Flood-Generating Structures in Kubwa Urban Landscape
Chapter One
Aim and Objectives
The general aim of this research work is to examine the flood-generating structures in the Kubwa urban landscape. The specific objectives are outlined thus:
- To identify areas vulnerable to flooding in Kubwa
- Examine the urban structures responsible for flooding in Kubwa
- To determine the magnitude of flooding in Kubwa from 2012 – 2014.
- To examine the consequences of flood in Kubwa
CHAPTER TWO
LITERATURE REVIEW
Introduction
Flooding is the most common of all environmental hazards and it regularly claims over 20,000 lives per year and adversely affects around 75 million people world-wide (Smith, 1996). Across the globe, floods have posed tremendous danger to people’s lives and properties. Floods cause about one third of all deaths, one third of all injuries and one third of all damage from natural disasters (Askew, 1999). Apart from droughts, about 90% of damages relating to natural disasters are caused directly or indirectly by floods.
Apart from droughts, about 90% of damages relating to natural disasters are caused directly or indirectly by floods. Record shows that more than two hundred people have lost their lives to flooding while hundreds of thousands have been rendered homeless and properties worth billions of Naira have been destroyed as a result of devastating floods across the country (Abugu, 1988; Oluduro, 1988; Sunday Times, 1988; Fabowale, 1997; Opalana, 2005).
Flooding in various parts of Nigeria have forced thousands of people from their homes, destroyed businesses, polluted water resources and increased the risk of diseases (Baiye, 1988; Akinyemi, 1990; Nwaubani, 1991; Edward-Adebiyi, 1997). This is due to the fact that as urban population keeps on increasing, more and more people are living in flood prone areas, such as areas along river beds and floodplains, which consequently increase the damage and death toll (Adeoye et al, 2009).
They usually are caused by intense storms that produce more runoff than an area can store or a stream can carry within its normal channel. Rivers can also flood its surroundings when the dams fail, when ice or a landslide temporarily block the course of the river channel, or when snow melts rapidly. On larger streams, floods usually last from several hours to a few days. A series of storms might keep a river above flood stage (the water level at which a river overflows its banks) for several weeks.
Floods bring misery to affected people. They can cause loss of life and often cause a great disruption of daily life: water can come into people’s houses, drinking water and electricity supplies may break down, roads can be blocked, and people cannot go to work or to school (Adeoye et al, 2009). Floods generally cause enormous damages worldwide every year. This could be economic damages, damage to the natural environment and damage to national heritage sites. Although different parts of Nigeria is exposed to flood almost every year, the 2005 and 2011 floods break all records of the past. The 2011 flood devastated three north eastern states of Borno, Bauchi and Taraba, washing away over 4000 farms and destroying over 5000 houses (Timothy, 2011).
Conceptual Framework
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).
Flood can be defined as any relatively high water flow that overtops the natural or artificial banks in any portion of a river or stream, (Audu-Bida, 2008).
CHAPTER THREE
RESEARCH METHODOLOGY/AREA OF STUDY
Introduction
In every research, due consideration must be given on how data will be collected and analyzed and be presented in order to catch or capture the aim of the study. Great significance has been put into data collection, data analysis and presentation. These data were collected with objective and subjective reason and analyze with inductive and deductive reasoning. This will be discussed under headings like research design, population of the study, sample size and sampling technique, sources and method of data collection as well as method of data analysis.
Area of the Study
This study covers the entire Kubwa district which comprises of Kubwa village, Kubwa resettlement area, Gbazango village (west and its eastern layout), Byazhin, phase 2, site 1, phase 2, site 2, phase 3 and phase 4. Kubwa is located in Bwari Area Council and is located close to the pan handle of the Federal Capital Territory between latitude 7023’0”north of the equator and longitudes 9017’0” East of the Greenwich Meridian.
The study area lies in the river Gurara and river Kaduna river system within Bwari Area Council. The area has been examine to be a flood plain of river Gurara, most of the flood plain now is a terrace on which agricultural land, industrial site and residential areas are found. The river system does not pass through the residential and industrial but through agricultural land.
Location
It is located close to the pan handle of the Federal Capital Territory between latitude 7023’0”north of the equator and longitudes 9017’0” east with a vast land of 1100km. A vast area with scenic landscape and its striking features makes the council unique; it shares broader or boundaries with Tafa local government area of Niger state, Kagarko Local Government of Kaduna, Abuja Municipal Area Council (AMAC), Gwagwalada Area Council and Nassarawa State. This region covers about sixty percent of the North-Eastern pan handle and it is broken into two rather unequal party by river Usuma valley, the north and east escarpment is a rugged and hilly country, but has areas with plan terrain. The hills are rocky and they rise very steeply from those low-lying areas with many of the peaks that arise up to 760m above sea level while the lowest elevation is about 490m above sea level (Chup, 2006).
Population of the Study
The population of this study comprises of the residents of Kubwa Area Council which is made up of both planned and unplanned areas with a total population of about 30,000 residents. These residents shall constitute the respondents for the study.
CHAPTER FOUR
DATA PRESENTATION AND ANALYSIS
Introduction
The main purpose of this study has to do with examining the effect of flood occurrence and its impact in Kubwa, Bwari Area Council. To achieve this, ranges of data were collected from the field. This chapter therefore deals with the presentation and analysis of the collected data. This is organized and presented in tabular form, expressing the responses made to the various questions asked in the questionnaires and these are computed and quantified in percentage. For instance, change in population, as a result of population growth rate, the consequences of floods in the study area, major occupation of the people in the study area.
CHAPTER FIVE
SUMMARY, CONCLUSION AND RECOMMENDATIONS
Summary
Kubwa has been experiencing major flood disasters in recent times, especially in those areas associated with poor drainage system and or entire absence of drainage in unplanned areas. Kubwa is one of the main areas in Bwari that has been experiencing that natural disaster. Flood in Kubwa is an annual event which seems to be serious as a result of the nature of human activities; in particular environment the flood being an annual event in the area it occurs during the month with highest amount of rainfall August/September every year.
It was in this light that this research was embarked on to determine the flood generating structures in Kubwa and how they influence flooding. The researcher adopted the quasi-experimental approach for this study by obtaining qualitative information from the residents of the study area, and getting quantitative data by personal measurements of the parameters employed such as house clustering measured using the nearest neighour index, vegetation, length, depth and width of drainages, areas with ponds and level of refuse disposal.
Questionnaires were randomly distributed to the respondents; which were split evenly using the Stratified Random Sampling method to draw out the samples from the population; where a total of 25 respondents are drawn from each ward, and questionnaires are issued to them. A total of 5 questionnaires are distributed to each of the randomly selected streets in a ward.
The analysis was conducted using the ordinary least squares method of regression to estimate the effect of these variables on flooding, and the results presented in tables.
It was discovered among other things that polythene deposit and ponds significantly increase the level of flooding, while vegetation and house cluster, even though they increase flooding, are not statistically significant. However, it was discovered that drainage has a negative effect on flooding, as flooding reduces if drainage increases. It was learnt that 86.7% changes in flooding is caused the parameters employed in the study.
Conclusion
Flooding is a world-wide problem which, in many countries results in the loss of lives and extensive damage to infrastructure and agricultural production. This research has made efforts to interpret what causes the flooding in Kubwa area, the consequences of the floods and formally its control. Right from the previous chapters, we have seen that the flood is caused by two major factors namely: natural and anthropogenic factors (human induce activities). Floods of devastating dimensions impact adversely on the social and economic life of the people. Adequate measurements must therefore be taken always to avert or minimize the risk associated with its occurrences.
The natural factors involve high amount of rainfall, the poor soil infiltration (meteorological factors). The human factors (anthropogenic) include indiscriminate refuse dumping in water ways, lack of public education, inadequate drainage system, buildings and structures along water ways, poor urban planning and finally effort of man in clearing natural vegetation to modernize his environment. A natural phenomena life flood has been causing great damage to physical and human environment stagnate development and wellbeing of any environment and resulting in the loss of lives and properties.
Due to hazards associated with flood, there is a need to control this annual flooding in our environment in order to come up with safe environment. This could be achieved through public relief, abatement and control, land elevation, emergency action structural adjustment, land use regulation and flood insurance. In other words, flood as a natural phenomena cannot be completely stopped, rather there are some possible measures to control it and predict its consequences. The importance of properly organize drainage system cannot be over-emphasized as it would greatly improve our living condition and environment (Kolawole, 1987).
Recommendations
Based on the findings of this research, the following recommendations are hereby proffered:
- This study recommends the need for better and effective flood mitigation system in Kubwa and the whole of the FCT to ensure the safety of people and economy such as flood alert and early warning mechanism.
- Dry dams/levees should be constructed in addition to the Usuma dam for the purpose of flood control. Dry dams typically contain no gates or turbines, and are intended to allow the channel to flow freely during normal conditions. This will go a long way in reducing the incidence of flooding in the study area.
- To avert damages from flood disaster in the future, there is need to educate the people living on the flood plain who are vulnerable about the risk and hazard associated with continuous occupation of the area.
- 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.
- The Federal Capital Territory Authority (FCT) should create a system to convey and manage storm water in order to mitigate safety hazards and minimize property losses and disruptions due to heavy storm water run-off and flooding in Kubwa.
- Demolition of illegal structures: Structures that are built on the pathways of flood waters which their obstruct flow should be demolished. This would reduce the increased rate of uncontrolled urbanisation/urban creep and decongest Kubwa.
- Local preparedness to mitigate the negative effect of flooding: This requires sensitization of the communities on flood and flooding and most important of all, educate them on what to do in the event of flooding.
- Floodplain mapping:Scientist all over the world are of the view that the most effective way of reducing the risk of destruction of people and properties is through the production of flood risk maps. The essence of this is to delineate flood prone areas so as to avoid their occupation. This is the responsibility of Federal Ministry of Agriculture and Water Resources and Ministry of Environment.
- Evacuation and Resettlement:A non-structural but effective flood mitigation strategy is the evacuation and resettlement of riparian dwellers from flood plain areas to higher grounds. Their economic exploitation of the riparian zones can continue unhindered.
- Legislation: The relevant or appropriate arms of Federal Government of Nigeria and the Ministry of Federal Capital Territory (MFCT) will promulgate laws prohibiting occupation of flood plain areas.
- Flood Control Works: Essentially, and as conceived, flood control works involve the design and construction of diversion and protective structures such as dykes, levees, good drainage system and secondary reservoirs. A secondary reservoir will store excess flood water during period of abundance to be released later when flood level has subsided.
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