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LAND USE CONTROL AND N A T U R A L RESOURCE M A N A G E M E N T IN N I GE R I A AREOLA, O . Ibadan * and OFOMATA, G.E.K., Nsukka * *

Abstract: In Nigeria, increasing evidence indicates a deteriorating man-land relationship. Negative changes in landscape quality, lowering both the productivity and aesthetic quality of the natural environment, may have serious effects on the nation's economy. In rural areas, declining soil fertility and soil erosion threaten the ability to produce sufficient food. In urban areas, competition for productive agricultural land has led to its conversion to urban uses. Earth materials required for urban development have been obtained by widespread landscape destruction. Expansion of urban areas into sensitive valley, marsh, and lagoon environments has led to an increased frequency of urban floods and flood damage. A developing conservation ethic must be accompanied by a practicable framework for land use control. In Nigeria's modernization, emphasis has been on economic growth. In the face of aggressive economic considerations, ecological perspectives on resource utilization have been relegated to the background. Yet the country is seeing increasing evidence of disharmony with nature, such as food shortages. More seriously, many parts of the country have experienced natural hazards, including the Sahelian drought of 1972--73; the increasing incidence of floods in such urban centres as Lagos, Warri and Ibadan; and the destruction of cocoa and arable farmlands by bush fires in southwestern Nigeria. More subtle, but equally significant, is the continued deterioration of soils through nutrient depletion and erosion. In urban areas, productive land is lost in the search for earth materials for construction and in economic competition from urban and industrial uses of land. An increasing incidence of urban flooding indicates a fundamental disharmony of land use in watershed areas and in the city itself. In the absence of planning, the use of land and the exploitation of natural resources have been virtually unguided and uncontrolled. Furthermore, there has been little improvement in traditional land and resource management practices, in spite of three national development plans. The failure of the plans to effect a marked improvement in the social and economic well-being of the majority of the people is in a sense a reflection of the inability to harness the

*

Dr. Olusegun AREOLA, Lecturer in Geography, University of Ibadan, Ibadan, Nigeria.

* * Dr. G.E.K. OFOMATA, Professor of Geography and Dean of the Faculty of Environmental Studies, University of Nigeria, Nsukka, Nigeria.

available natural resources for balanced development of the economy and an equitable spread of development throughout the country. Left to themselves, individual land or resource users are guided more by considerations of profit maximization than by the need to maintain the aesthetic quality and the balance of nature. While the 'oil boom' has vastly increased the spending power of the nation and provided funds to implement numerous development projects, it also has enabled Nigeria to embark on major projects, some of which have been established without due regard to the ecological condition of the land. The nation's recently-found wealth seems to have established the type of feeling of supremacy of man over nature that was generated in the Western World by the inventiveness and technological accomplishments of the industrial and agricultural revolutions in the 18 th and 19 th centuries. Nigeria is endowed with a vast resource of land. Of the total land area of the country (approximately 923,768 kin2), about 9 % is yet unused, 35% is devoted to arable and permanent crop cultivation, and 56% to forestry and permanent pastures. Apart from the actual land now under cultivation, it is estimated that as much as another 31 out of the 56% classified under forestry and permanent pastures constitutes potential agricultural land, since it is neither under forest reserves, nor under permanent pastures. Thus, Nigeria has a high proportion of actual (35 %) and potential (31%) agricultural land. The agricultural potential of Nigeria is further highlighted by climatic zonations which make it possible for a wide variety of crops to be grown during the greater part of the year, varying from root and tree crops in the south to grains and assorted vegetables in the north. To assure successful agriculture in the country, effective land management is required, including efficient soil and water conservation measures to negate environmental deterioration.

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To ensure that the scale of human population and of its intervention in the environment do not steadily increase imbalances in man-environment relationships, Nigeria must be quick to learn from the experiences of the technologically advanced countries and ensure that its environmental management is enlightened and properly guided. Unless this is done, Nigeria will inevitably move to the unenviable position of most of the technologically advanced countries, characterized by the observations of STRONG (1972, p.76): "The scale of the present human population, the scale of its interventions in the natural system, and the scale of these interventions on that system have grown at such geometric rate that the historical man-nature relationship has been turned on its head. Instead of balances we have imbalances. Instead of an order of things we have things out of kilter". Here, we describe recent Nigerian experience in the management of land resources, focusing first on rural areas, and then on urban land use problems. Declining soil productivity and accelerated soil erosion contribute to food supply problems whose significance is indicated by programs such as the National Accelerated Food Production Project and Operation Feed the Nation. In many ways, rural land use problems are related to urban dynamics. Urban areas, for example, encroach on the countryside, and draw upon rural areas for mineral and food resources to sustain their growth. Our second focus, therefore, is upon urban areas and the impact of their development. Whilst despoilation of open space, waste disposal, sanitation, housing inadequacy, and many other problems infect the urban landscape, we discuss urban floods as diagnostic of the man-land imbalance that occurs in Nigerian cities.

Declining Rural Productivity In a predominantly agricultural nation, it is ironic that high prices and shortages should characterize Nigeria's food supply. The situation may be worse in rural areas for foodcrops are usually despatched to the urban markets to earn money to meet rising expectations. The decline in agricultural productivity being experienced in several parts of the country is as much a result of the general lowering of soil productivity due to increased pressure of use as it is of the drift of young, able-bodied school-leavers and middle-aged people into urban centres.

Soil Depletion The predominant system o f agriculture in Nigeria is shifting cultivation w i t h bush fallowing. The productivity o f the system depends very much on the length o f the fallow period during which the soils are allowed to regain the fertility lost during cultivation. Unfortunately, in recent times, the fallow period has been shortened in many parts o f Nigeria as a result of the need to produce more food to feed the growing population and the ever-expanding urban markets. The shortening o f the fallow period has meant that the soils are not quite f u l l y restored before they are cultivated again. In the absence of animal manure or chemical fertilizers this has resulted in general soil

deterioration such that not only can the soils not support high crop yields, the fallow vegetation communities themselves are less vigorous and restorative of soil fertility status. In the past farmers depended on the density of vegetation cover and the emergence in the fallow community of certain species of plants to ascertain the land's readiness for recultivation. Most farmers still use these criteria but the indicator plant species now take much longer to ermerge, if at all. This taxes the patience of many farmers; at various times they cultivate portions of the land for a season, ostensibly 'to find out if the land is ready for cultivation.' Such trial cultivations only impede the natural restorative fallow process. The disappearance or the delay in the emergence of the indicator plant species in the successional development of the fallow communities is evidence o f soil impoverishment and their slow rate of regeneratiod. The reduced efficiency of the natural fallow in restoring soil fertility under present management conditions is particularly evident in the derived savanna zone (Areola 1977). A typical example is the Ibarapa Division of Oyo State which produces about 10% of the Ibadan food supply (Daly, et. al. 1975) and also supplies food to Lagos and Abeokuta. This is an ecological zone where farmers do not traditionally keep animals but maintain forest farming practices. Their response to the pressing need to provide more food has been to drastically reduce the fallow period and lengthen the cultivation period by growing less demanding crops (cassava, pepper) on land earmarked for fallow. This is unlike the situation in some parts of thi~ Sudan savanna, such as the Kano densely populated region, where the farmers have responded to the same problem by adopting animal manuring and crop rotation techniques (Mortimore 1967). Establishment of predominantly grassland vegetation in the derived savanna zone in the present century has brought in its wake the phenomenon of annual bush burning on a large scale. Thus in Ibarapa Division, as elsewhere in this ecological zone, the fallows are burnt every year and the land is exposed to intense insolation and the heavy rains of the early rainy season. Under these conditions soil desiccation and deterioration have set in which further reduce the vigour of the fallow vegetation and its ability to restore soil fertility (Areola 1978).

Soil

Erosion

The incldence of soil erosion has been reported in several parts of the country under different geological, climatic and soil conditions. STAMP (1938) attempted a general review of the problem, while GROVE (1951 and 1952) undertook a special study of the subject in parts of the former Eastern and Northern provinces of the country, and summarized his views on soil erosion in the whole country in 1956. OFOMATA (1964, 1965, 1973, 1975 and 1976b) has also studied the phenomenon in detail in parts of Southeastern Nigeria, and OLOGE (1971 and 1973) has carried out similar studies in parts of the savanna zone of the country.

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Soil erosion can be regarded as a geomorphological process, whereby the surface layer of weathering rock is loosened and carried away by wind or running water and a lower horizon in the soil is exposed. Under natural conditions, transport of material downslope or in the direction of the wind usually goes on intermittently, and each movement is so slight that erosive processes are very slow and appear to be continuous. Normally, soil formation is able to keep pace with this slow attrition, and, as GROVE (1956) has indicated, "the soil profile as a whole shifts downward and the thickness of the topsoil is maintained and, for most purposes, the soil under an undisturbed cover can be regarded as being in a steady state." Man needs the soil for cultivation and has to clear the bush or forest for farming. He also burns grass and trees and grazes his animals. Each of these activities exposes the soil to the elements and usually - but in varying degrees from place to place and depending on the existence of other favourable factors - to "accelerated" soil erosion and deterioration.

plateau surface (at Udi) gives about 8 0 % of "coarse aggregates" (silt and clay), compared with 66 % of coarse aggregates and 15 % of fine elements at about 1.25 m below the surface at the same sample site. Near Agulu, the corresponding figures are 72 % (coarse aggregates) and 12% (fine elements) on the surface; 63% (coarse aggregates) and 23% (fine elements) at about 2.10 m below the surface. Wind erosion occurs more generally and more frequently in the northern parts of the country, but is limited in both time and place in other parts. Some o f the materials removed by the wind reach the southern parts of the country by way of dust-laden winds - the North Easterly Trades - especially during the period of the "harmattan".

Soil Conservation Efforts Soil erosion is a disastrous form of environmental degradation. To combat it effectively, one needs to know the factors responsible for its inception and development; one also needs to know the types of erosion which exist and the spatial distribution of those types. The 'factors o f soil erosion easily resolve into two components - geologic (natural or physical) and anthropogenic (human or "accelerated"). Close study has, however, revealed that, at least for the developing nations o f the world, the human component in soil erosion is often exaggerated while the part played by physical factors may be underestimated (Ofomata 1965 and 1975).

What easily attract and retain one's attention are the gully types of erosion - because of the remarkable and aweinspiring impression they leave on the surface of the earth. Good examples of gullies are widespread in south-eastern Nigeria, especially in the Agutu-Nanka, Nsude, Nsukka and Orlu areas of Anambra and Imo States. Other examples, on a much smaller scale, also exist in parts of northern Nigeria, especially on the los Plateau and around Zaria. Yet, gully erosion is only one aspect of the soil erosion phenomenon, and one which has affected the smallest area of land in the country. In the case of southeastern Nigeria, active gully erosion presently affects only about 0.6 % of the total land area, while all types of gully erosion occupy a little less than 2 %. The situation is worse in Anambra and Imo State, where comparable figures are 1.90 % and 5.40 % respectively. Much more pernicious and highly detrimental to agriculture is sheet erosion which often goes on unnoticed due to its gradual, constant and uniform action, finally resulting in a complete removal of the arable parts of the soil, thereby ruining the land. The topsoil is gradually swept clear of its finer elements and plant nutrients, and only coarse materials are left behind. The granulometrical composition of a typical soil sample from the Udi-Nsukka

No matter the type of soil erosion which operates, the results, in terms of relevance to soil conservation, are twofold: general decrease in soil fertility (following continuous sheet wash and wind erosion) and d i m i n u t i o n o f cultivable land as a result of the expansion of gullies. The need to arrest this wasteful trend in soil loss has been widely recognized and various soil conservation measures have been taken at various levels to deal with the problem (Grove 1951 and 1956; Ofomata 1964, 1973, and 1976b). In spite of these attempts the problem of soil erosion is steadily increasing, and it is our contention that existing conservation efforts in the country are inadequate. The hazards of soil erosion have forced those directly concerned - both individual farmers and government departments - to attempt measures aimed at controlling the spread of the phenomenon. These soil conservation measures have taken various forms, but the ultimate aim has always been to limit (if not to arrest) further loss of land and deterioration in soil fertility. Both curative and preventive measures have been adopted by conservationists to combat the phenomenon. On the curative side, the common lines of action depend on the type of erosion involved. For gullies, the attempt has always been towards preventing as much r u n o f f as possible from reaching the gullies, as well as on stabilizing the slopes. A combination of ridging, contour ploughing, bunding and the construction of side-drains leading to soak-away pits (sumps) has usually been applied. For sheet wash, the emphasis is on reducing the extent of bare soils in any area and by planting such areas to grasses, such as bahama grass, and shrubs, such as Acioa barter/, as well as other local varieties. Wave bedding is also important to either of the above measures. In the case o f wind erosion, emphasis is again on limiting the extent of bare soils and providing wind breaks (trees, shrubs) to check the process.

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On the preventive side, where the incidence of erosion is either not known or not yet serious, a number of measures are taken in addition to the curative devices to check the inception of soil erosion. These other measures include limitation of the extent of forest degradation by evolving a system of cultivation which will always ensure that the ground surface is under effective vegetative cover; controlling the extent and timing of bush burning; adoption of contour ploughing; introduction of inter- and multiplecropping and effective use of cover crops; and zoning and controlling of pasture use. Most methods outlined have been employed to combat the soil erosion menace in various parts of the country, but there is little to show that these efforts have been successful. On the contrary, there is everything to show that they have failed - a situation which emphasizes the need to face this problem of soil conservation more seriously. One reason usually given for the failure of soil conservation efforts is that farmers do not co-operate in the attempts but are passive and apathetic to any plans aimed at combating soil erosion. They are accused of unwillingness "to adopt the procedures deemed necessary to heal the land". It is equally stated that: "attempts to enforce farming on the contour, using ridges for growing yam and cassava in place of the familiar heaps, were viewed with suspicion, if not hostility. New methods of utilizing the soil, involving systematic crop rotations the planting of cover crops, mulching, green manuring and the addition of chemical fertilizers were similarly rejected by the rural population at large, being strange and untested innovations and beyond the technical and financial means of the ordinary farmer" (Floyd 1969, p. 120). Without assessing the merits of these statements, it seems that the main reasons for the observed failures could be summarized under three broad headings: lack of communication between the government and the people; inadequate knowledge of the environment; and agricultural excesses of the farmers. The government or its representatives hardly ever elicit the confidence of the people in connection with their conservation efforts. Yet, we know that it is neither wise nor desirable to make plans for conserving the soil without fully involving those who are using, and who will continue to use the same soil. It should be realized that before any reasonable farmer could be attracted to change his methods of cultivation, he must first be convinced of the need to change and be satisfied that the new methods to be adopted would lead to better results - greater yields or higher income. In fact, these requirements and assurances have never been achieved by our erst-while soil conservation efforts.

Even more serious is the regrettable fact that soil conservation efforts have so far been based on inadequate environmental knowledge. It is clear that soil conservation measures have no Chance of succeeding when we are still ignorant of tropical soils, tropical agriculture and tropical forestry. For instance, what cover crops, shrubs and plants are best suited for effective conservation of our soils? It is lack of this vital knowledge that has led to the utilization of cashew trees as part of the soil conservation effort in the vicinity of Agulu-Nanka gullies (Anambra State) and elsewhere when it is clear that these trees are unsuitable for such purposes as they neither hold the soil in place nor encourage the thriving of undergrowth to form a protective soil cover. On the agricultural excesses of the farmers, mention should be made of indiscriminate bush cutting and burning, the usual practice of cultivating very close to existing gullies, and often on any slope, and uncontrolled movement of animals. There is an obvious need to tackle the problem of soil erosion in the country in a systematic, co-ordinated and sustained manner, based on an adequate knowledge of the environment. There is need for effective regulation to govern the conduct of human activities, especially in connection with agricultural practices. For example, there should be a limit to the extent and timing of bush burning which remains an important aspect of the agricultural practices of the people. Bush burning should be confined to the beginning of the dry season (or end of the rains). Such an activity in the middle of the dry season is both dangerous and destructive. In addition, it is important to restrict cultivation near gully edges. It is suggested that no cultivation should be allowed within a radius of 0.5 to 1 km from the edges of existing gullies in order to give soil conservation measures a chance to succeed. In the same way, free movement of animals has to be regulated so that pasturage does not disrupt what is expected to be gained through controlled cultivation. There remains, however, the question of foot-paths which are frequently used, mostly to fetch water from the gullies. The continued use of such foot-paths over steep slopes aids the expansion of the gullies. The alternative measure, which is strongly recommended, is to provide pipe-borne water for the people of the affected areas so as to minimize, if not completely halt, the frequent use of these slopes. Equally the movement of cattle herds should be controlled. Effort should be made to demarcate grazing grounds to avoid indiscriminate grazing at all times and in all places. Some form of schedule of use of the demarcated zones should be worked out in such a way as to avoid unnecessary hardship for the herdsmen and their herds, while ensuring maximum protection for the land.

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The Environmental Impact o f Urbanization The adverse effects of the failure of agricultural enterprise in the rural areas are increasingly being felt in the urban centres where the influx of people from the rural areas has led to congestion in residential areas and excessive pressure of population on the limited urban utilities. It is not surprising then that the urban environment has deteriorated in quality and the major cities are now faced with an environmental crisis engendered by destructive floods, poor sanitation and waste disposal systems, and the destruction or despoliation of open spaces. Moreover, the process of urbanization can be seen in the nearby landscape, where the city encroaches on rural land. Such urban establishments as housing, industrial estates, roads, hospitals, schools and recreational centres make considerable demands on rural land at the outskirts of the cities. Ibadan city has expanded in the last decade to engulf such villages as Apata, about 6 km on the Abeokuta road; Ojoo, 7 km on the Oyo road and Manatan, 4 km on the lwo road. Lagos has expanded beyond the island to engulf such mainland settlements as Mushin, Ikeja, Isolo and Agege. The metropolis now covers an area of some 289 km 2.

Competition for Land As a result of the competition for land on the outskirts of the cities many landowning families and local businessmen have become great land speculators and are operating in areas far beyond the present urban fringes. These land speculators sell to the highest bidder and are therefore largely promoting the interests of urban land uses which are more able to compete successfully against rural land uses. Indeed, nowadays, only such rural activities as poultry farming, intensive market gardening, sawmilling and earth material quarrying which cater to the needs of the urban centres survive in their vicinity. The situation on the Ikeja plains has been described previously (Areola and Faniran 1975, Areola 1976). The area is a low dissected but generally flat to gently-rolling terrain. The land is generally well-drained with deep, welldeveloped and comparatively fertile soils. The area is thought to provide Lagos State the best opportunities for arable farming and irrigation agriculture (Tahal ~974). However, the Ikeja plains also impose the least physical constraints on urban and industrial expansion of all the ecological land zones in the state. Thus the land is rapidly being taken up for urban uses.

Building Materials The boom in the construction industry, mainly in the urban centres, has created high demand for such building materials as sand, clay, gravel and "red earth". The quarrying of these materials is one of the major causes of forest

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clearance and land degradation in the rural hinterlands. Sand is dug both on land and in river channels. Faniran et al. (1976), have shown that river sand mining is carried out on gigantic scale along the creeks on the LagosIkorodu road. In a census survey carried out in 1975 they found that an average of 3661 tons of sand were loaded away per day from the creeks during the dry season when sand is generally more available. For a comparable period in the wet season the average tonnage of sand loaded away per day was 709. Altogether, sand is removed from the rivers and creeks on a very large scale throughout the year. In one respect river sand mining in these coastal rivers and creeks is quite benificial; it helps in maintaining these natural drainage lines so that they are not silted up. These rivers and creeks would be crucial in any ]and drainage and agricultural development projects that may be envisaged on the coastal swamps and river floodplains in the future (Tahal 1974). However, sand mining destroys the habitat of the freshwater fish. At the moment there is no apparent conflict between sand miners and the fishermen plying these waterways; indeed some fishermen are also part-time sand miners. The people obviously do not see any conflict between the two uses of the waterways. However, investigations by the Lagos State fisheries division have revealed that the fish population of these rivers have been adversely affected by sand mining. The quarrying of sand and other earth materials on land is widespread throughout the country. Because there has been a tendency to take these materials for granted, little attention has been given to their evaluation, exploitation or utilization. There are no laws or regulations whatsoever concerning the earth material quarrying activities, in contrast to regulations enacted for large-scale mineral operations. Thus the exploiter may dig anywhere he chooses as long as he has the consent of the land owner. In many rural areas and along the motorways, builders seldom bother to seek permission from the land owner. The quarrying of earth materials results in large-scale clearance of vegetation. For example, along with road construction, it has largely been responsible for the extensive clearance of land in recent years in the Lagos, Benin and Ondo forest regions. Entire interfluves or broad valley sides may be completely cleared and quarried. The exposed pits and earth dumps are often subjected to intense erosion by concentrated storm runoff. The exposed land surface soon hardens under the intense heat of the sun so that the reforestation of such lands is very slow. Near big towns and villages some of these pits have become the dumping ground for scrap metal and household refuse. Storm water runoff which collects in pools during the wet season often facilitates the breeding of mosquitoes.

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There are other environmental impacts of the quarrying of earth materials as exemplified by the Lagos coastal region. The fiat sandy plains running west of the metropolis below the Ikeja plains are extensively dug for both sand and clay wherever clay lenses occur within the sands. During the wet season the landscape is dotted with stagnant pools of water which have collected in the sand and clay pits. Apart from providing breeding sites for mosquitoes and other insects, the pits render many hectares of land waste. Yet the flat sandy plains are thought to have a high potential for the development of improved permanent pastures and dairy farming in this coastal region (Areola and Faniran 1975). The low dissected plateau hinterland of the Lagos State running from Agege in the west to Epe in the east is the zone of extensive gravel and red earth quarrying. This has rendered many hectares of land derelict and undermined the stability of slopes especially on the steep bluffs, marking the boundary of the plateau with the coastal plains. The most spectacular of the quarries was the one at Ojota above the Onigbongbo swamps on the LagosIkorodu road. About half of a ridge stretching more than 2 km was removed completely. The bottom of the pit is now some 5-10 m below the original land surface. However, because of the scarcity of land in this part of metropolitan Lagos the land has not been allowed to go to waste. Buldings are springing up inside the wide pit. But many less extensive pits are widespread throughout the low dissected plateau region which have left permanent scars on the land surface. Urban Floods The problem of urban floods arises from the spread of urban centres over the landscape in apparent disregard of the physical conditions of the terrain and the inadequacy of storm water control measures. Two contrasting urban landscapes may be considered: (1) the flat terrain with a high water table and numerous swamps that is characteristic of such coastal cities as Lagos and Warri; and (2) the hilly or strongly undulating and dissected terrain typified by Ibadan city. Lagos is located in an area of fiat relief which is almost at sea level. This fact coupled with the high water table, makes land drainage particularly difficult. The heavy torrential rains generate considerable runoff which does not move freely and quickly off the land surface because of the low relative relief. The capacity of the soil to absorb water is limited by a high groundwater level. Furthermore, many of the swamps around Lagos, which once served as natural reservoirs for excess water from the land surface and from overflowing rivers and creeks, have been filled in and the reclaimed land built upon. In such a physical environment,

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an elaborate system of storm water and flood control is called for. But, unfortunately many parts of the metropolis, even those areas as Surulere which were reclaimed from the swamps, have very poor drainage systems. The bank-full capacity of the drainage ditches and culverts is far too small to contain the runoff from heavy torrential rains of the wet season. Thus, almost every down-pour of rain results in floods. Drainage works in the Lagos area have always required huge sums of money. The funds have not often been readily available and this has been partly responsible for their poor quality. An indirect solution to the problem of scarce resources could have been achieved through a wise land use zoning policy. In metropolitan Lagos, there is the curious situation in which industrial estates are located on some of the best lands while residential areas are allocated more hazardous zones. The industrial areas of Ikeja and Isolo have not been as adversely affected by any of the recent urban floods as Surulere, a residential area. In most other parts of the world industrial establishments usually occupy lands that are more marginal than those for housing or agriculture. This is not only because of the relatively"dirty" nature of factories but also because industry can more readily afford the heavy capital expenditure on land improvement programmes than, say, housing or agriculture. Part of the reason for the present situation is, of course, that the industrial estates had to be so favourably sited in order to attract foreign industries to the country. There is need to reverse the trend and to make industries contribute directly to development of the lands they occupy. The 'oil city' of Warri faces the same problems as metropolitan Lagos. Like Lagos, it is located on a flat terrain which is generally less than 8 m a.s.l, while a large proportion of the area is actually less than 2.5 m a.s.l. There are numerous creeks and swamps. Warri experienced a sudden increase in population during the civil war when the prevailing circumstances forced the oil companies to shift their operations from the eastern to the western sector of the Niger Delta. The sudden increase in population was unexpected, creating serious accommodation problems. In order to meet the demand for housing, individual local entrepreneurs have established housing estates most of which, for want of space, are located in swampy areas or areas liable to flood. Such estates include Okumagba Layout, Essi Layout, Mosheshe, Idugbe and Odibo estates (Odemerho 1976). These local entrepreneurs have not been able to finance the elaborate flood control and storm water drainage works needed to make the land free of such environmental hazards. In fact, the flood hazards have increased in frequency since the urbanization of the terrain. By contrast, the ShelI-BP Senior Staff Quarters at Ogunmu, northwest of Warri, is among the best residential quarters in the town. Not only is the land better drained, but the

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company has been able to provide the necessary funds for its proper development. As in the case of metropolitan Lagos, again, it is ironical that the oil companies have been allocated the best and least costly to develop lands. Ibadan is a vast city sprawling over the undulating plains of the Ogunpa river basin and the adjacent quartzite hills and ridges. The appreciable relative relief, the fairly steep gradients, the numerous drainage lines and the generally light sandy loam to sandy clay loam soils, give the area high potential for runoff generation and sediment yield. The rapid expansion of the city over the years has greatly modified the natural landscape and vegetation cover. The intensity of soil erosion that can be generated by construction work on steep hillsides was recently attested to by the vast quantity of sediments that clogged the Ogunpa stream and spilled on to the Queen Elizabeth Road from the Premier Hotel Hill while the Cultural Centre was being built. In general there has been an increase in the frequency of floods in the city in the last two decades. The reasons for this are twofold: 1.

The amount of runoff from each heavy rain has been on the increase;

2.

The capacity of the streams to contain the flood flows has been decreasing.

The increasing amount of runoff may be attributed not only to the devegetation of steeply sloping land surfaces but also to the reduced ability of the soil to store water as a result of the sealing of many land surfaces by buildings and pavement. Even the infiltration capacities of open lands have been greatly reduced. For example, open spaces frequently trampled under foot, such as foot-paths and playgrounds, have been hardened and their infiltration capacity effectively reduced to zero (Akintola 1974).

The reasons for the reduced capacity of the streams to handle storm runoff are: 1.

The accumulation of solid wastes and debris increases the roughness of the channel and thereby reduces the hydraulic capacity. This also contributes to the occasional clogging of culverts and bridges;

.

The growth of grass and weeds in the channels also decreases the hydraulic capacity;

.

Some bridges and culverts built over the streams have insufficient hydraulic capacity; and

.

There has continued to be considerable construction of buildings within the flood plains (Maclaren International 1971 ).

Conclusion Throughout the rural and urban areas of Nigeria, man is confronted with serious environmental problems arising from the unplanned, unguided use of land and its resources and from poor management and destructive methods of agricultural production or natural resource extraction. It now appears that given traditional techniques of land resource management, the country has reached the limits of what it can safely eke out of nature without causing serious imbalances in the environmental system. It is obvious from recent experience that greater control and management of land use and natural resource extraction will not only be ecologically desirable, it will also be economically beneficial and profitable. Any plans to control land and resource utilization and to introduce new production and management techniques must be based on adequate scientific knowledge and technical data on the environmental factors which constitute the natural resource base of the country (Ofomata 1974, 1976a). The ways and means by which such data and information may be gathered and collated for planning purposes have been described in detail elsewhere (Areola 1974; Areola and Faniran 1977). The data and information thus collected would be needed not only in planning rural land use but also in overall regional planning (Bauer 1973). Thus far, most of the data collection has been undertaken at the reconnaissance level which means that the number of data points, and of the parameters measured and the mode and units of measurements are not quite adequate for detailed planning purposes. Except in a few instances the elements of the natural environments have been surveyed and studied separately in isolation from one another; the data from the various surveys have not been fully collated and synthesized whilst many have not been mapped, especially at the local level. The length of some of the records is still too short to provide a basis for analyzing temporal trends in the resource elements concerned. Much knowledge on the behaviour of resources under use (e.g. soil-crop relationships) is still largely restricted to research institutes. Efforts must now be made to transfer the results of research to the majority of resource users and developers. The problem with new innovations is the piecemeal fashion in which they have been introduced to the people. For example, chemical fertilizers have been indiscriminately distributed to farmers especially during the recent Operation Feed the Nation campaign. The total effect of such innovations on resource development has been very marglnal. The reason for their overall ineffectiveness is that the firm basis needed for their successful implementation does not exist. In conclusion, there is need for a comprehensive programme of natural resources conservation in Nigeria to

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provide a framework for land management and land control as suggested above. At the moment government efforts in this direction are restricted large!y to the forest and game reserves. There is need to inculcate land management ideas

and practices into routine land use activity. We must establish a conservation ethic in the country whereby every element of nature is seen to have value whether of an economic, cultural or aesthetic nature.

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