Environmental Laws in Nigeria and Occurrence of Some Geohazards : A Review

Nigeria as a country is blessed with an abundance of both human and natural resources. Exploitation of natural resources in Nigeria over the years with little or no regard for the environment has increased susceptibility of parts of the country to identified geohazards. A suite of environmental laws exist in Nigeria, all these aimed at protecting both the environment and its inhabitants. The aim of this paper is to review existing environmental laws in Nigeria, and occurrence of identified geohazards as a result of absence or non-implementation of these laws. Data for this study were obtained primarily from secondary sources. They are published government reports, journal articles, books, as well as other resources on the environment of Nigeria. Results show that Nigeria as a country has suitable existing and well-meaning environmental laws. The country also has many agencies charged with the responsibilities of implementing these environmental laws and policies. However, the non-implementation and nonexistence of identified environmental laws and policies has increased both exposure and vulnerability of parts of the country to geohazards. The effects of these include; loss of means of livelihood, environmental degradation leading to Badlands in parts of the country, as well as death in extreme cases. It is recommended in this paper that adherence to existing environmental laws Review Article Osumgborogwu and Chibo; AJEE, 2(4): 1-12, 2017; Article no.AJEE.34045 2 and policies as a panacea to mitigating identified geohzards is important. It is further recommended that amendment of already existing environmental laws to capture contemporary realities be made. This paper concluded by calling for more investment in the use of remote sensing and GIS tools such as LiDAR technology in the study of geohazards.


INTRODUCTION
It is often said that the environment can exist without humans but humans can barely exist without the environment.This has led governments all over the world to enact policies and laws aimed at protecting the environment and guaranteeing a sustainable environment for the unborn generations.Nigeria as a country is not left out in this case.A set of environmental laws and policies aimed at protecting the environment and its inhabitants exist in Nigeria.They include: the national policy on environment, the national forest policy, the national drought and desertification policy, national policy guidelines on solid waste management, national environmental (mining and processing of coal, ores and industrial minerals) regulations, and national environmental (soil erosion and flood control) regulations among others.These listed laws, regulations and policies are not exhaustive of all environmental statutes in Nigeria.The goal of these environmental policies is to ensure environmental protection and the conservation of natural resources for sustainable development [1].Despite this, Nigeria, battles a variety of environmental problems which constitute geohazards at different scales.They include; oil spill in the Niger Delta, gully erosion which supports landslides in the southern part of the country, incidence of flood in all states bothering major rivers (e.g., Niger and Benue) as well desert encroachment in the northern region of the country.With a variety of natural minerals, Nigeria is endowed with sufficient resources which could translate into wealth for the country.Sadly however, damage to the environment is usually seen as an unavoidable consequence of maintaining national development [2].This condition has led to near-total neglect of environmental laws in Nigeria at the pursuit of wealth and thus, many parts of the country bear the brunt of this neglect as evidenced in their susceptibility to a variety of geohazards.
By definition, geohazards are geological materials, features or processes that represent commercial and safety risks for development and for the environment, [3].They include earthquakes, tsunamis, landslides, gully erosion, flooding, fault rupture, turbidity currents, gas/fluid expulsion, over pressurised strata and adverse soil conditions.Geohazard triggering events may include seismicity, vulcanism, adverse weather conditions and human activities [3].Nigeria is susceptible to a number of geohazards such as flooding, gully erosion and gully-induced landslides and oil spill.The aim of this paper is to review existing environmental laws in Nigeria and occurrence of identified geohazards as a result of absence or non-implementation of these laws.The objectives include; identifying existing environmental laws, identifying their degrees of implementation and ascertaining susceptibility of parts of the country to identified geohazards as a result of non-implementation or non-existence of environmental laws and policies.This is important for it is likely that exposure and vulnerability to identified geohazards would be reduced were there implementation of stipulated laws and regulations protecting the environment and its inhabitants.

ENVIRONMENTAL POLICIES AND REGULATIONS IN NIGERIA
Environmental policies are those guidelines, laws, and regulations governing the relationship between humans and the environment.They range from policies regarding air and water management to issues concerning biodiversity as well as food production.A suite of environmental policy exists, all these are aimed at addressing environmental issues and the conservation of natural resources for sustainable development.[11] on hazardous usage of abandoned borrow pit sites in parts of Imo State, Nigeria, identified a myriad of human activities occurring within these sites.Some of these activities include construction of residential apartments, recreational and waste disposal activities.These human activities expose users and dwellers around pit sites to a variety of hazards such as flooding, soil subsidence due to adjustment, accelerated gully erosion and possible occurrence of landslide, ground water pollution and water poisoning.They concluded that absence of EMPs for road construction and other engineering projects, as well as borrow pit excavation encourages hazardous usage of abandoned borrow pit sites in the study area.In some parts of the world, certain criteria are set for borrow pit site selection and this is aimed at minimising adverse effects of borrow pits on both humans and the environment [12,13].In Nigeria, borrow pits are seen as derived demands because they supply needed laterite for road construction and other civil engineering projects.On completion of sand mining however, what becomes of the borrow pit sites?Some models have been suggested to ensure optimal pit reclamation at the end of mining activities.For example, spatial decision-support system (SDSS) [14], and the analytical hierarchy process (AHP) [2].These models were developed to mitigate possible impacts of open pit mining on the environment such as alteration of morphology, changes in hydrological pattern, loss of wild animal habitats, degradation of landscape value, reduction of property value, and loss of topsoil [14].But since there is no EMP currently guiding borrow pit excavation in many states of Nigeria, these models cannot be adopted and implemented thereby exposing abandoned pit sites to avoidable geohazards.iv.
National Environmental (Soil Erosion and Flood Control) Regulations, S. I. No. 12 of 2011; aimed at regulating all earth-disturbing activities, practices or developments for non-agricultural, commercial, industrial and residential purposes [4].Erosion is one of the geomorphologic processes that affect an area [15], yet, it becomes hazardous when it interacts with human activities in the affected places.Human activities such as deforestation, uncontrolled grazing, [16,17,18,19] as well as engineering constructions have accelerated rates of erosion, thus, increasing consequences on affected communities as well as the environment.Gully erosion is a major environmental problem in many parts of the country, with special emphasis on south east Nigeria.A combination of both natural and anthropogenic factors trigger this geohazard, for example fragile geological formation, high intense tropical rainstorm that lasts up to eight months in the year, long history of settlement, deforestation, geotechnical and hydrogeochemical characteristics as well as poor land use practices [20,21,22].Enforcement of this regulation will do little or nothing regarding natural causes of gully erosion, on the other hand, the human related factors could be properly managed to reduce environmental vulnerability to gully erosion.

GEOHAZARDS IN NIGERIA
Nigeria is susceptible to three geohazards; gully erosion and gully-induced landslides, flooding and oil spill and other environmental hazards such as desert encroachment.This paper reviews exposure and vulnerability of parts of Nigeria to these identified geohazards.a) Gully erosion and gully-induced landslides; gully erosion is a major geohazard in Nigeria, with special emphasis on southern Nigeria.Some landslide events occur as a result of extreme gullying, they are thus referred to as gully-induced landslides.They are often manifest in the form of slumping as a result of toe undercutting from gully erosion.Gully erosion has attracted the attention of researchers in Nigeria for many years.[23] adopted Geographic Information Systems (GIS) as a tool to identify and study gully erosion hazards in Abia State, southeastern Nigeria.They found that gully erosion sites were well dispersed around false bedded sandstone geological formation.Slope characteristics of gully sites were found to be greater than 15° which encourages erosion activities.
[24] used a community-based low-technology approach to study gully erosion in southeastern Nigeria.They established that many eroding gullies in the region were human-induced and preventable.Their results further revealed that many causes of gully erosion were traceable to poor land management practices and to a lack of innovation and awareness measures.They concluded that employment of communitybased, low-technology land management practices and public awareness programs through workshops, could halt the development of many gullies in the region.34].In Nigeria, it is said to affect and displace more people than any other disaster and also cause more damage to property [35].The damage caused by the 2012 flooding in Nigeria was unprecedented.Heavy rains between July and October 2012 combined with rising water levels resulting from the runoff contributed to the flooding of human settlements located downstream of the Kainji, Shiroro, and Jebba dams on the Niger River; the Lagdo dam in Cameroun on the Benue River; the Kiri dam on the Gongola River; and several other irrigation dams.In some cases, the dams were damaged; in others, water had to be released at full force to avert an overflow.363 people were killed, 5,851 injured, 3,891,314 affected, and 3, 871, 53 displaced due to the resulting floods [36], effects of the 2012 flooding in Nigeria are shown in Fig. 1 and Plates 2 and 3. Apart from the 2012 flooding event which has already been highlighted, other major flood events in Nigeria are presented in Table 1.
Extreme rainfall is a natural climatic factor capable of causing flooding, however, studies have also implicated human factors such as dumpsites within river channels and structural development within floodplains [35] as causes of flooding in Nigeria.c) Oil spill; the petroleum industry in Nigeria is the largest industry [37].It generates over 90 percent of the nation's foreign exchange earnings and over 80 percent of government annual revenue [38].Despite these, adverse effects of oil production in Nigeria are obvious in environmental, agricultural and health sectors.Published reports show that some activities associated with crude oil production with special emphasis on oil spill, can lead to environmental degradation, malnutrition in children and loss of livelihood [39,40].Oil spill as an environmental hazard is almost exclusively restricted to the oil producing Niger Delta region of Nigeria.Causes of oil spillage include sabotage, seismic activities, pipeline rupture, as well as landslides among others.In Nigeria, majority of oil spill cases are associated with sabotage, but it is also likely that landslide events initiated by extreme gully erosion could lead to pipeline rupture.Published studies have not identified this possibility in the study of oil spills but given the problem of extreme gully erosion and incidence of gully-induced landslides in some parts of Nigeria, it becomes likely that a scenario like this may occur.Due to the environmental degradation often associated with oil spillage, scientists have studied their effects on almost all branches of life.[41] adopted the twin tools of GIS and Remote Sensing in an assessment of the physical impact of oil spillage in Jesse Town of Delta State.They found that oil spillage was increasing unabated in the study area.With this increase in the occurrence of oil spillage comes a commensurate increase in the degradation of agricultural lands thereby turning hitherto productive areas into waste lands.[39] documented health hazards accruing from oil spillage.They found that oil spills could lead to a 60 percent reduction in household food security and were capable of reducing the ascorbic acid content of vegetables by as much as 36 percent and Plate 1. Severe gully site, Umueshi, Imo State, Nigeria

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hitherto productive areas into waste lands.documented health hazards accruing e.They found that oil spills could lead to a 60 percent reduction in food security and were capable of reducing the ascorbic acid content of vegetables by as much as 36 percent and the crude protein content of cassava by 40 percent.These they observed could result in a 24 percent increase in the prevalence of childhood malnutrition.The authors concluded that oil spills in the Niger delta region have acute and long-term effects on human health.

ENFORCEMENT OF ENVIRONMENTAL POLICIES AS A PANACEA TOWARDS PREVENTING AND MITIGATING GEOHAZARDS: NESREA
The dumping of toxic waste in Koko village of Delta State in 1987 reawakened the consciousness of the Nigerian Government to issues of environmental management.This event facilitated the establishment of the Federal Environmental Protection Agency (FEPA) in 1988.FEPA was charged with the overall responsibility for environmental management and protection.In 1999, FEPA and other related departments were merged to form the Federal Ministry of Environment.This new ministry did not have an appropriate enabling law on enforcement issues.This vacuum led to the establishment of The National Environmental Standards and Regulations Enforcement Agency (NESREA).NESREA, a parastatal of the Federal Ministry of Environment, was established in 2007 and is charged with the responsibility of protecting and developing the environment in Nigeria, as well as enforcing all environmental laws, regulations, standards, policies, guidelines and conventions on the environment to which Nigeria is a signatory.This agency has performed fairly well in few spheres, such as combating illegal importation and dumping of electrical/electronic waste (e-waste) in the country.However, more needs to be done in the aspect of preventing and mitigating geohazards associated with non-implementation of already existing environmental laws as identified in this paper.Occurrence of identified geohazards in Nigeria would have been limited if NESREA as an agency was fully equipped with appropriate tools and manpower to discharge its duties as required by law.NESREA could strengthen the National Environmental (Soil Erosion and Flood Control) Regulations, S. I. No. 12 of 2011 by suggesting farming methods to be adopted in states based on their distinct characteristics related to gully erosion.NESREA could enforce a regulation that mandates developers to allocate a specified percentage of land to fallow, this would reduce the volume of storm water (produced from built up areas and paved surfaces) capable of causing floods and initiating gullies.Introduction and implementation of these regulations are all aimed at checking flooding, accelerated erosion and their concomitant hazards.If NESREA had the wherewithal to sanction airing contractors who engage in unsustainable civil engineering projects, that could prevent their environmental unfriendly activities.This could mitigate the onset of fresh gullies while efforts are made to manage already existing gullies.As observed by [35], some causes of flooding in Nigeria include dumpsites within river channels and structural development 9 within floodplains.Again, in the implementation of the National Policy Guidelines on Solid Waste Management, NESREA could collaborate with state and local governments to ensure that management of one problem does not lead to the creation of another.Cases where municipal waste is either relocated from cities to borrow pits in the communities or simply dumped in waterways create more problems for Nigerians than they can solve.

RECOMMENDATIONS
Having reviewed on one hand existing environmental laws and regulations in Nigeria as well as their level of implementation, and exposure and vulnerability of parts of the country to identified geohazards on another hand, this paper makes the following recommendations.a) Assembling an expert Geohazard Assessment Team (GAT) in vulnerable states; this team will normally comprise experts from environmental management, geomorphology, geology, geophysics and geotechnics.This team would conduct research on the exposure and vulnerability of regions to geohazards such as flooding, extreme gullying and gully-induced landslides.The method developed by the GAT provides a framework for estimating; the frequency at which different geohazard events could be expected to cause loss to the environment; and − the level of financial loss associated with the different geohazard events [42].Further, magnitude and frequency of such geohazards are also documented by the GAT, this will give policy makers an idea of the nature of the problem the environment is exposed to.The use of Quantitative Risk Assessment (QRA) method is often adopted in assessment of geohazards such as landslides.Quantitative risk assessment involves estimating the probability of landslide events of different magnitude and their consequences [43,44].Such approaches could be adopted in assessing and communicating vulnerabilities of regions to gully-induced landslides.This will be a major way forward in preventing and controlling gully-induced landslides in parts of Nigeria.When this is implemented, it would almost eliminate the probability of oil spill occurrence in Nigeria as a result of landslide event.

CONCLUSION
This paper set out to review already existing environmental laws in Nigeria as well as susceptibility of parts of the country to identified geohazards as a result of non-implementation of these laws.A suite of environmental laws exist, parastatals within the ministry of environment also exist.However, parts of the country are exposed and vulnerable to identified geohazards such as gully erosion and gully-induced landslides, flooding and oil spills.Academics and researchers over the years have proffered solutions to these three identified problems, however, these hazards still constitute challenges to the inhabitants of the environment in Nigeria.Extreme gully erosion has attained a disaster level in southern Nigeria with some gullies growing to depths of 12m and lengths of more than 1.5 km long [26].The use of airbone LiDAR in gully erosion studies has been identified as one of the most promising data sources for studying gully systems because of its fine resolution and high accuracy [47].Airborne LiDAR has the ability to accurately represent gully cross-sectional form [48,49], to map the location of gully heads [50], and to characterize gully networks [51].Adoption of this technology as well as other remote sensing and GIS tools would lead to better management of gully erosion and gully-induced landslides.Use of modern technology in monitoring oil spillage in the oil producing environments of Nigeria will identify oil spillage as quickly as possible.This will reduce hazards associated with prolonged abandonment of spills on the environment which exposes the environment and its inhabitants to risks.Finally, implementation of the environmental management plans already discussed in this paper would reduce exposure and vulnerability of many regions of Nigeria to human causes of flooding.

COMPETING INTERESTS
Authors have declared that no competing interests exist.

Fig. 1 .
Fig. 1.Most affected states by the 2012 flooding in NigeriaSource[45] Regulations, S. I. No. 22 of 2011.Study has shown that absence of EMPs on waste disposal and management has led to the use of open pits as waste disposal centres in Nigeria [11].
iii.National Environmental (Mining and Processing of Coal, Ores and Industrial Minerals) Regulations, S. I. No. 31 of 2009; seeks to minimize pollution from mining and processing of coal, ores and industrial minerals and encourage the application of up-to-date efficient cleaner production technologies, [4].An aspect of this policy not fully appreciated is sand mining which leads to the excavation of borrow pits in various parts of the country.Study conducted by The authors added that 10 houses were lost in a single event of gully erosion in Auchi area of Edo State and over 450 buildings have been lost in Edo State of Nigeria as a result of severe gully erosion.They further reported that about 23 lives have been lost in the past few years in a single event of gullying activities in Ibori, Ugbalo, Ewu-Eguare, Idogalo and Oludide communities of Edo State, Nigeria.