EVALUATION OF FLOODING ON RESIDENTIAL BUILDING: A CASE STUDY OF KADUNA METROPOLIS

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 HISTORICAL BACKGROUND

 Flooding, for long has being one of the most common forms of natural disaster. It usually occurs when a river fills with water beyond its capacity. The surplus water overflows the banks and runs into adjoining low-lying lands. River floods are responsible for the loss of human life and the destruction of property. Each year, the number of deaths from flooding of rivers is more than any other natural disaster. The effects of natural hazards such as floods can be felt at local levels, affecting communities and neighborhood, or at regional or national levels, affecting entire drainage basins and large sparse of land between states (Kwak & Kondoh, 2008).

 In tropical regions, flooding of high magnitude that have resulted in serious consequences have been caused by heavy rain/thunderstorms, hurricanes, snow melt and dam failures (Jeb & Aggarwal, 2008).

 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.

This action leads to settling of the building i.e. sinking of the building which latter leads to cracking of the walls.

 Nigeria has recorded some of the highest death toll in the West African region, and in the northern parts of the country, where entire villages and huge sparse of agricultural land have been destroyed by flooding (African Research Bulletin, 2010).

 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 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).

 This research work focuses on flooding in Kaduna city, the capital of Kaduna State, Nigeria. Because the state has recorded series of flooding events in the past decades. The most recent flood was in September, 13th 2012 and it occurred after torrential rainfall that lasted for days causing at least 178 homes have been swept away in Kaduna metropolis following torrential rainfall. Flooding has destroyed infrastructures within Kaduna Metropolis and its surrounding farmlands. Over the years, the response of government and relief agencies to floods in Kaduna and other parts of the country has been in the area of rescue and supply of relief materials to victims of flood. Nothing has been done to ensure that the hazard is prevented and its associated risk is reduced to the barest minimum according to (Jeb & Aggarwal, 2008). Reduction of risk of flooding will depend largely on the amount of information on floods that is available and knowledge of the areas that are likely to be affected during a flooding event. Therefore, it is necessary to use modern day techniques in 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

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. Thus formulating and answering the following research question could define the overall purpose;

1. What are the residential hazards in a flooding prone zone?
2. What is the extent of damages caused by the flood in this flood prone zone?
3. What are the methods of reducing flooding on residential building?

 1.3 AIM AND OBJECTIVES

1.3.1 Aim:

The Aim of this study is to evaluate the effect of floods on Residential Building in Kaduna.

1.3.2    Objectives

1. To identify residential building hazard in a flooding prone zone
2. To determined the effect of flood on residential building in a flooding prone zone.
3. To determine the rate of damage caused by the flood to residential building.

 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 Kaduna 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 residential flooding in Kaduna metropolis of Kaduna state in Nigeria only. The research work would only be limited to data’s collected through questionnaire distributed to residents within Kaduna 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 Kaduna metropolis. Additional data will be gathered from SEMA and NEMA on the hazard caused by flooding in Kaduna metropolis, and all this will be analyzed using Relative Importance Index (RII).

 1.7 BACKGROUND OF THE STUDY AREA

Kaduna state is the successor to the old Northern Region of Nigeria, with its capital at Kaduna. In 27^th May 1967 it was split into six states, one of which was the North-Central State, whose name was changed to Kaduna State in 1976. This was further divided in 1987, losing the area now part of Katsina State. Under the governance of Kaduna is the ancient city of Zaria. Kaduna State occupies part of the Central position of the Northern part of Nigeria (with Kaduna as its capital) and shares common borders with Katsina, Zamfara, Kano, Niger, Bauchi and Plateau States. The State shares border with the Federal Capital Territory Abuja to the South-West.  The global location of the State is between longititude of 30^O east of the Greenwich meridian and latitude 0900 and 11 30⁰ North of the equator. The State occupies an area of approximately 48,473.2 square kilometers and has a population of more than 6 million according to (2006 census).

The entire land structure consists of an undulating Plateau with major rivers in the State including River Kaduna, River Wonderful in Kafanchan, River Kogom, River Gurara, Aso and Galma River. There are two marked seasons in the State, the Dry season and the Rainy (wet) Seasons. The wet season is usually from April through October with great variations as you move North-Wards.  On the average, the State enjoys a rainy season of about six (6) months. There is always heavy rainfall in the southern parts of the state like Kafanchan and northern parts like in Zaria with an average rainfall of about 1016mm. The State extends from the tropical grassland known as Guinea Savannah to the Sudan Savannah in the North.  The grassland is a vast region covering the Southern part of the State to about Latitude 1100’’ North of the equator.  The prevailing vegetation of tall grass and big trees are of economic importance during both the wet and dry season.