The northern parts of the country and the Sahel zone are being invaded by the aggressively-advancing Sahara desert vis-a-vis desertification and Savannah grasslands. The disasters are now aggressively-moving southwards. Wind storms, sand dunes, extreme aridity, drying out of water or major falls in levels of surface waters, laryngeal ailments such as cough and catarrh, heat waves, meningitis, blindness, skin diseases etc. have become severe environmental scourges to the inhabitants of the areas. Many people have lost their agricultural lands and homes to sand dunes; water resources, animal husbandry and irrigation have been lost. These hazards have caused massive migration of people with their farm animals and property southward.
Prof Boniface Egboka
The vagaries of extreme climate change and anthropogenic activities, particularly by humans such as overgrazing by cattle, horses, goats, sheep etc. and bush burning by herdsmen exacerbate the incidences of desertification and Savannah encroachment into parts of Nigeria. Unless urgent remedial actions are taken, Nigeria will have an expanding desertified and Savannah lands. Most of the lands and socioeconomy will be destroyed in the years to come. Climate change heralds high temperatures and extreme aridity. These result in excessive negative environmental impacts such as poor humidity, drying up of surface waters (springs, streams, lakes, wetlands etc.), loss of grass and shrubs of diverse flora and fauna etc. The population of livestock and their herdsmen are too many. These animals are vicariously-moved from one environment to another. As they are moved, they massively-feed on farm crops, vegetation and consume large volumes of water where available. This happens all the year round as itinerant herdsmen with their families move. As these events in combination with other harsh factors happen over the years, the environment is gradually-desertified from Guinea Savannah to Sudan Savannah and, then, into desert conditions. This is the desertification cycle that had happened over the years in the Sahara and Sahel zones of Africa and that continues to happen till this day. The herdsmen instead of using knives, bows and arrows, now, they are armed with modern AK47 rifles where if the need arises, the rifles are freely-used for killing and maiming as in Benue and Enugu States in recent times. The animals are led into farms to feed on fresh vegetation and farm crops and later into village streams to drink after feeding thereby polluting the waters as well. These herds of rampaging animals and their owners are so many in number that you can find them in many States and communities in the south. Close to the end of the dry season, the herdsmen set off massive bush burning to clear the old vegetation in order to create conditions for sprouting of green foliage at the onset of the rainy season for their animals. This vicious cycle of devouring vegetation by animals and burning the remnants by herdsmen for new foliage, annually, destroys the Biologic and Hydrologic environment. These processes have contributed to turn parts of rainforest belt into Savannah grassland, now, aggressively-advancing into southern parts of Nigeria. This will be accelerated by the impending Grazing Bill being threatened to be passed into law in National Assembly. This will be a Bill for desertification to overrun the middlebelt and move at a faster rate into the south. There are ranches in Arab, European countries and the Americas for millions of cattle, goats, sheep etc. Nigerians should create ranches for herdsmen and their animals.
Deserts constitute about 25% of the earth’s total landmass. Desertification is the process of allowing natural or man-made activities to make parts of the earth’s surface acquire characteristics of a desert environment. Deserts have very low rainfall, high temperatures, extreme dryness, windstorms, sparse or no vegetation, scanty population and poor human development. Poverty, meningitis, laryngeal diseases like cough and catarrh, blindness or eye infections due to dust storms etc. are some of the pervading environmental scourge. Heat waves, wind and dust-storms, infrequent flash floods etc. make the desert and Savannah environments life-threatening. Excessive aridity is characteristic of deserts. Outcrops of groundwater or oasis may occur. Rural and urban communities may sparsely-exist or be non-existent. Problems of water scarcity are endemic. People cluster near streams and oasis for domestic water supplies and agricultural purposes. Desertification is a calamity that is virtually resisting all efforts to contain. It mostly occurs in the semi-arid zones of northern Nigeria, covering the extreme north, from latitude 12oN to the boundary lands with Niger and Chad Republics. In recent years, the arid and semi-arid regions or the Sahel and Sudan Savannah respectively are witnessing a severe and detrimental drought. This has unleashed devastating and frequent occurrences of protracted droughts that have accentuated the process of desertification, Savannah encroachment and environmental degradation. The desert environment is most inhospitable and is fast deteriorating and advancing southwards and nationwide. The continuously-plummeting agricultural production and population growth have accelerated the process of soil degradation through impeded drainage, erosion by wind and water, scanty rainfall, improper soil management, indiscriminate and extensive deforestation, environmentally-incompatible farming techniques, excessive overgrazing and largescale bush burning. The continued decline in agricultural production constitutes a major problem that accentuates widespread poverty, hunger and diseases. Ignorance of farmers on judicious management of natural resources results in ecological imbalance that culminates in rapid desertification and Savannah development. Adoption of appropriate soil conservation measures and management strategies, judicious, scientific and environmental management, sustainable farming and greenbelt development would improve agricultural productivity on a sustainable basis and preserve a stable ecosystem.
The arid and semi-arid environments are widely-expanding through desertification. The northern parts of the country and the Sahel zone are being invaded by the aggressively-advancing Sahara desert vis-a-vis desertification and Savannah grasslands. The disasters are now aggressively-moving southwards. Wind storms, sand dunes, extreme aridity, drying out of water or major falls in levels of surface waters, laryngeal ailments such as cough and catarrh, heat waves, meningitis, blindness, skin diseases etc. have become severe environmental scourges to the inhabitants of the areas. Many people have lost their agricultural lands and homes to sand dunes; water resources, animal husbandry and irrigation have been lost. These hazards have caused massive migration of people with their farm animals and property southward. They cause socioeconomic dislocations to their hosts and lands sometimes occupied by force. This may, sometimes, result into conflicts that precipitate injuries or fatalities. As the desert moves south from the Sahel-northern borders and fringes, it pushes the Savannah grassland in its frontal regions into the more southerly environment. This is why the middlebelt areas are almost-fully Savannah while also experiencing hazardous desertification effects. Frighteningly-enough, some southern States like Enugu, Ebonyi, Anambra, Delta etc. that formed part of the then luscious and evergreen Rainforest Belt of West Africa about thirty years ago, are now being enveloped by the Savannah grassland. Over 80% of the country that includes parts of the south are usually-covered by wind-blown dust from the desert during the harsh period of harmattan from the month of October to March. There are socioeconomic discomforts, dislocations in communications in land/air travels. Savannah has advanced into parts of middlebelt. Desertification agents include uncontrolled population growth, urbanization, deforestation, irrigation agriculture, bush burning, etc.
Natural causes of desertification are related to events of the climatic and sociological conditions prevalent in the area, namely, high temperatures, low precipitation to excessive evaporation, aridity and deforestation. The wanton destruction of forest resources adversely-affects the micro- and macroclimatic conditions of an area. These are reflected through the widening and encroachment of desert conditions and Savannah advancement that are accompanied by heavy soil loss through wind erosion and flash floods. Man-made or anthropogenic causes of desertification include population growth, urbanization, bush burning, over-irrigation, overgrazing and deforestation. Increase in population growth signals increased human activities that require more building materials for shelter and agricultural lands to grow more food for which more lands are cleared. Deforestation results in low infiltration capacity for water into the soil, increased run-off and severe erosion by wind and water. It increases the rate of wind erosion and desertification. Extensive land use for agriculture and urbanization are strong contributors to desertification. Fire and bush burning destroy lands and vegetation, make soils fragile and lead to dry atmosphere. Too many building of large dams causes excessive loss of water. The nomadic life of cow breeding and overgrazing cause desertification. Abundance of cattle in sparse vegetation conditions imposes a burden of loss of flora and fauna. Even multiple trampling on soils by many cattle also causes harm to lands and vegetation and enhances the process of desertification. Human activities, animal-grazing, cutting of trees, negative farming practices and wrong land use techniques that are beyond the carrying capacity of the soils decimate vegetation and create instability. The semiarid grasslands create the environment for true deserts to expand.
In Tertiary times (over26 million years ago), the sea began to rise again through transgression. Large inland seas, occupying broad depressions covered parts of Nigeria that are, now, Sokoto and Borno States resulted. The Quaternary period (over1.5 million years ago) traces the events of the withdrawal of the sea in the south as it retreated approximately to the present shoreline of the Holocene or Recent period (over 10,000 years now). The Sokoto Lake dried up completely while the Borno Lake or Lake Chad shrank to its present size and is still shrinking at an alarming rate. In the last 30 years, Lake Chad has been reduced in size to 2,000km2 from its former size of about 25,000km2. It follows that it has lost about 23,000km2 of its areal extent in 30 years; the waters of the lake may finish in a few years. Geologic evidence showed that southern Nigeria witnessed at least two major marine transgressions in the Mesozoic era (over136 million years ago). It is believed that between these two transgressions, a narrow strand of water that followed the Benue and Gongola valleys connected the Tertiary Sea in the south with Lake Chad in the north. In the Tertiary times Sokoto, Borno and southern areas of Nigeria were covered by the sea. These areas, except for a small patch of the area now occupied by Lake Chad, have lost all their waters to land as a result of tectonism and regression of the sea. Salt is collected from the Quaternary sands of Lake Chad, an evidence of desert encroachment that resulted from the evaporation of the waters of the drainage basin. However, the Palaeogeologic History and the present-day environmental changes have profound influences on the Geologic-cum-Geomorphic features of parts of northern Nigeria, the desertification processes, the dried-up Sokoto Lake and the drying up Lake Chad, the southward advance of the Savannah/Sahel region and Sahara desert. We are forewarned!
*Prof Egboka, UNIZIK, Awka, Anambra State; E-mail: email@example.com