In Nigeria, State of Osun, the excavating plant, self-powered, self-propelled, dug into the streams, dropped its deeper, scoop shovel, to the stream bottom where it bite and tackled deposition of sufficiently demobilized silt with the weight and action of the hull supporting excavating and lifting mechanism, beneficiation circuit, and waste disposal hopper barge and towage. And the skilful deployment of the dredging craft by its specialized crew, drew unprecedented crowd of bystanders everywhere the work horse operated in Osun.
Of course, yes. None of the dredging fleet has ever been around in Osun under any of the governments in power. True. None of the dredging fleet has ever been anywhere in the State since its creation. With Rauf Aregbesola, governor, State of Osun came the deeper dredge watched closely at work on Osun headstreams; the dredge has a large scoop shovel or dipper that is shaped like a box which hangs on a chain from a long steel beam. The steam beam called derrick according to the craft crew interviewed, is attached to a string mast that swings like the beam and the dipper in a wide semi-circle. ?The mast can be wound and unwound to raise and lower the dipper, and the derrick also can be raised and lowered?, the crew explained, adding, the derrick arm is swung in a semi-circle to drag the dipper across the bottom so that it scoops up the silt. At the Ogbagba, Okookoo, Otoro and Onikoko streams in Osogbo, the State capital, the scrapper teeth of the dredge, that is, the scoop draglines were watched handling the silt from a swing beam. The scoop was drawn forward and held at the proper angle by a long cord to slice the silt as the device was pulled along.
THE OYINLOLA-AREGBESOLA APPROACH TO FLOODS, A NATION FLOOD ? RAVAGED
But the ecoterrorism of the headstreams in the State of Osun was such that actually destroyed Osun environment and intimidated, coerced the previous government of the Peoples Democratic Party?s (PDP?s) Olagunsoye Oyinlola into profound inaction, gross incompetence, open decay, and stalemate, not knowing what to do with the notorious headstreams. And as consequence, the Oyinlola?s ecoterrorism fired up a variety of deliberate environmental crimes against the governed going by the suffering and colossal losses of humans and materials inflicted on the peoples of the State from the yearly flood disaster of Oyinlola?s time as governor, that also brought with it bioterrorism, the supply of polluted water for public drinking.
In other words, before the advent of Aregbesola as Osun governor, the headstreams in the State had sediments that were too unsupportive of growth of economic plants, and had populations of microscopic algae growing on the stream surface that displayed decomposing organic matter derived from nearby waterweed or water grass beds. In particular, findings indicate that no tangible, commercial animals lived in Osun streams, but only had a community of such burrowing animals as polychaete worms, clams, and burrowing shrimps, and many of the worms ingested sediments into the streams that were also feeding grounds for the tribe of wading birds like sandpipers, oyster catchers, and plovers.
Findings show that the Osun headstreams also had a family of water scavenger beetles, feeding on the algae or decaying matter; water scorpions; flying snakes; flying fishes; and perching birds that dart out to capture insects on the wing. The flood-proned headstreams in Osun, in a nutshell, were a site of biodiversity, un-useful in particular to humans who rely on the ecosystem for commercial and recreational uses. Dr. Nasir Owolabi, a botanist, University of llorin, Nigeria, in an interview, in his office explained that the plant rooting zone of such major streams in the rain forest region where Osun State is also situated, is restricted to the active layer, nutrient supplied is limited and secured anchoring for roots is lacking. He added, ?very few kinds of commercial/economic trees could grow in the streams except ones whose active layer is sufficiently deep.?
Further findings indicate that burning of Osun forest and consequent warming of streams incidentally removed the forest canopy, moss, forest litter layers and algae which experts say, play an important role not only as human food but also as fodder for cattle and as fertilizer and raw material for certain industries.
The Osun headstreams before Aregbesola came on board as Governor, most especially the Alagbayun stream in Ife North, Mogimogi stream, Apomu, and Otapete stream in Iragbiji used to experience erosion at certain times due to such factors as storms; depletion of sediments supply; and rising water level in rainy season which alters the existing equilibrium of the streams, made worst by the walk paths, buildings and kindred structures on the stream paths.
Pick discharges of water where infiltration plays a prominent role in the hydrologic cycle and in turn, contributed to Osun streams load by causing channel enlargement, always leaving some erodible materials exposed to the action of the stream plains, to topographically flat surface that stands adjacent to water channel and occupy much of an area constituting valley bottoms. The surface of the streamplain is underlay by alluvium deposited by the associated streams and is partially or totally inundated during periods of flooding. The Osun streams floodplains therefore increases in elevation during a flood event.
So, in Osun, in Oyinlola?s eight years in office, the effects of floods on human well-being were catastrophes. The heights, peak discharges, areas inundated and volumes of flow were catastrophic. While all that lasted in Osun till late 2010, the waiting Governor Aregbesola equipped with his radar, an instrument of weather forecasts to keep track of approaching storms, rains and floods was able to forecast Osun by analyzing radar observation.
Findings indicate that the typical radar display resembles the picture tribe of a television set that shows the echoes as spots of light or an image of the object observed. According to the findings, the size of a unit of radar depends mainly on its use, but they have similar parts-the oscillator, the modulation, the transmit, the duplexer, the antenna, the receiver, the signal processor, the display, and the timer.
Armed with his radar, useful also in flood warnings, and also armed with intelligence reports from his assemblage of experts in metrology, water engineering, computer analysis, and flood control management, the then waiting Governor Aregbesola in far away Lagos, then said in an internew with him, that ?the Osun troublesome headstreams had been the scenes of flood damages and needed his attention? adding also that ?the streams under heavy rainfall destroy crops, cause extensive damage to property, cut transportation lines, disrupts the life of cities and takes a toll in lives. I must say that floods affect man?s struggle to win a living?. Indeed, the Aregbesola imperative of dredging Osun headstreams is the benefit to Osun humans on a sustained yield, focusing on Osun vegetation, Osun animals, Osun topography, Osun peoples, and Osun property and the threats posed by the notorious streams across the State; and focusing on the degradation or pollution of Osun atmosphere, Osun hydrosphere and Osun lithosphere steamed up by the streams alluvia and interaction with specific Osun man-made environmental problems that also include soil erosion and deforestation.
A very close pal of Aregbesola had in fact hinted that raindrops in Osun, reflect beam and shows blips on the screen of the kind of Aregbesola?s radar which also shows the extent and movement of rainstorm that helps forecasts of stream discharge in Osun and flood heights to be made. ?The data on the rate of the stream discharge can then be converted into height -of-stream based also on information of the flow characteristics of the stream channel. In this procedure, the accuracy of forecasts depends mainly on the adequacy of the precipitation?, as findings indicated.
In a snappy telephone chat, Aregbesola emphatically said: ?Osun headwater streams must continue to be dealt with, for their heights, peak discharges, areas inundated and volumes of floods are factors important to judicious land use, construction and/or re-construction of roads, streets, bridges, and water channels and prediction and control of floods?. Yes, of course the stream courses must be re-charted, deepen and widen to increase the channel capacity enough to curtail the potentially disastrous damages from floods. As the struggle to have his mandate revalidated lasted, Aregbesola was simultaneously busy identifying and mapping flood hazard areas in Osun. Infact, flood hazard data so generated by him then, greatly influenced his attitude toward floods, road building, land use and urban reforms and his regulations for Osun flood management.
With Aregbesola?s dredge mechanism, major headstream, so called notorious streams elsewhere, across the State were massively dealt with as the State government in 2010/2011 committed near N2 billion dredging and de-silting Opa, Gbalefefe, Agbara, Kojumole, Olubise stream s, lle-lfe; Adeti, Olutoking streams, llesa, Alagbagun, Otapete and Osun Ojomu streams, Iragbiji; Mogimogi stream, Apomu; Oika, Aro, Aise and Akurin streams, Ipetu-ljesa; Olumesi, Alagbayun and Okookoo streams, Edunabon/lpetumodu axis; Abieku/ Wudewude, Alagbaa, Odo-Owe and Alaagbo streams, Ejigbo; Agbale, Akoro and Ewuro streams, Moro/Asipa axis; Aiba stream, Iwo; and Oloowa and Okun streams, Ode-Omu.
And in 2012, the State re-invested well over N450 million in re-dredging and de-silting the Otapete stream- Iragbiji; Abieku, Alagbaa, Alaagba, and Owe streams-Ejigbo; Olumesi, Alagbayun, Okooko, Agbala, Akoro, Ewuru streams ? Ife North; Aisi, Oika, Akunrin and Aro Ipetu-ljesa; Oloowe and Okun streams, Ode-Omu; Aiba streams and tributaries ? Iwo; Mogimogi and tributaries ? Apomu; Omiru, Olutokun and Adeti streams ? llesa; Opopo, Ogbun, Amunn, Aketi and tributaries ? Jla-Orangun; Esinmirin, Agbara, Opa, Gbalefefe, Ogboku, Osun streams lle-lfe-Modakeke axis.
Before Aregbesola?s dredge, that is, in Oyinlola?s time as governor, though the streams would meander from one side of their beds to another, the streams were used to behave differently, sometimes similarly, at different times but commonly in rainy seasons when large floods enlarged stream channel; when deposits from low flows particularly stabilized by vegetation, restored the shape of a smaller channels; when stream channels could not hold large flows that occur as a result of unusual storms; when a stream cuts through its old bed abandons its floodplain as a result of too much rain at one time; and when bridges, piers, filled land, sand bars and other obstacles disrupt stream flow. Under the Oyinlola circumstances, Osun had suffered from flood events over the year, year in year out, with high-water overflow its natural or artificial banks on to normally dry land, that destroyed homes and property and even carried off topsoil, leaving the land barren. Indeed Osun had suffered huge losses as a result of floods in the past.
Today however, particularly all through the first two years of Aregbesola?s first term in office to now, Osun never recorded any flood case, or had any of its body of headstreams cover normally dry land. Even valleys and gullies that are a common feature in some other States of Nigeria federation, resulting from water erosion and accompanying enormous floods that rush across the surface, never happened in Osun.
Contrastingly, the nation has always been flood bathed. The worst in the recent times was last year?s (2012) flood disaster that swept the length and breadth of Nigeria, with a half of the nation cut shivered as a result of the floods. Lokoja-Abuja highway was cut-off Abuja, Nigeria?s capital city due to the severe flooding of roads and bridges along the highway. Hundreds of residents were rendered homeless by flood caused by torrential rain in Oyo State. A heavy downpour flooded major roads in Ijebu-Ode in Ogun State destroyed houses and other property. One million residents of Kogi State were displaced by floods, cemeteries sacked, schools shut. In Nassarawa State, the flood disaster wrecked havoc. The ravaging flood in Kwara State displaced about 90 communities on the banks of Rivers Niger and Kaduna. People of Niger State were faced with looming epidemics as flood completely took over the water situation that resulted in shortage of portable water. Several communities and well over 200,000 persons were badly affected by floods in Ebonyi State. Floods devastated lives and property in Cross River State. The people of Lagos State counted their losses due to floods that rampaged the State. Homes, farmsteads, roads and bridges were washed away, floods sacked 200 orphans, three electrocuted in Delta State. Houses and cars were submerged and residents displaced, relief camps converted to classrooms, and mother, daughter, drowned in Anambra State. Death tolls rose due to floods in North Central and university sub?merged in Benue State. Floods threatened MTN?s Networks. Commercial banks submerged, residents rendered homeless, property destroyed by floods, and flood ? displaced person died in Edo state. It was a pitiable sight as parents made frantic efforts to evacuate children from floods in Rivers State. Drop in Oil production due to flood that ravaged oil producing States.
Governor?s aide suspended over floods, flood victims turned beggars, and road linking Goodluck Jonathan?s home severed, ancestral homes and palaces sacked in Bayelsa State. Not less than 500 persons, cattle and livestock were dead in the floods that ravaged Plateau State. Outbreak of epidemic from water borne diseases was recorded in Imo State due to floods. Floods over ran private and public buildings in Akwa-lbom State. Houses and commercial houses swallowed up by flood disaster in Abia State. Goats killed family in Enugu State flood. A community cut off in Ekiti State.
Nationwide, by one estimate, about 350 communities were submerged and 1.3 million Nigerians, displaced in 30 out of the 36 States of the federation, such that Nigeria was faced with the worst humanitarian crisis of famine, hunger, inflation, starvation, epidemics and deaths.
SIDE ATTRACTIONS AT VISITS: Fishing, Boating, Flying snakes, Water beetles, Flying fish
Though another rainy season is a fair far cry. During duty- visits to the coastal states of Delta, Akwa-lbom, Cross-River, Bayelsa and River States, fishermen and women were seen collecting fishes in shallow muddy water, using such small tools as knives and hoes, so described as fishing without gear. But at closer watch, some others in deeper water were using long handled tools like thrust, thrown or discharged, clamps, tongs, and raking devices for shellfish harvesting.
A particular fisherman, Cosmos Udoh, attracted attention with his harpoon, composed of a point and a stick joined together by a rope. He described his own fishing device as grappling and wounding which he said, also uses spears, blowpipe, bows and arrows. While findings elsewhere show that rifles and guns are used in fish shooting in technologically advanced nations.
Between Ikot-Epene and Oku-lboku in Akwa-lbom State, women and men who sell dry fish by the bridge-head explained that, ?fishes here are also captured by poisoning with toxic plants and special chemicals or by some form of explosion under water. But quickly added that the device is carefully deployed to avoid transfer of poison to the fish consumers.? Under the bridge, little farther in the water were fishing by natural or artificial bait combined with a hook or a gorge; fishing without belt but with hooks raised and lowered to gig: and fishing by chamber ? traps into which fish easily swims for shelter but escapes, prevented by labyrinths o r retarding devices. While further findings also indicate that fishing could be done using bag nets, kept vertically open by a frame and held horizontally stretched by water current; scoop nets to be pushed and pulled; big stow nets held on stakes or anchors; dragged nets that includes dredges, used mostly for shellfish, may be operated by hand in shallow waters; cone-nets, towed in mid-water between the seabed and surface; seine nets that use towing warps for the catch: drive-lift nets involving driving the fish into the net: and gillnets that catch fish in their meshes.
In Nigeria coastal States visited, fishing was observed to be a lucrative venture. Dr. (Mrs) Celina Ugboagwu, proprietor of Hotline Hotels, Abakaliki, Ebonyi State explained, in a face-to-face chat that all forms of flatfish of the family of demersal living near the water bottom, and such family members of pelagic living in the open water. ?I can tell you that these species are a good delicacy that guests in my hotels relish,? Ugboagwu said. But findings show that aquatic animals, the crustaceans like lobsters, crabs, spiny lobsters, prawns, shrimps, crayfish; the molluskas like the oysters, snails, squid, scallops, mussels, and the octopuses are found, just as certain reptiles like serpents, crocodiles, the amphibians like frogs and many types of norms, coelenterates coral, jelly fish, and sponges are some of the mammals sought after at our riverside by commercial fish men.
But why the interest in fishing particularly in the coastal States visited? Cold blooded aquatic vertebrates are of interest to humans across the climes for their relationship with and dependence on the environment as findings show that fishes are a moderate and important part of the world?s food supply. The reason is in delicate balance with the biological, chemical and physical factors of the aquatic environment. Findings further show that fishes are also useful in disease control. Dr. Miss Ene Okon, graduate of medicine, University of Calabar, on housemanship in Bayelsa State General Hospital, stated in a face-to-face chat that fishes as predators on mosquitoes larvae help curb malaria and other mosquito-borne diseases. As findings elsewhere show, fishes are valuable laboratory animals in medical and biological research. There are also aesthetic and recreational reasons for an interest in fishes. Millions of people keep fishes in home aquarium for the simple pleasure of observing the beauty and behaviour of animals otherwise unfamiliar to them. Sport fishing is another way of enjoying the natural environment, also indulged in by millions of peoples every year. Interest in aquarium fishes and sport fishing support multi-million dollar industries across the world.
In the riverine States visited, fishing is carried out on both small and large-scale commercial basis, using vessels, the fishing boats, of different types of local designs dictated more by the fishing methods, but with some element of standardization set by the Food and Agricultural Organization of the United Nations.
The boats, at the harbor in Port Harcourt, capital of Rivers State, vary considerably in size, weight, durability, stability, ease of propulsion and even in shape, as though they are characterized by lightness, maneuverability, versatility, ease of repair, and relatively inexpensive. Such boats as rowboats, canoe, sailboats, motorboats, ferryboats that are deep and narrow, wide and flat, slow and fast, light and heavy are observed to have been constructed for the functions they perform. King Airhiaviabare, a boat building technician said, ?here we strive everyday to improve efficiency by building vessels that have higher catching power, small crews and reduced operating costs, yet we match our vision against safety concerns.?
On-the-spot findings show that wood is the major material for boat building and the earliest boats were made of hollowed logs. As demand for larger sizes exceeded the size of single trees, carvel and lapstreak planking and sheet or molded plywood are the commonest types of wooden construction this modern time. However, as further findings indicate, molded fibre glass, metal sheath lining and aluminum have gained greatly in popularity as boat building materials, surpassing wood in the number of hulls produced. Their original application was for small outboard boats and day sailors, but larger and larger sizes are now commonly built from both materials. There is also limited use of rubber and rubber-like synthetics, plastic foam, canvass concrete also known as fibrocement and steel in boat construction.
Others in the fleet of boats for fishing, and for technical, military and security purposes would include tugboats, hydrofoils, hovercraft, life boat, speed boats cruiser, canal boats/narrow boats as well as catamaran, paddle steamer, container ship, ocean liners, aircraft carriers and oil tanks that are ships, not boats. In Port Harcourt seaports, it was observed that hydrofoil boats are lifted above the surface of the water after reaching a certain speed by wing-shaped foils that extend under the water on arms. According to Odemgbo Afam, a Nava Rating, at the Cross River State, Calabar seaport, reduction of friction, or drag, by lifting the hull out of the water increases speed and makes for a smoother ride. The application of hydrofoils has been largely limited to passenger service and naval patrol. However, hovercraft is supported just above the water, mud or even dry land by a cushion of air ejected from the hull. They are propelled by directional air jets.
In Nigeria?s Bayelsa, Delta, Rivers and Cross River for instance, men and women most commonly depend on wind and water currents and their muscles to move boats. Poles or oars and paddles are used to push rafts and canoes. In the riverine areas particularly the creeks of Southern Ijaw of Delta State, men and women, young and old know how to sail, letting the wind blow them along by their push against square sails held upon poles or masts. Paddles used to propel boats are in several shapes, depending on application, and most commonly from maples or spruce woods. The beavertical or oval blade is commonly adopted by bowman, and the slightly rounded and square-tipped blade by the stern paddler because it affords more surface for steering and maneuverability. Racing paddles have a wide and long blade to permit maximum thrust, or ?catch? in the water. The blades of double-bladed paddles are spoon-shaped or flat. For racing, a paddle with a one-piece shaft is preferred, for general use, a shaft with a ferrule joint in the middle for convenience in stowing is advisable. Grips are either pear-shaped of t-shaped, the latter being more comfortable and secured for the beginner. Overall length of the paddles varies with the height of the paddler, the kind of propulsion demanded, type and size of the boats and number of paddlers.
At Calabar Naval base, the distinction between ?boat? and ?ship? was sharply made and emphasized. A senior sailor, Nasir Abdullah stated that ?if a navy vessel is commissioned, it is a ship, and if it is attached to a station base, larger ship or an organization of vessels such as a squadron, it is a boat?. From Calabar, the Navy?s boats include patrol craft, the armed motorboats used on river patrol, land crafts, riverboats, personnel boats and such specialized types as whaleboats used as workboats by larger Navy vessels and a gig, the launch reserved for a ship?s captain. The personnel boat of an Admiral is the admiral?s barge.
Long before boats became important in recreation, they were valuable for man for many essential tasks. Findings show that boats such as lifeboats carried by ocean liners are important to marine safety. The US Coast Guard uses many small crafts in patrolling coastal waters. Special designs have been developed for working in dangerous inlets. Surfboats for launching directly from the beach are important in lifesaving. They are built very strong and extremely sea worthy. Fire boats and harbour-police craft are designed for their special functions, fit into the marine world.
Generally, man has used watercraft called boat as an important factor in transportation, warfare, and exploration. In the coastal States visited, the boats are not only the trawler type which pulls a long net through the bodies of waters to catch fish. The boats are also widely used for economic and industrial purposes including prospecting, mining, lumbering and surveying and are also valued for a number of government projects relevant to parks and forests. The findings indicate that such watercrafts as canoes, small boats have two seats and two thwarts, and they range in length from 6 to 18 feet (1.8 to5.5 meters) Boats that are powered by motors, sails or both can run from about 12 feet (3.7 meters) to 150 feet (46 meters), or longer in length. While motorboats, mostly less than 26 feet (8 meters) in length are powered either by an inboard engine contained inside the boats hull, or an outboard motor which is mounted on the stern (back) of the boat. Some motorboats combined these features, with the engines inside the bull and the driving years and propellers within a unit at the stern. The twin propellers and rudders make motorboat more maneuverable than a boat with only one propeller. A luxurious motorboat with a length between 40 and 100 feet (12 ? 30 meters) called a motor yacht or mega yacht having several cabins with bunks, bathtubs/showers, a head toilet, a well equipped gallery and dinning and a recreational area both on deck and below. Generally, the yachts usually constructed of aluminum or fibre glass have two engines and sophisticated electronic navigation equipment including radar, radio telephone and electronic satellite.
According to the findings, among the most popular type of motorboats are water -skiing boat, fishing boats, and day-cruising boats called runabouts. They generally range from 16 to 26 feet (5 to 87 meters) in length. And sailboat with two hulls called catamaran, one with three hulls, the trimaran, are both called multi-hulls and tend to be faster than monohull (single hull) boat. Boating can also be for personal pleasure and this has become the main use of boats in the US and Canada. Increased leisure time and earnings contributed greatly to the growth of American boating as did the availability of many bodies of water, some artificially formed.
Pleasure boating is also popular in England, Western Europe, Australia and New Zealand, but in much of the rest of the world, it is mainly for the reach. Some people enjoy paddling a canoe across a lake, while others enjoy fishing from an outboard boat or rowboat. Many others prefer to glide across the water on a sailboard or in a sailboat, while another large group prefer to fish or to speed along in a motorboat.
More people own recreational boats for sport fishing than for any purpose, although a boat for fishing can also be used for water skiing, skin driving, camping, or simply sight-seeing and joyridding. Mass-produced stock boats using outboard motors for power have brought those activities to millions of people. Crushing from port to port in certain cruisers or small boats with auxiliary engines or camp crushing in small spen boats is the simple most popular pursuit. Many specialized boats vary greatly in look and functions, and the simplest are the portable boats that can be kept at home and transported by cars. These are boats that can be knocked down and folded, inflatable rubber, or plastic boats, and rigid boats known as cartoppers. All these are small and are restricted to protected waters and are propelled by paddler, oars, small board motor or sail, a combination of these; these small sail boats known as board boats spread the fun of boating among many more people. They are ?bathing suit? boats as the occupants invariably get wet. Capsizing is common and is no problem as it is easily righted. But big pleasure boats, too big to fold, are transported by a trailer to many different bodies of water, like a house boat also for use in sheltered waters and feature large living and sleeping spaces designed into the hull and deck structure.
Other side attractions in the coastal State visited included the flying fish that does not fly in the sense of flapping its wing ? sized fins, but actually glides. The fish was observed building up speed underwater, swimming toward the surface with its fins folded tightly against its streamlined body. Upon breaking the surface, the fish spread its enlarged fins and gains additional thrust from rapid beats of the still-submerged tail. When sufficient speed has been attained, the tail is lifted clear of the water and the fish is airborne, gliding a few feet above the surface. Findings show that the flying fish can make several consecutive glides, the tail propelling it up again each time it snicks back to the surface. Flight the fish is primarily a means of escaping predators.
Yet another side attraction particularly at Ayakoromor, an Ijaw community, Delta State is the flying snakes, slender arboreal sn ake, long and black or greenish with yellow or reddish markings, and is able to glide short distances, like the flying fish. But as further findings show, the flying snake does the gliding through the air by straightening the body and drawing up the ventral scales to make the underside concave, and the snake is active by day capturing rodents, bats, birds and lizards.
But at Kpata, Adaukola, Gaduma, and Ganaja communities of Lokoja, Kogi State were water scanvenger bettles, ?predominantly aquatic insects of the family hydrophilidae, having smooth, oval, dark-brown or black bodies and short, hairy chibbed antennae, commonly found swimming in marshy water by moving the middle and the hindless on each side? according to Professor Tijani Abukarkar, an entomologist and lecturer, University of llorin, in a phone interview.
HYDROLOGY, METEOROLOGY: NORTH-SOUTH NIGERIA
While flood was the feature in many States, Nigeria South and Nigeria Middle-belt in the year under review, most states up-up North of the country have always had near deficiency of water in the ground, streams, lakes and reservoir; an imbalance of the hydrologic circle? said Daniel Oghene, a Professor of hydrology, University of Port Harcourt. In an interview in his office Oghene stated that in the circle, water vapour enters the atmosphere by evaporation from oceans, lakes and ground surfaces and by transpiration from plants; and water is returned to the earth in the form of rain, or snow as elsewhere in the globe. Some of the water, he said recharges the soil moisture, some accumulates in the bodies of water and some runs off to the oceans. Thus drought can result simply from a deficiency in precipitation over a period of time or it may be caused or intensified by excessive evaporation and transpiration. The normal difference between precipitation and evapotranspiration is a mean of dryness or wetness of climate.
The case of meteorological differences between the flooded and non-flooded or flash-flooded Nigeria could respectively be explained away by water surplus discharged through streams and rivers all year-round in the South, and by drought presence in one season of the year in the North-the desert, most commonly the area with arid climate, sparse vegetation or no vegetation, angular landforms and absence of full-blown rivers to support either a forest or a complete grass cover, and meagerness or uncertainty of precipitation
Findings show that in the North, the amount of rain does not equal the potential evaporation, even the small amount that does fall is subject to great variations from year to year. Rain comes at infrequent and irregular spaced intervals. Wide spread rain is uncommon. Rain is localized, storm is localized, but not everywhere, but when it occurs, it is often so violent as to cause extensive damage, destroying villages, houses and farms. However, the storms replenish the scanting supplies of groundwater that makes life possible (or is it mildly miserable) in the desert. The detail of the desert is not masked and is the more striking, unlike the surface in the South where plentiful rainfall creates a heavy cover. ?But on the occasion of a very rare gently shower in the North, the rain barely moistens the surface and it?s soon evaporated. At times, clouds form and one can see rain beginning to fall from them, only to be evaporated before it reaches the ground,? Oghene explained further.
Cloudburst is the usual in-thing in the North, associated with thunderstorms. The up-rushing air currents of the thunderstorm support a large amount of water in the form of raindrops, and as the air currents suddenly cut off, a mass of rain quickly falls over a small area. Stream beds become torrents and rivers form in valleys that are usually dry. During a cloudburst, more than 1 inch (2.5 centimeter) of rain many fall in just 115 minutes. Further findings show that the causes of drought are an intractable problem in the science of meteorology. It results from a lack of precipitation; it is intensified by high temperature, strong wind, and low humidity, all of which increases the loss of moisture by evepotranspiration; and it can be caused by abnormally low sea-surface temperatures, as for example, on the West Coast of Pero, there is usually little precipitation except in the feeble form of drizzle. Low sea surface temperature off the coast stabilize, the atmosphere so that the vertical air currents needed to produce appreciable precipitation are suppressed.
In the North, the shifting of normal cyclone, low pressure storm system, tracks across a region, that leaves some areas in the region without their normal precipitation for protracted periods. Associated with the shifting of storm tracks is tendency for the affected areas to be dominated by high pressure systems in which cold, dense air sinks and is warmed by compression, prevailing condensation and precipitation. This is the cause of perpetual drought in the earth?s great deserts, North, Nigeria inclusive.
But the floods in the North Central Nigeria, last year 2012, better called flash floods, as most rivers and streams in the area rose suddenly and overflowed due to heavy rains from thunderstorms, reportedly caused great destruction. Soil carried by the flooding was deposited in large amounts at the bottom of rivers, including River Kaduna raised the riverbeds and increased the flooding.
In the South, especially, South-East, Nigeria, what is almost everywhere announcing the potentials for flooding are the channels, valleys and gullies carved by enormous flood that rush across the surface. In many areas like Iriri community, Bobougbere community and Elohim community, both in Delta State for instance the waters seemed to have escaped suddenly from underground. The valley networks in the places visited in the flood affected States look more like river system on earth, showing mostly ancient features. While the gullies, most of which lie at high latitudes may have resulted from a leakage of small amount of ground water to the surface.
Findings elsewhere indicate that rain, the precipitation of liquid water drops is the sole supply of the earth?s rivers that, also includes smaller streams, ends where they flow into other rivers, desert, basin, ocean or lake. Rivers are used for transportation and trade, and valuable for agriculture. In the North, farmers use river water to navigate their land, dig irrigation ditches to carry water from rivers to farmland. As a source of power, the energy of flowing water at waterfalls and other steep places along a river can be captured and used to drive machine and generate electric power. But costly dams and other structures are required to harness water power.
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Short URL: http://www.osundefender.org/?p=96330
Source: http://www.osundefender.org/?p=96330
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Public release date: 28-Mar-2013
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