URBANIZATION  AND LOSS OF WETLAND IN PORT-HARCOURT METROPOLIS NIGERIA

ABSTRACT

Urban  development  in wetland  ecosystems for  human settlement,  agriculture  and  industrial development is one of the biggest threats to wetland conversion and management.  Prediction of future urban expansion is very usefulfor urban planners and environmental managers in rapidly growing cities.  This study  aims to examine urbanization and loss of wetland in Port-Harcourt metropolis,  using remote sensing techniques.  The study  analyzes  land use /land cover changes (LULC)   using landsat5  TM and landsat7 ETM  images of 1984,1999,  2003 and 2013.Through this study,  the pattern ofurban  expansion for the next 29 years has been studied and changes in the distant future  (30 years from  now) have also been predicted.  The satellite images covering the area were acquired and analyzed using ArcGISl0.0, ERDAS IMAGE 2014 and IDRIS! Selva.

A total area of 40066.59 hectares was delineated in the study  area which is identified as area with potential for  expansion.  After  processing  the imagery,  five land use/land  cover LULC classes where developed in ERDAS environment, such as salt water wetland, freshwater wetland, fallow land,  built-up areas and water bodies.  Accuracy assessment using kappa statistics shows that overall accuracy assessment as of 1984 was 90.00% (0.85 kappa coefif cient),  in 1999 it was

88.00% (0.8337 kappa coefif cient),  in 2003 it was 100% (1.0000 kappa statistics) and in 2013 it

was 100% (1.0000 kappa  coefif cient).  The study  concluded that there is need for  wise use of wetland resources and improvement ofinstitutional arrangement so that wetland policies can be fully integrated into the planning process across all disciplines.

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CHAPTER ONE

INTRODUCTION

1.1  Background to the Study

Wetlands  are defined  as  areas  of marsh,  fen,  peat  land  or water,  whether  natural  or artificial, permanent  or temporary, with water that is static or flowing, fresh, brackish  or salt, including areas of marine water the depth of which at low tide does not exceed six meters (RCS,

2007). In addition, they ‘may incorporate riparian and coastal zones adjacent to the wetlands, and islands or bodies of marine water deeper than six meters at low tide lying within the wetland (RCS, 2007). Wetland therefore is “an ecosystem that arises when inundation by water produces soils  dominated  by  anaerobic  processes,  which  in tum,  forces  the  biota,  particularly  rooted plants, to adapt to flooding” (Keddy, 2010). Wetland ecosystems are among the most important in the world, providing a diverse range of ecosystem services vital to human well-being (Barbier et  al.,   1997;  RCS,  2007).  They  gave  rise  to  the  first  modem  global  nature-  conservation convention  (Matthews,  1993) and remain the only single group of ecosystems  with their own International Convention (Turner et al. 2000; Ramsar, 2010).

Globally, wetlands are estimated to cover 5-10% of the earth’s terrestrial surface (Mitsch and Gosselink, 2007; RCS, 2007), some 1,280 million hectares, although,  it is believed that this is an underestimate  (MEA 2005).  Some estimates put the global loss of wetlands at about 50% (Barbier,  1994;  Rijsberman  and Silva,  2006;  ICSU et al.,  2008).  However,  this is speculative, being  based  on extrapolation  of wetland  loss during the twentieth  century  of some types  of wetland in the areas that have been best documented including North America, Europe, Australia and New Zealand (MEA, 2005). Primarily, the factor that distinguishes wetlands from other land forms  or other water bodies  is the characteristic  vegetation  that is adapted to its unique  soil conditions: wetland  ecosystems  consist primarily  of hydro soil, which supports  aquatic plants (Butlers et al, 2010; Ramsar, 2011).  The water found in wetlands can be salt water, fresh water, or brackish (Ramsar, 2011). Main wetland types include swamps, marshes, bog and fens (Keddy,

2011).  Wetlands can be considered the most biologically diverse of all ecosystems,  serving as a

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home to a wide range of plant and animal life (Ramsar, 2011 ).  Wetlands  occur naturally  on every continent  except Antarctica  (USEPA, 2011). They can also be constructed  artificially  as a water management  tool, which may play a role in the developing  field of water-sensitive  urban design. The largest wetlands  in the world  include  the Amazon  River basin  and the west  Siberian plain (Fraser and Keddy,  2005).  The Niger delta is a wetland of about 76,000sq km and has the largest mangrove  forest  in  Africa  (11,134  sq km)  and  the  third  largest  in  the  world  (Spalding  et al,

1997).

Wetland ecosystems are part of our natural wealth.  At a world wide scale, they provide us with  services  worth  trillions  of US  dollars  every  year-entirely   free  of charge-making   a vital contribution  to human  health  and well-being. With the global population  set to increase  to nine billion by 2050, increasing pressure  on water resources  and the threats posed by climate change, the  need  to  maximize  these  benefits  has  never  been  greater  or more  urgent  (Ramsar,  2011). Numerous  factors contributed  to the degradation  of natural wetlands  in Nigeria  especially  in the Niger Delta region.  The most important  among them were land demand by a large population,  a lack of understanding  of wetland  values, a misguided  policy, a lack of environmental  laws and regulations,   and  water  diversion  needed  because  of rapid  economic  growth  (Ohimain  et al.,

2002).

Urban   development   in   wetland   ecosystems   for   agriculture,   human   settlement   and industrial development  is one of the biggest  threats  to wetland  conservation  and management. Management  of urban  development  in wetland  ecosystem  aims to conserve  major  services  and restore  natural  resources   while  meeting  the  socio-economic,  political   and  cultural  needs  of current and future generation  (Brussard  et al.,  1998;  and Szaro et al.,  1999).  Urbanization  which is the conversion  of land  into uses  associated  with  growing  population  and  economy  has been recognized  as having  a world -wide trend. More than 50% of the world’s population  currently resides in urban settlements.  The shift to urban living is expected to continue at the rates of 1.6% per annum at a global scale. The highest urbanization  rates were expected in developing and least developed  countries  (UN-Habitat,  2010)  while  95%  of the  net  increase  in  global  population would be in cities of the developing world (Zhang et al.,  2008) of which Port Harcourt is one.  As

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part of this trend, the coastal zones are known to be home to nearly 75% of the global population

(Asangwe, 2006).

Urbanization  is a major cause of loss of coastal wetlands. Urbanization  impacts wetlands in numerous direct and indirect ways. For example, construction reportedly impacts wetlands by causing  direct habitat  loss,  suspended  solids  additions, hydrologic  changes  and altered  water quality.  Indirect impacts include changes in hydrology  and sedimentations  which substantially alter  wetlands.  It also  exerts  significant  influences  on the  structure  and  function  of coastal wetlands,  mainly  through  modifying  the  hydrological   and  sedimentation  regimes,  and  the dynamics of nutrients  and chemical pollutants  (Adedeji  et al.,  2010).  Natural  coastal wetlands are characterized by a hydrological regime comprising concentrated flow to estuarine and coastal areas during flood events,  and diffused  discharge  into groundwater  and waterways  during the non- flood periods.

There has been a renewed focus on the study of urban systems in the last few years,  as urbanization  remains  a major  development  challenge  exerting  awesome  pressure  on  social, economic and environmental  sustainability  (Pickett et al.,  2001 ).  Cohen (2004) is of the view that in developing  countries, urbanization  is associated with natural population  growth, rural• urban  migration,  convergence  in rural  and urban  lifestyles,  and  the  economic  and political processes  associated with globalization.  Though urban areas currently account for about 3% of the Earth’s surface, the ecological footprint associated with urban expansion has important environmental  consequences  especially  on wetland  ecosystems.  According  to  Ehrenfeld  and Schneider   (1991),   wetlands   commonly   occur   in   human-dominated    landscapes   such   as agricultural and urban regions. Studies have shown that negative effect  on wetland species and ecosystem  functioning  can be expected  in such areas due to human  activities  (Ehrenfeld, and Schneider,  1991; Morris,  1991 ).

In the past,  wetlands have been regarded  as “wasteland,  which harbor disease vectors

(Kenyan  Wetland  Forum,  2013).  This  has  led  to  large  scale  drainage  and  conversion  for alternative uses without regard to ecological  and socio-economic  values. Wetland ecosystem is among the most productive  ecosystems  due to their functions  and attributes  (Kenyan, wetland Forum, 2013). Humankind benefits from a multitude ofresources and processes that are supplied

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by wetland ecosystem. Collectively, these benefits are known as “ecosystem services and include products like clean drinking water and processes such as the decomposition  of wastes.  Scientists and environmentalists have discussed ecosystem services for decades; these services were popularized  and their  definitions  formalized  by  the  UNITED NATION 2005  MILLENNIUM ECOSYTEM ASSESSMENT  (MA.),   a  four-year  intensive  study  involving  more  than  1,300

Scientists World- Wide (M.A., 2005). They group ecosystem services into four broad categories. The  Millennium  Ecosystem  Assessment   (MA)  report  (2005),  define  ecosystem  services  as benefit  people  obtain  from  the  ecosystem  service  and  distinguishes  four  categories  of the ecosystem  services:  they are provisioning  service,  such as the production  of food and water; “product obtained from ecosystem” are sea food and game, crops, wild food and spices, minerals and  diatomite,  pharmaceuticals,  bio-chemicals   and  industrial  products,  energy,  hydropower, biomass fuels.  Regulating  service include the control of climate and disease,  “benefits obtained from the regulation of ecosystem processes such as carbon sequestration and climate regulation, waste decomposition  and detoxification, purification  of water and air,  crop pollination, pest and disease control;  supporting  as in nutrient  cycles  and seed dispersal  that are necessary  for the production   of all  other  ecosystem  services”,   such  as  nutrient  dispersal  and  cycling,   seed dispersal. Non-material  benefits people obtain from ecosystem services are spiritual enrichment, cognitive   development,   reflection,   recreation   and  aesthetic   experiences,   such  as  cultural, intellectual  and  spiritual  experiences  (including  ecotourism  and  scientific  discovery)  (M.A.,

2005).

Wetland ecosystems  are important natural habitat,  which must be conserved (Williams,

1990).   They are associated with a diverse and complex array of direct and indirect uses. Direct uses include the use of the wetland for water supply and harvesting of wetland products such as fish and plants resources, while indirect benefits are derived from environmental  functions such as  flood  water  retention,   ground  water  recharge/discharge,  nutrient  abatement  etc.   Human activities in the wetland themselves may be fairly related to alternations; they may also be caused by activities  in the wetland  watersheds  and predominantly  by agricultural  ones i.e.  crop and livestock’s production (Zalidis et al.,  1997). Changes in wetland area may significantly affect the ecosystem processes and services.  Concern about changes in the size and quality of many of the

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world’s wetlands ecosystem has been growing as more and more wetlands are being converted to agricultural or urban land use and by natural factors like drought (Ringrose et al.,  1988; Gerakis and Kalburtji,  1998, Chopra et al.,  2001).

Despite their high productivity  and provision  of many benefits, wetlands ecosystems are still facing serious threats. These include inadequate or inappropriate human activities within the catchments  and in the wetlands, lack of coordinated  and holistic policy  guideline,  as well as climate change. The threats have induced changes that eroded the ecological and socio-economic values and services derived from the wetland (Ramsar, 2011). There is therefore an urgent need to efficiently  manage  urban  development  in wetland  ecosystems  to mitigate  the  threats  and ensure ecological sustainability.

Remote Sensing (RS) and Geographic Information System (GIS) are now providing new tools for advanced ecosystem management. The collection of remotely sensed data facilitates the synoptic analyses of Earth – system function, patterning, and change at local, regional and global scales over time; such data also provide an important link between intensive, localized ecological research  and regional, national  and international  conservation  and management  of biological diversity (Wilkie and Finn,  1996).

Therefore,  an attempt  will be made  in this  study to map  out the  classes  of land use/land cover of Port-Harcourt metropolis between  1984 and 2013 with a view to detecting the land consumption rate and the changes that have taken place in these classes, particularly, in the built-up areas and wetlands so as to predict possible changes that will take place in these classes within a period of 29 years using Remote Sensing data.

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 generally 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  the  neglect  of the

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environmental  sustenance of a number of environmental  stresses (Ezeaku et al.,  2008;  Jimoh et al.,  2012).

The Port-Harcourt  metropolis  is partly  situated on a wetland  ecosystem. As a result of rapid population  growth,  urban migration and the failure of successive governments  to manage urban growth, the Port Harcourt metropolis has expanded in an unplanned way which has led to acquisition  of more  lands  in  the  wetland  area.  Port  Harcourt  wetland  has  suffered  major encroachment  in the recent past. 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  wetland  now  experiences  more  visible  instances  of flooding  than before  during heavy rains. All these activities put a lot of pressure  on the wetland, affect  its ecological function and cause degradation.  It is believed that these activities are a consequence of the increasing rate of development and urbanization  in the Port Harcourt Metropolis.  Though there is insufficient  data at the present to link urbanization  with encroachment  on wetland,  the size and biodiversity of unconverted portions of wetlands have drastically diminished, with some areas completely converted.  In 2000, it was noted that 13% of the wetlands in Port Harcourt was severely degraded and by 2010, only 3.3% was remaining; even this remnant was being degraded (Nwankwoala, 2012; Wizor, 2012).

This   uncontrolled   urban   expansion   in   an  unsystematic   manner   has   had   senous repercussions  on the environmental  quality of many parts of the metropolis. Brody et al.  (2007), submit that rising population density in coastal area is usually associated with greater amounts of impervious surfaces,  alteration of watershed, coupled with diminished capacity of these systems to naturally hold surface runoff. Studies suggest that, like in many coastal cities of the world, the precise impacts of these human activities  on coastal wetlands  are poorly understood  (James et al.,  2007).  In this case,  the precise nature of these changes is largely unknown  and unreported. Although Odunuga and Oyebande (2007), Taiwo and Areola (2009) have provided useful insight into  wetland  conversion  in  parts  of the  Lagos  coastal  area,  a  comprehensive   study  which assessed quantitatively  the spatial  changes  in the wetlands  of Lagos/Lekki  Lagoons  and their consequences is yet to be reported.

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Almost every type of wetland has been studied with satellite imagery.  But only few of these studies have been reported in a developing country like Nigeria (Campbell,  1996; Li et al.,

2005; Neale et al.,  2007;  Fabona et al.,  2007;  Jenson,  2007;  De rock et al.,  2008;  Taiwo et al.,

2009; Olaleye et al., 2009; Tijani et al., 2011; Klemas, 2011). In some studies, multi-temporal imageries often aided classification of wetlands as well as their separation from other land cover classes.  Included  in the types  of wetland  studied with remote  sensing  are marshes,  swamps, Lagoons,  coastal tidal marshes,  mangroves  and other coastal wetlands,  bogs and fens,  inland fresh  water  marshes,  forested  wetlands  or  swamps,  open  water  areas,  wet  meadows  and submerged aquatic vegetation (Obiefuna et al.,  2013).

Scientific  studies  fault the use  of natural  resource  management  rather  than managing whole ecosystem when dealing with a particular resource for human use (Kellert et al.,  2000). With the main objective  of sustainability  for future generations, ecosystems  manage  strive to balance natural resources exploitation and conservation over a long time (Ascher,  2001).  In the last  few  years,  there  has  been  an  unprecedented  rate  of urbanization  in  the  Port-Harcourt metropolis due to the closure of the Western Division of Shell Petroleum Development Company leading to the relocation  of their  oil facilities  to Port-Harcourt  and insurgency by the Boko Haram sect in the North.  The large influx of industries has led to urban growth and expansion into wetland because of need for land and new housing (Obinna, Owei and Mark, 2010).

Port Harcourt  which  is among the largest  cities  in Sub-Saharan  Africa,  is in fact the largest city in the Niger Delta Region.  The current demographical  estimate (NPC,  2006) of the population of the Port Harcourt urban area (urban agglomeration) is 1, 000, 908, covering an area of approximately 3 71 square kilometers for a density of 2695 per square km.  Indeed, the struggle for  land  has  led  to  massive  destruction  of wetland  ecosystem  for  developmental  purposes (Obinna, Owei and Mark, 2010). Wetland reclamation, Population increase, industrialization and urbanization  resulted  in an increased demand  for space for housing  and other infrastructure. Multinational companies, particularly those in the oil and gas industry,  also reclaim wetland for their use (Etuonovbe, 2007).

Port-Harcourt  wetlands  have been variously  affected  by conversion  to developmental uses  such  as  residential  and  commercial  purposes.   This  is  clearly  seen  in  such  areas  as

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Iwofe/UOE, Marine Base, Mgbuoba, Reclamation  Road, Rukpokwu, Choba, Rumuokwurushi, Eneka, GRA Phase 1-3, Eagles Island, Elioparanwo and Woji   etc. Wetlands along Marine Base and  Reclamation  Road  are mostly  devastated  and  degraded  by  continuous  sand  filling  and conversion  for uses that bring  economic  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 Port-Harcourt metropolis.  Hitherto,  none  of the  studies  has provided  the necessary  information  needed  for urbanization  and loss of wetland in Port Harcourt.  Therefore, there is 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.

1.3      Aim and Objectives of the Study

The aim of this study is to examine urbanization  and loss of wetland  in Port-Harcourt metropolis. This will be achieved through some objectives, namely to:

1.         Identify types, size and nature of wetland ecosystem in the Port-Harcourt metropolis.

2.       Identify  land use and land cover classes in the wetland  ecosystem  of the Port Harcourt metropolis.

3.        Identify the causes of land use and land cover changes  in the wetland  ecosystem of the

Port Harcourt Metropolis.

4.       Forecast the future pattern of land use and land cover change in the wetland ecosystem of the Port Harcourt metropolis.

1.4      THE STUDY AREA

1.4.1     Location

Geographically,  the Port-Harcourt  metropolis  is positioned  between  Latitudes 4 45 N, and 4 55 N and Longitudes 6 55 E and 7‘05′ E. Port-Harcourt metropolis is located at about 25 km from the Atlantic Ocean and it is situated between the Dockyard Creek/Bonny River and the Amadi  Creek  (Okoye,   1975;  Oyegun  and Adeyemo  et al.,   1999).    Port-Harcourt,  originally

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known,  as “Igwe-Ocha” was founded in 1913 by the British in an area traditionally inhabited by the  Ikwerres.  It  was  named  after  Lewis  Viscount  Harcourt,  the  then  Secretary  of State  of Colonies.  The main City of Port Harcourt is the Port-Harcourt  City Local Government Area.  It serves as the Headquarters of Rivers State (Alagoa and Derefaka,  et al.,  2002).  Today, the Port• Harcourt metropolis is made up of two Local Government Areas,  namely Port-Harcourt  L.G.A

and Obio-Akpor LGA (See Figs 1  and 2).

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