URBANIZATION EFFECTS ON WETLAND ECOSYSTEM IN PARTS OF NIGER STATE, NIGERIA

ABSTRACT

Wetland ecosystems provide multiple benefits to human settlements; nonetheless, they are seriously threatened due to lack of planning and human activities associated mainly with urban  growth.  An  understanding  of  their  functioning  and  status  is  crucial  for  their protection and conservation. The development and use of coastal areas have increased in recent  decades,  resulting in  significant  environmental  changes.  Thus,  these areas  have presented different population structures and growth patterns linked to global urbanization trends and demographic changes. The aim of this study is to compare wetland depletion and simulate future changes in parts of Niger State (Chanchaga-Minna, Landzun – Bida and Kontagora)  wetlands.  Four  multi-date  Landsat  satellite  imageries,  TM  of  1988,  1998, ETM+ 2008 and OLI 2018, were utilized to generate data and was used to analyze and monitor changes that have occurred over time and space. Land-use change modeller was utilized to model the land use and land cover and simulate future urban land use of wetland into 2030. The Normalized Difference Built-up Index (NDBI) was adopted to extract built- up  features  with  indices  ranging  from  -1  to  1.  Also,  simulation  was  performed  by integrating three drivers (DEM, distance to road and water). Questionnaires were used to examine the potential of effective land-use planning. The results of the classified Landsat images indicate that land use and cover distribution over Landzun – Bida exhibited more concentration  of  built-up  area  on  the  wetland  as  compared  to  Chanchaga-Minna  and Kontagora. At Landzun-Bida, the built-up areas occupied 12.35km2, while at Chanchaga – Minna, it occupied 8.2km2, and in Kontagora,  it is 7.8 km2  between 1988 and 2018.

Wetland depletion shows that 3.11km2 for Bida, 206.24 km2 for Minna, and 103.53 km2 for Kontagora are left in 2018, respectively. The simulated results on the wetlands indicate that Minna would have the largest built-up area of 1610.3538km² (42.91%), followed by Kontagora 801.1656 (Km2) 39.59% and Bida 25.6617 (Km2) (73.67%) in 2030. The implication is that wetland areas would decrease to 4.32km2 in Minna, 1.16km2 in Bida and 4.23km2 in Kontagora by the year 2030. It is paramount to note that human settlements are increasing   to   wetland   areas   across   the   study   locations.   The   conclusion   is   that spatiotemporal change in wetland land use and the land cover showed that the wetlands changed into different land use and land cover types due to population increase, farmland cultivation and increased built-up areas due to continuous urbanization. Therefore, it is recommended that human activities (both individuals and government) that degrade wetlands should be reduced, restricted or regulated. Also, the focus should be shifted from the immediate benefits derived from conversion to future and sustainable benefits derivable from proper wetland utilizations.

CHAPTER ONE

1.0       INTRODUCTION

1.1       Background to the Study

Wetlands are generally flat-floored, relatively shallow, and occupy the lower reaches of watersheds of large rivers, either located near the coast and generally do not have large flood plains (Windmeijer and Andriesse, 2013). They comprise valley bottoms and floodplains, which may be submerged for the greater part of the year? The hydromorphic fringes and contiguous upland slopes contribute water to the valley bottom through runoff and ground water flow. Wetland ecosystems, including rivers, lakes, floodplains and marshes,  provide  many  services  that  contribute  to  human  well-being  and  poverty alleviation (Millennium Ecosystem Assessment, 2015). However, they are increasingly subject  to  intense  pressure  from  multiple  human  activities  such  as  water  diversion, pollution, over-exploitation of natural resources, and reclamation.

As part of a natural ecosystem, wetlands, where they occur in the landscape, are valued for their contribution to ecological balance and biodiversity (Orji, 2014). Also, they are valued for  the  Numerous  goods  and  functions  delivered  freely  to  the  ecosystem  and  human habitats, including flood storage and distribution, retention of sediments and nutrients, aquifer recharge, Water quality improvement, aesthetic and educational benefits, among others (Kindsch er et al., 2015). Unrestrained degradation of wetlands and ecosystems lead to a loss or diminution of some or all of these functions. They also include human-made wetlands such as waste-water treatment ponds and reservoirs (Pepple, 2011). Urban populations and Wetlands have been engaged in a turbulent, somewhat symbiotic marriage since the dawn of civilization. Although wetlands are essential for human well-being, they have been progressively lost and degraded from human activities.

Humans have been using land and its resources for centuries in pursuit of their better lives. The way humans have used land and exploited its resources over time is a serious problem (Cieslewicz, 2002) as it has altered land cover and impacted the functioning of the ecosystem. With the advent of agriculture, modern technology, and the rise of the capitalist economy, the exploitation of land and its resources has increased dramatically. In the last few decades, land-use practices (agriculture, mining, logging, housing and recreation) have become  so  intensive  and  predominant  that  we  can  see  their  impacts  in  forms  of uncontrolled development (urbanization and sprawl), deteriorating environmental quality, loss of prime agricultural lands, destruction of wetlands, and loss of fish and wildlife habitats everywhere on the earth. Such impacts have reduced the local capacity of lands to support both ecosystem and human enterprise globally. Therefore, land-use change is no longer a local environmental problem but a global one (Houghton et al., 1994). To address such a problem on a global scale, detailed information on existing land use patterns and sound knowledge about changes in land use through time is  important for legislators, planners, and State and local government officials (Anderson, 1976).

Cities are growing faster worldwide, and there will be nearly 2 billion new city residents accounting for around 60 percent of the world‘s population by 2030, leading to severe damage of natural resources and ecosystems (The Nature Conservancy, 2008). When a city grows, it requires more land and resources to support the growth. This leads to change in land use causing environmental problems such as air and water pollution, loss of open space and biodiversity, heat island effects, etc. Furthermore, because the global human population is growing and rural to urban migration is increasing, the urbanization trend will continue at least for another few decades. This continuation of the urbanisation pattern will increase land and resource consumption and exacerbate the environmental problems which have already posed threats to our planet and cost billions of dollars to our economy. Therefore, planners, governments, planning agencies and others should acknowledge these problems immediately and put environmental perspective into land-use planning and decision-making process effectively and promptly.

Nigeria is  endowed  with  both  coastal  and  inland wetlands,  many of  which  are being threatened by anthropogenic drivers such as land use activities, urbanization, agricultural activities  in  addition  to  the  emerging  threats  of  climate  change  (Nwankwoala,  2012; Pepple, 2011; Kindscher et al., 2015; Orji, 2014). Minna, Bida and Kontagora cities, the Niger State economic nerve centres, are lying on a landscape endowed with wetlands and other ecological assets. With rapid urbanization and intense development pressure, some of the fringing wetlands and other land covers have been converted to urban and agricultural landscapes. The study seeks to establish that urbanization in the study area will result in an influx of people from rural areas to urban centers, resulting in the quest for more spaces to provide  accommodation  or  employment  for  the  ever-increasing  population. Moreover,lastly, draw attention tothe urgent need to protect and preserve wetlands in the study area. Based on the above background, the study will attempt to evaluate the effects of urbanisation on wetland depletion in Niger State and provide information that will aid policy makers in wetland management.

1.2       Statement of the Research Problem

Man‘s relationship with his environment has always changed with time, depending on his understanding and knowledge of the physical environment. However, the natural environment is endowed with a variable quantity of resources within the space. Thus, man has come to regard his environment as a way of housing his needs and therefore, he always seeks a way of extracting the resources within it. Sadly, however, this always leads to neglecting the environmental sustenance of several environmental stresses (Ezeaku et al., 2008; Jimoh et al., 2012).

Some parts of Chanchaga, Kontagora and Bida are situated on a wetland ecosystem. As a result of population growth, rural-urban migration, and the failure of successive governments to manage urban growth, these areas have expanded in an unplanned way, leading to the acquisition of more lands in the wetland area. As a result, these wetlands have suffered major encroachment in the recent past, especially in Bida and Chanchaga. A visit to the wetland reveals a lot of new activities, which signify recent massive encroachment. The activities include; residential and commercial buildings as well as car washing bays, among others. There is a significant reduction in the vegetation cover, and the wetlands now experience more visible instances of flooding than before during heavy rains. All these activities put much pressure on the wetland, affect its ecological function and cause degradation.

Niger State wetlands have been variously affected by conversion to developmental uses such as residential and commercial purposes.   This is seen in such areas as Chanchaga, Bida and Kontagora. Wetlands along The River Basin and Reclamation Road are mostly devastated and degraded by continuous sand filling and conversion for uses that bring economic activities as against the idea of conserving the wetlands. The institutional/legal frame works such as the Nigerian urban regional planning law as amended, Decree No. 18 of 1999, FEPA, Decree No.86 of 1992, EIA Act of 1992 and NESREA Act no.25, 2007 have not addressed the issue of urbanization and loss of wetland in the Niger state. None of the studies has provided the necessary information for urbanisation and loss of wetland in Niger State. Therefore, there is a need to close this yawning gap which forms the problem of this research. There is also a clear need for further research and improvement on this issue.

Several studies have been published on the effect of urbanization on wetland ecosystem management both locally and in other parts of the world, notable among them in recent times are; Ajibola et al. (2012), Pieter et al. (2013), Okonkwo et al. (2015), and Kometa et al, (2018). All these studies did not address the issue of urbanization and loss of wetland in the Niger State. None of the studies has provided the necessary information on the urbanisation effect and the resultant loss of wetland in Niger State. Therefore, there is a need to close this yawning gap which forms the problem of this research.

1.3       Aim and Objectives of the Study

The aim of this study is to evaluate the urbanization effect on the wetland ecosystem in parts of Niger State.

The objectives are to:

i.      examine spatial and temporal changes in the areal extent of the existing wetlands in the study area;

ii.      analyse the effect of human activities through urbanization on wetland ecosystem in the study area.

iii.      simulate the effects of urbanization on wetland ecosystem to the year 2030 in the study area.

iv.      examine the potential of land-use planning for an effective wetland ecosystem in the study area.

1.4       Research Questions

The following are the complimentary research questions:

i.      To what extent are different wetlands changing within the specified study period?

ii.       How does urbanization as a human activity affect the wetland ecosystem in the study areas?

iii.     What is the effect of urbanization on the wetland ecosystem in the year 2030?

iv.      What  are  the  prospects  of  land  use  planning  for  effective  wetland  ecosystem management in the study area?

1.5       Scope and limitations of the Study

The study examined the effect of urbanization on the resources of wetland ecosystem, soil, water and biodiversity along the flood plains of Rivers Chanchaga-Minna, Landzun-Bida and Kontagora in Niger State. The study utilized geospatial techniques, reconnaissance surveys  and  questionnaire  administration  to  assess  the  effect  of  Urbanization  on  the wetland ecosystem in parts of Niger State, Nigeria. In the course of the study, challenges such as difficulty of the terrain which was too marshy and flooded especially during raining season periods were encountered; especially during reconnaissance survey and Questionnaire administration. However, they were all over come and the study moved on smoothly to completion.

1.6       Justification for the Study

Many of the hydrological and water resources problems currently experienced in Nigeria are a result of wetland degradation. The challenges posed by the degradation can better be understood and better appreciated when viewed against the backdrop of the benefits derivable from the wetlands. UNEP (2013) alerts that globally, wetlands have been reduced by 50%. It is estimated that one-third of all endangered species are dependent on wetlands (Asibor, 2009). Nigeria is endowed with abundant surface and groundwater resources, but the water supply situation in the country for various uses remains far below expectation (Nwankwoala, 2011; Uluocha and Okeke, 2014). Aggravating the water management problem in the country is that wetlands, which naturally recharge and protect both the surface and groundwater resources, are being unscrupulously degraded at a rather alarming rate (Uluocha and Okeke, 2014).

Asibor (2009) identified fourteen (14) major wetland belts in Nigeria. However, despite many important wetlands in Nigeria, most of them are undergoing depletion due to population growth and urban land use (Chidi and Ominigbo, 2010). Because of these, the present study investigated the level of degradation of the wetland ecosystem and produced adaptive strategies to aid policy formulation on wetland ecosystem management both in Niger State and Nigeria at large.

1.7       Study Area

1.7.1    Location of the study area

Niger state is situated in the North-central Geo-political zone of Nigeria. It is located approximately between latitudes 8°20΄N and 11°30΄N, and longitude 3°30΄E and 7°20΄E (see Figure 1.1). The State is bordered to the North by Zamfara State, to the North-west by Kebbi State, to the South by Kogi State, to the South-west by Kwara State, while Kaduna State and the Federal Capital Territory border the state to the North-east and South-east respectively.  Furthermore,  the State shares  a common  international  boundary with  the Republic of Benin (Areola et al., 2014).

Source: Department of Geography, FUT Minna.

1.7.2    Size and population

Currently, Niger State covers a total land area of about 76,363 sq. km (about 9 percent of Nigeria’s total land area). This makes the state the largest in the country in terms of landmass. An estimated 80% of the state‘s land area is suitable for agriculture (i.e. arable). The 2006 official census result shows that Niger State has about 3,950,249, comprising 2,032,725 males and 1,917,524 females, representing the proportional share of 51.5% for males, 48.5%, respectively. The state accounts for about 2.82% of the country‘s population and ranks 18th. As opposed to a national population growth rate of 3.2%, Niger State has an annual growth rate of about 3.4%. (Daramola et al., 2019).

The state has about 26 identifiable native ethnic groups (the major ones being Nupe, Hausa and Gbagyi) and numerous non-native ethnic groups and languages. Administratively, the state comprises of twenty-five (25) local government areas grouped into three (3) agricultural zones which coincide with the senatorial divisions of the state; Zone I (made up of Agaie, Bida,Edati, Gbako, Mokwa,  Katcha, Lapai and Lavun LGAs), Zone II (made up of Bosso, Chanchaga, Gurara, Munya, Paikoro, Rafi, Shiroro, Suleja and Tafa LGAs) and Zone III (made up of Agwara, Borgu, Kontagora, Magama, Mariga, Mashegu, Rijau and Wushishi LGAs).

1.7.3    Climate

Niger State experiences a distinct dry season (from October – March) and a wet season (from April – October). Annual rainfall in the state varies from 1,200 mm in the northern part to 1,600 mm in the southern part. The length of the rainy season is 150 days in the Northern parts and210 days in the southern parts of Niger State. Mean maximum temperature remains high throughout the year, hovering about 32°C, particularly between March and June, while the minimum temperatures usually occur between December and January when most parts of the State come under the influence of the tropical continental air mass blows from the North-East (Harmattan). Generally, the state’s climate, soil, and hydrology permit the cultivation of most of Nigeria‘s staple crops and still allow sufficient opportunities for grazing, fresh water fishing, and forestry development (Daramola et al., 2019).

1.7.4 Geology

Niger State, like other states on the same latitude, is made up primarily of two major rock formations; the sedimentary and basement complex rocks. The sedimentary rocks dominate the southern part of the state and are characterized by sandstones and alluvial deposits, particularly along the Niger valley and in most parts of Borgu, Bida, Agaie, Lapai, Mokwa, Lavun, Edati, Gbako and Wushishi LGAs. This sub-area makes up the extensive flood plains of the River Niger. The basement complex rocks are found primarily in the northern and south-eastern parts of the state. These are mainly characterized by granitic outcrops or in selbergs found in the vast topography of the rolling landscape. Such inselbergs dominate the landscape in Rafi, Shiroro, Chanchaga, Mariga and Gurara LGAs (Nwajide, 2013; Daramola et al., 2019).

1.7.5    Soils and vegetation

Three major soil types can be found in the State. These include the ferruginous tropical soils, hydromorphic soils and ferrosols. The most predominant soil type is the ferruginous tropical soils, basically derived from the Basement Complex Rocks and old sedimentary rocks. Such ferruginous tropical soils are ideal for the cultivation of guinea corn, maize, millet and groundnut. Hydromorphic or waterlogged soils are largely found in the extensive flood plain of the Niger River. The soils are poorly drained and are generally greyish or sometimes whitish due to the high content of silt. Lastly, ferosols developed on sandstone formations and are characteristically red and enriched with a clay subsoil are found within the Niger trough. The Guinea Savannah vegetation covers the entire landscape of the state. Like in other states of similar vegetation, it is characterized by woodlands and tall grasses interspersed with tall, dense species. However, within the Niger trough and flood plains, taller trees and a few oil palm trees occur (Daramola, 2013).

1.7.6    Economy

Generally, agricultural activities form the mainstay of the people’s economy, as a large proportion of the population (about 85%) directly or indirectly engages in farming, fishing and cattle rearing. Major crops generally cultivated across the state include Oryza sativa (rice), Dioscoreasp (yam), Sorghum Vulgare (guinea corn), Zea mays (maize), Arachishypogaea (groundnut), Vignaunguiculata (cowpea or beans), Manihotesculentum (cassava), Saccharumofficinamum (sugar cane), Cucumismelo (melon or egusi), Voandzeiasubterrarean (Bambara groundnut), Glycine max (soy or soya bean), Ipomoea batatas  (sweet potato) and Pennisetum typhoides (millet). Other economic activities in the state (though limited in scale) include pockets of mining, banking, trading, food processing, manufacturing, transportation, local arts and crafts (Daramola et al., 2019).

Bida is a city found in Niger, Nigeria. It is located at 9.080 latitudes and 6.010  longitudes, situated at elevation 118 meters above sea level. Chanchaga is a Local Government Area in Niger State, Nigeria. Its headquarters is in the state capital of Minna, which occupies much of the Local Government Area. Its geographically located on latitude 9° 32′ 0″ North, 6° 35′ 0″ East while Kontagora is located in Nigeria located on the Coordinates: latitude 10°24′N and 5°28′E

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