FLOOD GENERATING STRUCTURES IN KUBWA URBAN LANDSCAPE
This research work examined flood generating structures on Kubwa urban landscape Bwari Area Council. It is a combination of field observation through the distribution of questionnaire to the residents of the area and library research. Background for the study was discussed as well as problems were identified such as the causes and devastating effects of flooding in Kubwa which necessitated the need for this study. Research objectives were stated among which is to identify the flood generating structures and the areas vulnerable to flooding. Research questions and hypotheses were formulated to guide in achieving the objectives. The study reviewed both theoretical and related empirical literatures under headings such as the concept of flood, types of floods, effects of flood, pattern of floods among others. The study adopted the quasi-experimental research design which is a combination of both survey and field work. 170 respondents were selected using the stratified random sampling technique from each of the study areas; structured questionnaires were distributed to them. The researcher used both descriptive and inferential statistics to analyze the data obtained from the respondents and field work. The questionnaires were analyzed and presented in tables using frequency and simple percentages; while the data about the generating structures were analyzed using the standard multiple regression technique to estimate how the parameters (i.e. ponds, drainage, polythene, vegetation and house clustering) affect the rate of flooding. Some of the findings of the study revealed that the major cause of flooding in the area is rainfall and lack of sufficient drainage system, which occur mostly from July to September annually to high amount of rainfall within that period. The residents close to the drainage or blocked surfaces experience higher rate of destruction than those far away from the drainage. It was among other things recommended that there should also be regular and periodic sanitation exercise to clear refuse in drainages as this will go a long way in averting possible incidences of flooding; ponds should be well taken care to avoid escalation of floods in addition to construction of dry dams/levees for the purpose of flood control as well as flood-mapping of vulnerable areas as these will go a long way in reducing the incidence of flooding in the study area.
TABLE OF CONTENTS
Title page - - - - - - - - - - i
Declaration - - - - - - - - - - ii
Certification - - - - - - - - - iii
Dedication - - - - - - - - - - iv
Acknowledgement - - - - - - - - - v
Abstract - - - - - - - - - - vi
Table of Contents - - - - - - - - - vii
CHAPTER ONE: INTRODUCTION
1.1 Background to the Study - - - - - - - 1
1.2 Statement of Research Problem - - - - - 4
1.3 Aim and Objectives - - - - - - - 6
1.4 Research Questions - - - - - - - 6
1.5 Research Hypotheses - - - - - - - 6
1.6 Significance of the Study - - - - - - - 7
1.6 Scope and Limitations of the Study - - - - - 8
CHAPTER TWO: LITERATURE REVIEW
2.1 Introduction - - - - - - - - 9
2.2 Conceptual Framework - - - - - - - 11
2.3 Examples of Some Flood Events - - - - - 19
2.4 Flood Patterns - - - - - - - - 23
2.4.1 Normal Flood Pattern - - - - - - 23
2.4.2 Abnormal Flood Pattern - - - - - - 23
2.5 Flood Types - - - - - - - - - 23
2.5.1 Riverine Flood - - - - - - - 23
2.5.2 Coastal Flood - - - - - - - 24
2.5.3 Urban Flood - - - - - - - - 24
2.5.4 Flash Floods - - - - - - - - 26
2.5.5 Dam-Break Floods - - - - - - - 27
2.5.6 Groundwater Flooding - - - - - - 28
2.5.7 Sewage Flood - - - - - - - 30
2.5 Causes of Flood - - - - - - - - 31
2.5.1 Meteorological Processes - - - - - - 31
2.5.2 Geological Processes - - - - - - 31
2.5.3 Hydrological Factors - - - - - - 32
2.5.4 Anthropogenic Factors - - - - - - 37
2.6 Effects of Flood - - - - - - - - 38
2.6.1 Negative Effects - - - - - - - 39
2.6.2 Positive Effects of Flood - - - - - - 42
2.7 The Roles Geographical Information System (GIS) in
Environment Studies - - - - - - - 44
2.8 Empirical Review of Related Literature - - - - 47
CHAPTER THRE: RESEARCH METHODOLOGY
3.0 Introduction - - - - - - - - - 79
3.1 Area of the Study - - - - - - - - 79
3.1.1 Location - - - - - - - - 80
3.1.2 Climate - - - - - - - - 82
3.1.2 Soils - - - - - - - - - 82
3.1.3 Vegetation - - - - - - - - 83
3.1.4 Drainage - - - - - - - - 83
3.1.5 Settlement and Population - - - - - 84
3.2 Research Design - - - - - - - - 85
3.3 Population of the Study - - - - - - - 86
3.4 Sample Size and Sampling Technique - - - - - 86
3.5 Sources of Data Collection - - - - - - 87
3.6 Method of Gathering Data - - - - - - 89
3.7 Method Data Analysis - - - - - - - 89
CHAPTER FOUR: DATA PRESENTATION AND ANALYSIS
4.0 Introduction - - - - - - - - 91
4.1 Data Presentation - - - - - - - - 91
4.2 Data Analysis - - - - - - - - 93
4.3 Test of Hypothesis - - - - - - - - 104
4.4 Summary of Findings - - - - - - - 108
4.5 Discussion of Findings - - - - - - - 109
CHAPTER FIVE: SUMMARY, CONCLUSION AND RECOMMENDATIONS
5.1 Summary - - - - - - - - - 112
5.2 Conclusion - - - - - - - - - 113
5.3 Recommendations - - - - - - - 115
References - - - - - - - - - - 118
Appendix I - - - - - - - - - - 122
Appendix II - - - - - - - - - - 123
Appendix III - - - - - - - - - 126
LIST OF TABLES
Table 4.1: Sex Distribution of the Respondents - - - - 91
Table 4.2: Marital Status of the Respondent - - - - 92
Table 4.3: Age Range of the Respondents - - - - - 92
Table 4.4: Major Occupation of Respondents - - - - 93
Table 4.5: Table showing vulnerable areas - - - - - 94
Table 4.6: Generating Structures of Flooding in Kubwa - - - 95
Table 4.7: Amount of Rainfall between 2012 – 2014 - - - 97
Table 4.8: Duration of Flood in Kubwa - - - - - 98
Table 4.9: Magnitude of Flood between 2012 – 2014 - - - 99
Table 4.10: Houses Affected by Flood - - - - - 102
Table 4.11: Regression Coefficients - - - - - - 105
LIST OF PLATES
Plate 3.1: Map of Nigeria showing the FCT - - - - 81
Plate 3.2: Map of the FCT showing Kubwa - - - - 81
Plate 4.1: A drainage channel in phase 4; blocked by silt waste product 96
Plate 4.2: Fish ponds in phase 4 - - - - - - 96
Plate 4.3: Food crop cultivation in phase 4 - - - - 97
Plate 4.4: A river valley in phase 3 before flooding - - - 100
Plate 4.5: The floodplain in phase 3 during the flood - - - 100
Plate 4.6: Floods in old Maitama of Kubwa during the Rainy season 103
Plate 4.7: Floods on NYSC road during the rainy season - - 104
1.1 Background to the Study
The world at large has in the recent past developed great concern over environmental issues such as global warming and its effect; flood which constitute a great problem to man, is both human-induced (anthropogenic) and natural disasters. Global warming is as a result of human activities such as deforestation, the release of carbon monoxide into the atmosphere in various ways and thereby creating hole in the ozone layer. The Intergovernmental Panel for Climate Change (IPCC, 2007), fourth assessment report reveals that the frequency of heavy precipitation has increased over most land areas that appear to be consistent with the global warming phenomenon. The impact of global warming on specific regions of the world has been estimated and predicted that “heavy precipitation events which are very likely to increase in frequency will augment flood risk”. This means that floods will get more severe in areas that are already prone to such disaster. They also observed increase in atmospheric water vapour, extreme temperature and increase in intense tropical cyclones in some regions.
Natural and Anthropogenic disasters had from prehistoric periods had serious impact on man and his environment. Natural disasters and anthropogenic disasters could come in form of earthquakes, cyclones, volcanic eruptions, landslides and floods. Impact of disasters on men are exacerbated by a number of factors which include poor land use planning, population growth, environmental mismanagement, increasing levels of vulnerability, poor governance and climatic change.
The loss of human lies, loss of assets and rise in the cost of reconstruction efforts as a result of flooding has placed Disaster Risk Reduction (DRR) on the policy agenda of many countries especially those areas prone to flooding. The hope of realizing the International Strategy in Disaster Reduction (ISDR)’s aim in reducing disaster is to mobilize the governments of different countries, United Nations (UN) agencies, Non-Governmental Organizations (NGOs), multi and bilateral agencies, regional bodies, private sector and civil societies to unit efforts in building a resilient societies by developing a culture of prevention, preparedness against and managing disaster (UN-ISDR, 2003).
Floods accounted for about 30 percent of all the natural disasters and 40 percent of the fatalities (Schecham & Hewitt, 1969). Flood is the outcome of a rainfall events or cumulative effects of episodic events, that comes man-induced disaster because of violation of the sanctity of the hydrologic cycle through man’s quest to control nature,(Adefolalu, 2008). Flood incidents are becoming annual events in all parts of Nigeria with varying degrees of impacts on man and his environment. The yearly report in various parts of Nigeria has been that of flood causing destruction and the death of many people and rendering people homeless. The destructions of scores of houses and many social infrastructures such as schools, roads and bridges are n the increase. Human factors responsible for flood in many areas are the improper operation of water resources infrastructure such as dams, and reservoirs, which were constructed to contain water and provide means of livelihood in times of need. Such structures introduce elements of risk to people upstream and downstream. These risks include destruction of unique habitats and biodiversity therein. There is also the possibility of levee and drain breakage, improper refuse disposal habit and occupation of the floodplain and imperviousness caused by trampling, roads and bridges constructions.
The need to reduce the effects of flood hazards or disaster becomes very imperative because it is difficult to control basic atmospheric processes which produce floods. The first step attempt by man in the process flood disaster reduction is to identify the factors responsible for flood in any flood prone areas. The occurrence of flood in Kubwa satellite town of the Federal Capital Territory in 2012 is one of the most recent severe flood disasters in the Federal Capital Territory (FCT). There are no records of flood disaster reported in the Federal Capital Territory before 2012, which indicates that flooding in the area can be attributed to the influx of people into the FCT which led to the emergence of various human activities in the area in recent time. Hence there is need to examine the phenomenon and proffer solution.
1.2 Statement of Research Problem
Flood has been an old time disaster that had plagued man and his environment in the world at large. In the recent past, most parts of the states in Nigeria had witnessed flood especially during high rainfall frequency and intensity.
In the past four decades, economic losses due to natural hazards such as, floods disasters have increased in folds and have also resulted in major loss of human lives and livelihoods, the destruction of economic and social infrastructure, as well as environmental damages during this period (Munich Re, 2002). Recurring floods and other disasters have been identified as a serious threat to sustainable development. Floods cause about one third of all deaths, one third of all injuries and one third of all damage from natural disasters (Askew, 1999).
Nigeria has suffered immeasurable losses to flood disaster – ranging the Imo State flood of (1988, 1989) which left over 50 people dead, 10,000 rendered homeless, oil and power infrastructures submerged; Ilorin also suffered a heavy casualty following the 1988 flood which left over 100 villages destroyed, 10,000 families displayed, over 70 km of farmland and 440 hectares of sugarcane plantation destroyed (Akintola & Williams, 2006).
In 2012, Nigeria was hit by a large wave of flood which was probably the biggest and most deadly flood disaster in Nigeria’s history, which affected about 2/3 of the federation, leaving scores of people dead and properties worth billions destroyed, with Kubwa District in the FCT having more than a fair share of the disaster.
One important point to note about flooding in this part of the world is that they are mostly human induced as a result of some harmful environment practices such as dumping of refuse in drainages, building on water ways, failure to adhere to building regulations among others.
Despite the obvious adverse effects of flooding, little has been done to savage the situation or correct the abnormalities, and hence, flood continues to threaten Nigeria’s wellbeing as well as the lives and properties of the citizens.
In the past, many works have been done on assessment of flood vulnerability risk but majorities of this work do not provide a reasonable solution to this devastating disaster and also lack of proper techniques to assess the flood risk, this is a major gap which this research intends to fill.
It is in the light of the above problem, that the researcher embarked on this study to determine the flood generating structures in Kubwa Urban landscape as well as suggest mitigating measures to curb the menace of flooding.
1.3 Aim and Objectives
The general aim of this research work is to examine the flood generating structures in Kubwa urban landscape. The specific objectives are outlined thus:
i) To identify areas vulnerable to flooding in Kubwa
ii) Examine the urban structures responsible for flooding in Kubwa
iii) To determine the magnitude of flooding in Kubwa from 2012 – 2014.
iv) To examine the consequences of flood in Kubwa
1.4 Research Questions
The following questions are designed to guide the study:
i) What are the areas vulnerable to flooding in Kubwa?
ii) What are the urban structures responsible for flooding in Kubwa?
iii) What is the magnitude of flooding in Kubwa from 2012 – 2014?
iv) What are the consequences of flooding in Kubwa?
1.5 Research Hypotheses
The hypotheses formulated for this study are:
H01: Polythene deposit has not significant effect on flooding in Kubwa.
H02: Ponds do not have any significant impact on flooding in Kubwa.
H03: Drainage has not significant impact on flooding in Kubwa.
H04: Vegetation has not significantly affect flooding in Kubwa
H05: House clustering does not significantly impact flooding in Kubwa
These hypotheses will be tested using multiple Regression technique at the 5% (p<0.05) level of significance.
1.6 Significance of the Study
Flood in Kubwa area of the Federal Capital Territory is a recurrent phenomenon. It occurred in the year 2012 and 2013 when this research was in progress. Both floods resulted in loss of lives and destruction of properties.
The findings and recommendations of this research can be a very useful information to government agencies, corporate estate managers, individuals, flood disaster managers and other stakeholders in environmental management and monitoring in the research area and other parts of the world faced with the problem of flooding.
The outcome of the research could serve as a tool towards public awareness on the rate of loss of lives and properties, where the environmental hazards occur, barren land and the pre-disposing risk for proper environmental planning.