a state on an area facing prolonged conditions of dry weather without precipitation or long period of dry weather when there is not enough water. Drought and desertification have something in common in terms of occurrence and effects.
Causes of drought
Natural causes
These entail natural aspects like the wind system dynamics, the shifting of the overhead sun, natural location of some places, Natural fires and earthquakes.
Wind systems that are dry since they have blown across very narrow water mass stretch cause drought, as they have not picked enough moisture to cause rain formation. The Hartman winds of West Africa are such types of winds which have contributed to the occurrence of drought conditions in many West African countries, particularly the Sahara region.
Some of the winds are dry because they have passed across the cold ocean currents over which they have dropped a lot of moisture and hence reach the surface when they are already dry causing dryness. Dryness in the western part of Southern African countries especially in Kalahari is due to cold dry winds that cross the Benguela ocean currents. In areas where there are descending winds, there is no rain formation since the descending air masses are stable and do not causes rain formation. Rain formation happens where air masses rise, cool leading to condensation and later rain formation.
Shifting of the position of the overhead sun
It is the shifting of the overhead sun takes place, the rainfall regime shifts. If it shifts to the Northern Hemisphere, there occurs dryness in the Southern Hemisphere and when it is in the southern hemisphere dryness occurs in northern hemisphere.
tion of places
Some places are located in the leeward side of the mountains and therefore experience dryness due to the rain-shadow effect. Other places are located very far in the interior such that they end up receiving low amount moisture or no moisture at all.
Natural fires
These are the fire caused by the natural hazards like lightning and volcanic eruptions. These can lead to a large scale destruction of vegetation leaving the land bare. The bare land can then experience excessive evaporation that leads to loss of moisture and hence the occurrence of drought.
Man induced causes
These entails activities carried out by man such as:
1) Lumbering that leads to deforestation due to excessive cutting of trees.
2) Bad agricultural practices like overgrazing, over cultivation, and shifting cultivation.
3) Establishment of new settlement areas due to the increase in population leads to cutting of trees.
4) Mining activities and construction of dams can also cause deforestation.
5) Industrial activities and cars have an impact on the occurrence of drought. These emit gases that cause global warming and acid rain. These causes death of vegetation leaving the land bare and later the occurrence of drought.
6) Other factors involve poor or lack of population policies, low level of technology and poverty. These have led to poor environmental management that has resulted in the destruction of vegetation and thus the occurrence of drought.
Impacts of drought;
1) It has led to poor supply of water for domestic use, agricultural use and industrial activities.
2) Drought has caused the disappearance of vegetation in many places especially in the Sahel region in Africa.
3) Poor energy supply among the people who depend on firewood as the main source of energy. This has faced people in West Africa.
4) Lack of moisture in the soil has led to death of plants. The land left bare due to the death of vegetation is susceptible to erosion.
5) Excessive evaporation
has led to the drying of water bodies especially the seasonal lakes and streams in Central and West Africa.
6) Drought condition has facilitated the desertification process in different parts leading to the reduction of the size of the arable land.
7) Agricultural activities decline due to the death of crops leading to the problems of food availability (famine / starvation).
8) Drought conditions force people to migrate from the affected areas to other areas, which are not affected, and this can cause problems of population pressure, land fragmentation and land conflicts.
9) Industries that depend on agriculture can decline like the textile and food processing industries.
10) Women and children suffer a lot in the following ways:
a. They are forced to go long distance search of water and hence they get tired, deteriorate in terms of health, and face accidents like being bitten by snakes, being raped or being killed.
b. Women and children also don’t get time to attend learning institutions since they spend most of the time looking for water and firewood. Performance of girls in school can decline due to lack concentration in school.
c. There can be problems of acceleration of immoral practices since when children and young girls go so much far they can free that they are free of parents attention and decide indulging in misbehavior. Some young girls and boys can use the chance to meet so much far where they are searching for water or firewood and indulge into immoral behavior. This can lead to the spread of HIV/AIDS and unplanned pregnancies among the young girls.
d. Women cannot engage in other activities effectively because of being tired.
11) In some places men are forced to go very far looking for firewood where women cannot reach.
Measures to combat the problem of drought
1) Embarking on a forestation and reforestation programs. The trees add moisture to the atmosphere and hence lead to rainfall formation.
2) The use of proper farming methods which do not deplete vegetation.
3) Control of population should be encouraged so as to avoid the excessive depletion of vegetation.
4) The water conservation centers should be established like dams so as to promote irrigation schemes.
5) Farmers should be given proper education on how to use the resources sustainably to avoid environmental degradation.
6) Strict policies should be instituted so as to restrict the excessive use of trees.
7) There should be introduced the use of alternative energy sources like solar energy, wind energy, geothermal power, water power etc, that are environmentally sustainable.
Flood refers to a period of either high river discharge (when a river overflows its banks because of excess water) or overflow of water along the coast due to extremely high tide and storm waves.
Floods occur as a result of heavy rains that take place in a particular place and they affect so much the lowland areas especially where vegetation has been cleared.
Other floods can occur due to the collapse of reservoirs like dams, emergence of springs, melting of ice and breaking of the water pipes. Also tides caused by the gravitational forces between the earth and the sun or between the earth and the moon as well as the strong waves due to the influence of stormy winds and the earthquakes can lead to floods. This occurs most frequently in the humid regions like equatorial areas due to heavy rains. Nut even in the desert areas, occasional torrential rains can cause flooding.
Factors that can accelerate flooding in lowland areas;
1) Shallowness of the soil due to the presence of the impermeable rock layer just near the surface.
2) The presence of the water table near the surface as a result of soil saturation. When rain water falls on the surface that already is saturated. When rain water falls on the surface that already is saturated with water, floods occur in the river stream since it does not soil down instead it goes to the river channels leading to overflow.
3) Clearing of vegetation accelerates flowing because on a bare surface water runs freely to the streams and end up filling them.
While the developed countries have been witnessing steady increase in food production and supply since the 1960s, the Africa continent has been experiencing an exceptional decrease in food production leading to the rise in number of under bred people. While food production has been declining the number of people has been increasing leading to inadequacy in food supply and hence poor diet, either in amount (quantity) or type (quality), Between 1970 and 1990 there was an increase in availability of food supplies per capital in every developing region except sub-Sahara Africa. It has been estimated that in most developing countries, especially those within the tropics, a person consuming less than 2350 calories per day is likely to experience chronic malnutrition. In 1990, 20 percent of people living in these countries were suffering from chronic malnutrition. Their numbers have increased from 435 million in 1975 to 600 million in 1990 (David Waugh 1998).



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