CHALLENGES OF FLOODING IN PORT HARCOURT METROPOLIS AREA

CHALLENGES OF FLOODING IN PORT HARCOURT METROPOLIS AREA

ABSTRACT

Floods are water induced disaster that leads to temporary overflow of dry land and causes serious damages on lives, property, and infrastructures. However, flood hazard has cause a lot of worry in the country, causing the death of people, collapse of building, destruction of properties, agricultural produce, lost of land and increase government expenditure. The study discussed through evaluating the effect of flood on residential building, and samples were drawn to this effect, using descriptive sampling method, were a total number of 50 questionnaires were distributed with 40 retrieved from the respondents. Data collected from primary source consisting of a well structure questionnaire and conducting oral interview, while secondary data was obtained through literatures, text books, professional journal, reports and internet. The data was analyzed using significant index (S.I), relative important index (RII), percentage score, mean score, and standard deviation, in order to rank the factors causing flooding on residential building according to the degree  of significant as assessed by the respondents. The result obtained from ranking the factors reveals the first highest ranked three   major causes of flooding on residential building to poor drainage having RII of 4.70, second is heavy rainfall with RII of 4.60 and third is improper waste disposal with RII of 4.40. The study also ranked the possible ways flooding on residential building can be mitigated; the result reveals proper dumping of refuse with RII of 4.60, awareness of the public on the need to adhere environmental rules with RII of 4.45, empowerment of NEMA/SEMA to monitor residential building construction with RII of 4.43, implementation of government policies on flood with RII of 4.40 and town/city planners sanitization should be carried out with RII of 4.33 as the first five ways flooding on residential building can be mitigated. The statistical package for social scientist (SPSS) v19 was also used to analyze the variables using paired t-test and linear regression of 5% confidence limit. From the analyses, the findings shows property destroyed by the flood is worth more than 9 million naira. The study therefore recommends the government to take strategic approaches in mitigating flooding on residential building.

CHAPTER ONE

INTRODUCTION

1.1       Background Of The Study

Throughout history, water supply has been among the decisive factors in the search for adequate settlement locations. This has made river banks, coastal areas and lakesides to become preferred living spaces (WMO/GWP, 2008). Most cities, including Port-Harcourt are located in the valleys and flood plains or on coasts owing to their additional location advantages which favour development. Flood plains in the lower reaches of rivers provide fertile and flat land for productive agriculture. Moreover, estuaries and other coastal areas are more favoured as settlement locations since they may serve as linkages between river and sea navigation (WMO/GWP, 2008). However, one of the costs of such favourable locations is an increased flood risk. Irrespective of this, people continue to live in these areas.

A flood is the accumulation of too much water which rises to overflow land which is not normally submerged (Mukhopadhyay, 2010). Flooding can comprise overflow of a river as a result of prolonged seasonal rainfall, rainstorm, snowmelt, dam-breaks, accumulation of rainwater in low-lying areas with a high water table, or inadequate storm drainage. Floods could also be caused by intrusion of sea water onto coast lands during cyclonic/tidal surges (Handmer, Penning-Rowsell and Tapsell, 1999; Stoltman, Lidstone and DeChano, 2004). Floods have been noted to cause about one third of all deaths, one third of all injuries and one third of all damage from natural disasters (Askew, 1999). Flooding in various parts of Nigeria have forced thousands of people away from their homes, destroyed businesses, polluted water resources and increased the risk of diseases (Jeb and Aggarwal, 2008; Etuonovbe, 2011; Olorunfemi, 2011).

The occurrence of floods in Nigeria is not a recent phenomenon (Ayoade, 1979; Ayoade and Akintola, 1980; Olaniran, 1983; Ologunorisa and Terso, 2006; Adeloye and Rustum, 2011). The recent occurrences of flooding in Nigeria such as Sokoto flood in 2010, Ibadan flood in 2011, Lagos flood in 2011, and most parts of the country in 2012 had shown that flooding is one of the major environmental problems faced in Nigeria. Floods in Nigeria occur in three main forms, viz; coastal flooding, river flooding and urban flooding (Oriola, 1994; Okoduwa, 1999; Folorunsho and Awosika 2001; Ologunorisa, 2004; Orok, 2011). A review of these forms of floods have shown that, no single factor can be singled out as the only factor responsible for each flood type, though, a factor (e.g. rainfall) can cause all flood types. It has increasingly been acknowledged that the Niger Delta region in Nigeria experiences perennial floods owing to its location, low-lying topography and heavy rainfall, and Port Harcourt (located in the Niger Delta region) is one of such areas considered to be vulnerable to flooding. Some research works that examined the causal factors of flooding in Nigeria have attributed it to topography, soil/vegetation/river alteration, increased heavy rainfall, uncontrolled waste dumping, land use change and unplanned urbanisation (Oriola, 1994; Onokerhoraye, 1995; Parker, 1999; Folorunsho and Awosika 2001; Ologunorisa, 2004; Ogba and Utang, 2008; Adeloye and Rustum, 2011).

Flooding incidents have claimed many lives, rendered many others homeless and disrupted a wide range of environmental factors and socio-economic activities related to agriculture, vegetation and sustenance of human and wild life (Jeyaseelan, 1999).  Flood disaster is not a recent phenomenon in the country, and its destructive tendencies are sometimes enormous. The coastal cities of Lagos, Port Harcourt, Calabar, Uyo, Warri among others have severally experienced incidences that have claimed many lives and properties worth millions of dollar.  Floods occur in Nigeria in three main forms: coastal flooding, river flooding and urban flooding (Folorunsho & Awosika, 2001). Coastal flooding occurs in the low-lying belt of mangrove and fresh water swamps along the coast (Folorunsho & Awosika, 2001). River flooding occurs in the flood plains of the larger rivers, while sudden, short-lived flash floods are associated with rivers in the inland areas where sudden heavy rains can change them into destructive torrents within a short period (Folorunsho & Awosika, 2001). Urban flooding on the other hand occurs in towns, on flat or low-lying terrain especially where little or no provision has been made for surface drainage, or where existing drainage has been blocked with municipal waste, refuses and eroded soil sediments (Folorunsho & Awosika, 2001). Flood is very difficult to deal with; its devastating effects on buildings can be categorized into three: structural, economic, and health related effects. Disasters Management Centre, college of Engineering, University of Wisconsin – Madison (1995) identified the following structural effects of flood on buildings:

1. Buildings washed away due to the impact of the water under high stream velocity. Such buildings are usually destroyed or dislocated beyond feasible reconstruction
2. Floatation of buildings caused by rising water. This occurs when light–weight houses are not securely anchored or braced.
3. Damage caused by inundation of buildings: A building may remain intact and stable on its foundation, while its material is gradually and severely damaged.
4. Undercutting of building: here the velocity of flood may scour and erode the building’s foundation or the earth under the foundation. This may result in total collapse of affected buildings.
5. Damage caused by debris: massive floating objects like trees and materials from other collapsed house may have impact significant enough to cause damage to the standing buildings.
6. Flood leads to the exposure of some parts of the buildings foundation and soaking up of base blocks. The weakening of the base blocks by the flood may result to collapse
7. When the building foundation is not well rammed i.e. well compacted, excessive flood will lead to softening of the foundation base.

In recent times, floods have destroyed property worth millions of naira in the different areas of Nigeria. Flooding in urban areas is seriously becoming an ecological menace in Nigeria as several coastal areas along the Atlantic ocean, surrounding cities and river valleys are affected by flooding on a yearly basis (Jeb & Aggarwal, 2008) Floods have caused land degradation in some other parts of the country (Abbas, 2008). The obvious reason for flooding especially in municipalities and coastal areas in Nigeria like Porthacourt lies in the wide distribution of low-lying coastal areas and river floodplains, and because these areas have fast become an long standing attractions for human settlement (Ologunorisa & Abawua, 2005). It is against this background that this study seek to examine the challenges of flooding in Portharcourt metropolis area with the view of developing measures that will help government and relief agencies in identification of flood prone areas and in planning against flooding events in the future.

1.2       STATEMENT OF THE PROBLEM

The challenges and evaluation of floods will need knowledge of flood risk areas in order to develop prevention as well as mitigation measures in stopping it. Flood hazard has cause a lot of worry in the country, causing the death of people, collapse of buildings, destruction of properties and agricultural produce. So it is essential to define the actual causes of flood in order to minimize and avoid the occurrence of such hazard in the future.

Flooding is experienced in most homes during the rainy season, On a typical flooded day in the city, roads are rendered  impassable to both human and vehicular traffic, properties are damaged as a result of loss of value, and occupants are forced to vacate their homes and occasionally lives are made difficult for some times as a result of the economic effects of the loss, (Nasiri et al.; 2016). Furthermore, the effect of flood on the residents of the city of Port Harcourt especially property owners is such that many lives are lost and property worth millions damaged (Oku et al.; 2011). According to (Elenwo, 2015), the losses recorded as a result of flooding in the city are enormous; the destructions are complete or partial impairment of values on properties, goods and services. Flooding in the Metropolis was exacerbated by erection of illegal structures or buildings on water channels and the impacts on the environment especially on developed property values was the focus of this study. The following research questions were generated and answered in the study.

1. What are the frequency and duration of flooding in Port Harcourt Metropolis?
2. What types of drainage systems are available in Port Harcourt Metropolis?
3. What are the conditions of the drainages in Port Harcourt Metropolis?
4. What are the rent charges on developed property affected by flooding in the Metropolis?
5. What are the structural/erosional damage arising from the flooding and flood depth?
6. To what extent do frequency of flooding influence the value of developed properties in the Metropolis?
7. To what extent did drainage conditions, location of houses and rainfall intensities affect flood frequency?

 1.3      AIM AND OBJECTIVES

1.3.1    Aim:

The aim of this study is to examine the challenges of flooding in Port Harcourt metropolis area.

1.3.2    Objectives

The aim was achieved by the following identified objectives as follows to;

1.  Examine the frequency and duration of flooding in Port Harcourt Metropolis
2. Examine the availability of drainage in Port Harcourt Metropolis
3. Investigate the conditions of drainages in Port Harcourt Metropolis
4. Examine the rent charges on developed properties affected by flooding in the Metropolis
5. What are the structural/erosional damage arising from the flooding and flood depth?
6. Determine the relationship between frequency of flooding and the value of developed properties in the metropolis?
7. Determine the relationship between drainage conditions, location of houses and rainfall intensities

 1.4      Need For Study

Nigerian government established the National Emergency Management Agency (NEMA) through (Act 12 as amended by Act 50 of 1999), to manage and respond to disaster related activities in Nigeria such as flooding, accidents caused natural and man-made sources (Adeoye, 2009). NEMA is saddled with the responsibility of formulating policies, assessment of natural and man-made disasters, provision of mitigating measures for disaster related activities, coordinating plans and programmes for offering relief items to victims of such disasters. It is essential that assessment of floods will require knowledge of flood risk areas in order to develop prevention as well as mitigation measures in controlling flooding in the country. The Rivers State government established State Emergency Management Agency (SEMA) to also taken care of hazard area across the state.

1.5       Scope And Limitation Of The Study        

The scope of this research project is limited to challenges of flooding in Port Harcourt Metropolis Area. The research work would only be limited to data’s collected through questionnaire distributed to residents within Port metropolis.

1.6       Research Methodology

The research work is design base on relevant literature review carried out by academicians and professionals who have carried out series of researches on environmental disaster.

A convenient sampling method will be adopted; this is a sampling method according to (Teddlie & Yu, 2007) that involves choosing from a sample that is not only accessible, but respondent are willing to take part in the study.

Data for the research will be collected through a survey questionnaire administered to resident of Port Harcourt metropolis. Additional data will be gathered from SEMA and NEMA on the hazard caused by flooding in Port Harcourt metropolis, and all this will be analyzed using Relative Importance Index (RII).

 1.7      Background Of The Study Area

1.7.1 Location

Port Harcourt metropolis is located between Latitude 4045’N and Latitude 4055’N, and Longitude 6055’E and Longitude 7005’E. The city lies at the mouth of River Bonny in Rivers State. It is located at about 25km from the Atlantic Ocean and it is situated between the Dockyard creek/Bonny River and the Amadi creek. It lies at an average altitude of about 12m above mean sea level. Port Harcourt metropolis as our study area spans over two Local Government Areas (LGAs) viz; Port Harcourt and Obio/Akpor (Fig. 1) and was further divided into 13 Zones (Fig. 2).

1.2.2 Climate

The study area lies within the Koppen Tropical Rainy Af climatic zone of the Koppen classification (Koppen, 1936). Here, the average temperature for every month is above 180C and there is adequate moisture in virtually all the months. Port Harcourt metropolis experiences two seasons viz; dry and rainy seasons. Temperatures over Port Harcourt metropolis are constantly high with a mean maximum of about 340C and a mean minimum of about 210C. The highest temperatures are recorded between the months of April and October.