Project – The Impact of Poor Drainage Infrastructure on Urban Flooding: A Case Study of Selected Communities in Ikorodu, Lagos State.

CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

Urban flooding has become a major environmental and developmental challenge in many cities across the world, particularly in developing countries experiencing rapid urbanisation, population growth and inadequate infrastructure provision. It occurs when water accumulates in urban areas faster than the available natural and artificial drainage systems can discharge it. Heavy rainfall, blocked drainage channels, inadequate stormwater facilities, poor land-use planning and the expansion of buildings onto natural waterways can increase the likelihood and severity of flooding. Urban flooding can damage residential buildings, roads, public facilities and commercial properties while disrupting transportation, economic activities and the daily lives of residents. The United Nations Office for Disaster Risk Reduction (UNDRR, 2017) explains that disaster risk is influenced by the interaction of hazards, exposure and vulnerability, making infrastructure provision and preparedness important components of disaster risk reduction. Similarly, Nkwunonwo, Whitworth and Baily (2016), in their review of urban flood risk management in Lagos, identify inadequate drainage capacity, poor urban planning, blockage of drainage facilities and development on floodplains as important factors contributing to flooding in the Lagos region. These conditions demonstrate that urban flooding is not determined by rainfall alone but is also influenced by the ability of urban infrastructure to manage and convey stormwater effectively.

Drainage infrastructure is an essential component of urban development because it provides a channel through which rainwater and surface runoff are collected and conveyed away from residential areas, roads and other developed spaces. It includes roadside drains, underground drainage networks, culverts, stormwater channels, gutters, canals and other structures designed to regulate the movement of excess water. An effective drainage system should have adequate capacity, appropriate design, proper connections and regular maintenance to ensure that stormwater flows without obstruction. Where drainage infrastructure is poorly designed, undersized, damaged, incomplete or blocked by solid waste and sediments, water may accumulate on roads and residential properties, resulting in flooding. Adelekan (2010), in her study of vulnerable urban communities in Lagos, identifies inadequate infrastructure and the failure to expand and maintain stormwater drainage systems as factors contributing to increasing flood risks. Adeloye and Rustum (2011) similarly explain that inadequate storm drainage facilities and weak urban planning have contributed significantly to flooding in Lagos. This suggests that the condition and functionality of drainage infrastructure are important considerations in understanding the occurrence and severity of urban flooding.

The relationship between drainage infrastructure and urban flooding is particularly important in rapidly growing cities where the expansion of residential and commercial developments places additional pressure on existing drainage networks. As urban areas expand, natural surfaces such as vegetation, wetlands and open land are increasingly replaced by roads, concrete surfaces, rooftops and other impermeable materials. These surfaces reduce the amount of rainwater that can infiltrate into the soil and increase the volume of surface runoff that must be conveyed through drainage channels. When drainage facilities are inadequate to accommodate this increased runoff, water may overflow onto streets, compounds and buildings. Nkwunonwo et al. (2016) explain that urbanisation, increased impervious surfaces, land-use modification and inadequate drainage infrastructure contribute to flood risk in Lagos. Similarly, Adelekan (2010) observes that uncontrolled expansion of built-up areas without corresponding improvements in stormwater drainage increases the vulnerability of urban communities to flooding. Therefore, the provision of drainage infrastructure must correspond with the pace and pattern of urban development to reduce the accumulation of stormwater and minimise flood risks.

In Nigeria, urban flooding has become a recurring environmental problem affecting several cities and communities, particularly during periods of intense rainfall. The problem is often intensified by inadequate drainage networks, indiscriminate waste disposal, poor development control, encroachment on waterways and insufficient maintenance of existing drainage facilities. In many urban settlements, drainage channels are either absent, poorly constructed or unable to accommodate the volume of water generated during heavy rainfall. Some existing drains are also obstructed by plastic waste, sand, vegetation and other materials, reducing their ability to convey stormwater. Ajisegiri and Adebayo (2022), in their investigation of flooding in Ajegunle, Ikorodu, identified inadequate drainage and blockage of drainage channels as principal perceived causes of flooding in the community. Their findings also showed that flooding affected property, water sources, educational facilities and economic activities. These findings reflect the importance of functional drainage infrastructure in managing urban runoff and protecting communities from flood-related damage.

Lagos State provides an important context for examining the relationship between drainage infrastructure and urban flooding because of its high population density, rapid urban expansion, low-lying areas and extensive network of waterways. The increasing demand for residential accommodation and commercial space has encouraged development in several parts of the state, sometimes without corresponding improvements in drainage infrastructure and environmental management. In some locations, natural drainage routes and waterways have been altered, obstructed or encroached upon by buildings and other human activities. Adelekan (2010) explains that uncontrolled urban expansion, inadequate infrastructure and poor maintenance of existing drainage systems have contributed to flood vulnerability in Lagos. Atufu and Holt (2018), in their assessment of flooding in selected Lagos communities, including Ikorodu, also identify heavy rainfall, blocked or failed drainage systems and inadequate land-use planning as important contributors to flooding. Their findings show that flooding can result in displacement, property damage, health problems and disruption of movement. These conditions make the provision, maintenance and effective management of drainage infrastructure essential to sustainable urban development in Lagos State.

Ikorodu, one of the local government areas in Lagos State, has experienced considerable residential expansion and changes in land use associated with population growth and urban development. As communities expand, the demand for roads, housing, public facilities and drainage infrastructure also increases. However, the availability and condition of drainage facilities may differ from one community to another. Some residential areas may have inadequate drainage channels, while others may have existing drains that are poorly maintained, undersized or obstructed by refuse and sediments. Ajisegiri and Adebayo (2022), in their study of Ajegunle community in Ikorodu, found that inadequate drainage and blocked drainage channels were major perceived causes of flooding. More recently, Farinmade, Adeleke, Niyigena and Olabode (2026) examined drainage systems in selected informal settlements within Ikorodu and reported that drainage channels were scarce, poorly maintained and unevenly distributed, contributing to recurrent flooding and environmental degradation. These studies provide direct evidence that drainage infrastructure is an important issue in Ikorodu and justify further investigation into its influence on flooding across selected communities in the area.

Poor drainage infrastructure has consequences that extend beyond the temporary accumulation of water during rainfall. Recurrent flooding can damage houses, roads, shops, schools and other public facilities, destroy household belongings, disrupt commercial activities and restrict residents’ movement. Floodwater may also mix with refuse, sewage and other pollutants, thereby contaminating water sources and creating environmental and public health risks. In communities where drainage systems are inadequate, residents may experience repeated losses and incur additional expenses for repairs, temporary accommodation and the protection of their properties. Ajisegiri and Adebayo (2022) reported that flooding in Ajegunle, Ikorodu, was associated with property loss, pollution of water sources, damage to school infrastructure and disruption of economic activities. Atufu and Holt (2018) also identified displacement, property damage, movement difficulties and health-related problems among the impacts of flooding in Lagos communities, including Ikorodu. Consequently, examining the impact of poor drainage infrastructure on urban flooding is necessary for understanding the environmental, social and economic challenges facing residents and for identifying measures that can improve flood management in selected communities in Ikorodu.

1.2 Statement of the Problem

Urban flooding has become a recurring environmental challenge in several communities in Lagos State, particularly during periods of heavy rainfall. Although rainfall is a natural occurrence, its effects in urban settlements are often intensified by inadequate drainage infrastructure, poor maintenance of existing channels, indiscriminate waste disposal and uncontrolled development. Where drainage channels are absent, undersized or unable to convey stormwater effectively, excess water accumulates on roads, residential compounds and other developed areas. This situation can result in the flooding of houses, damage to public infrastructure, disruption of transportation and loss of property. Nkwunonwo et al. (2016) identify inadequate drainage facilities, blockage of drainage channels and poor urban planning as important contributors to flooding in Lagos. Similarly, Adelekan (2010) establishes that the failure to expand and maintain stormwater drainage infrastructure increases the vulnerability of urban communities. The problem, therefore, is that inadequate drainage infrastructure may prevent effective stormwater management and increase the occurrence and severity of flooding in selected communities in Ikorodu.

Another problem concerns the condition, capacity and maintenance of existing drainage facilities in residential communities. Some drainage channels may be poorly constructed, incomplete, shallow or too narrow to accommodate the volume of runoff generated during heavy rainfall. In other locations, existing channels may be obstructed by refuse, sand, vegetation and other materials, thereby restricting the free movement of water. These conditions reduce drainage efficiency and increase the possibility of water overflowing into residential and commercial areas. Ajisegiri and Adebayo (2022), in their study of Ajegunle community in Ikorodu, identified inadequate drainage and blocked drainage channels as the principal perceived causes of flooding. Farinmade et al. (2026) also reported that drainage channels in selected informal settlements within Ikorodu were scarce, poorly maintained and unevenly distributed. These findings raise concerns about the adequacy and functionality of drainage infrastructure in the area and the extent to which existing facilities can cope with stormwater generated during periods of rainfall.

The problem is further intensified by rapid urbanisation, unplanned residential development and human activities that interfere with natural water channels. As communities expand, buildings, roads and other impermeable surfaces replace natural surfaces that previously absorbed or slowed the movement of rainwater. In some locations, construction activities may encroach on waterways or obstruct natural drainage routes, while indiscriminate refuse disposal can reduce the carrying capacity of existing channels. These conditions increase surface runoff and place additional pressure on drainage infrastructure. Adeloye and Rustum (2011) identify urban expansion, development on floodplains, weak planning enforcement and inadequate storm drainage as major contributors to flooding in Lagos. Atufu and Holt (2018) similarly identify blocked drainage systems and inadequate land-use planning among the factors associated with flooding in Ikorodu and other selected Lagos communities. The problem is therefore not only the absence of drainage facilities but also the interaction between poor infrastructure, inadequate maintenance and development practices that obstruct the natural and artificial movement of stormwater.

Furthermore, recurrent flooding creates social, economic, environmental and public health difficulties for residents of affected communities. Floodwater can damage buildings and household property, interrupt commercial activities, contaminate water sources, damage roads and restrict access to schools, workplaces and health facilities. Although previous studies have documented flooding in Ikorodu, there is a need to examine the relationship between the condition of drainage infrastructure and the extent of flooding across selected communities, particularly in terms of drainage adequacy, maintenance, blockage and the consequences for residents. Ajisegiri and Adebayo (2022) documented the effects of flooding on property, school infrastructure, water sources and economic activities in Ajegunle, Ikorodu, while Farinmade et al. (2026) identified recurrent flooding, environmental degradation and public health risks associated with inadequate drainage systems in selected Ikorodu settlements. This study therefore seeks to investigate the impact of poor drainage infrastructure on urban flooding, using selected communities in Ikorodu, Lagos State, as a case study.

1.3 Aim and Objectives of the Study

The aim of this study is to examine the impact of poor drainage infrastructure on urban flooding in selected communities in Ikorodu, Lagos State.

The specific objectives are to:

1. Assess the condition and adequacy of drainage infrastructure in selected communities in Ikorodu, Lagos State.

2. Identify the major factors responsible for poor drainage infrastructure in the selected communities.

3. Examine the influence of poor drainage infrastructure on the frequency and severity of urban flooding in the selected communities.

4. Assess the environmental, social and economic effects of urban flooding on residents of the selected communities.

1.4 Research Questions

The following research questions will guide the study:

1. What is the condition and level of adequacy of drainage infrastructure in selected communities in Ikorodu, Lagos State?

2. What are the major factors responsible for poor drainage infrastructure in the selected communities?

3. How does poor drainage infrastructure influence the frequency and severity of urban flooding in the selected communities?

4. What are the environmental, social and economic effects of urban flooding on residents of the selected communities?

1.5 Research Hypothesis

The following null hypothesis will be tested in the study:

H₀: Poor drainage infrastructure has no significant influence on the occurrence and severity of urban flooding in selected communities in Ikorodu, Lagos State.

1.6 Significance of the Study

This study will be significant to residents, the Lagos State Government, local government authorities, urban planners, environmental management agencies, civil engineers, construction professionals, researchers and students. It will provide information on the condition of drainage infrastructure and its relationship with urban flooding in selected communities in Ikorodu.

Residents of the Selected Communities: The study will help residents understand how poor drainage infrastructure contributes to flooding and the environmental problems associated with it. It will also encourage community participation in maintaining drainage channels, preventing indiscriminate waste disposal and protecting natural waterways.

Lagos State Government: The findings will provide useful information to the state government on the drainage challenges affecting selected communities in Ikorodu. It may assist in identifying areas requiring drainage construction, rehabilitation, expansion and regular maintenance. The study may also support the development of policies and programmes aimed at reducing urban flooding.

Local Government Authorities: The study will help local government authorities understand the drainage and environmental management problems affecting their communities. It may encourage improved monitoring of drainage facilities, regular environmental sanitation and collaboration with residents to prevent drainage blockage.

Urban Planners: The study will provide useful information to urban planners on the importance of integrating effective drainage systems into residential layouts and urban development plans. It may encourage better land-use planning, development control and protection of natural waterways.

Environmental Management Agencies: The findings may assist environmental management agencies in identifying human activities that contribute to drainage obstruction and flooding. It may also support environmental awareness programmes and improved waste management practices.

Civil Engineers and Construction Professionals: The study will provide information on the importance of appropriate drainage design, construction standards, maintenance and infrastructure capacity in controlling stormwater. It may encourage professionals to consider the drainage requirements of rapidly expanding residential communities.

Public Health Authorities: The findings may help public health agencies understand the health risks associated with recurrent flooding, including contaminated water, poor sanitation and exposure to waterborne diseases. This may support preventive health education and environmental health interventions.

Students and Future Researchers: The study will serve as an academic reference for students and researchers in environmental management, urban and regional planning, geography, civil engineering, public administration and related disciplines. It may also provide a foundation for further research on urban flooding, drainage infrastructure and sustainable urban development.

1.7 Scope of the Study

The study focuses on the impact of poor drainage infrastructure on urban flooding in selected communities in Ikorodu, Lagos State.

Geographically, the research will be limited to selected communities within Ikorodu Local Government Area. The specific communities will be determined according to their relevance to the study and the availability of respondents and accessible drainage infrastructure.

In terms of content, the study will examine the condition, adequacy, functionality and maintenance of existing drainage facilities. It will also investigate factors responsible for poor drainage infrastructure, including inadequate construction, poor maintenance, indiscriminate waste disposal, drainage blockage, unplanned development and encroachment on natural waterways.

Furthermore, the study will examine the influence of poor drainage infrastructure on the frequency and severity of urban flooding and assess its environmental, social and economic effects on residents. The research will focus specifically on drainage infrastructure and urban flooding rather than all environmental problems affecting Ikorodu.

1.8 Limitations of the Study

The study may encounter certain limitations during the collection and analysis of data. One possible limitation is the difficulty of obtaining complete information on the design, construction and maintenance history of drainage facilities in the selected communities. Some relevant records may not be readily available from the responsible government agencies.

Another limitation may be the difficulty of accessing certain drainage channels, particularly those located in densely populated residential areas or obstructed by buildings and other structures. This may affect the extent of physical observation that can be conducted.

The study may also experience difficulties in obtaining accurate information from residents concerning the frequency and severity of previous flooding incidents. Some respondents may not remember the exact dates, duration or extent of earlier flood events.

Financial and time constraints may further limit the number of communities and drainage facilities that can be examined. Nevertheless, the researcher will make efforts to obtain relevant information through questionnaires, interviews and physical observation to ensure that the study achieves its objectives.

1.9 Operational Definition of Terms

Drainage Infrastructure: The physical facilities and structures designed to collect, channel and discharge excess surface water from residential, commercial and other developed areas. These include gutters, culverts, underground drains, canals and stormwater channels.

Poor Drainage Infrastructure: A situation in which drainage facilities are absent, inadequate, poorly designed, damaged, blocked or insufficiently maintained to convey stormwater effectively.

Urban Flooding: The accumulation or overflow of water in developed areas, such as roads, residential compounds and commercial locations, resulting from inadequate drainage, excessive surface runoff or other hydrological factors.

Drainage System: A network of natural and artificial channels designed to collect and convey excess water from a particular area.

Stormwater: Rainwater that flows over land surfaces instead of infiltrating into the soil.

Drainage Blockage: The obstruction of drainage channels by refuse, sand, sediments, vegetation, construction materials or other substances that restrict the movement of water.

Urbanisation: The process through which towns and cities expand as a result of population growth, migration, economic activities and physical development.

Flood Frequency: The number of times flooding occurs in a particular location within a specified period.

Flood Severity: The extent or intensity of flooding, which may be assessed through water depth, duration, affected land area and the level of damage caused.

Environmental Degradation: The deterioration of the natural environment through pollution, waste accumulation, destruction of natural waterways and other harmful human activities.

Selected Communities: The residential settlements within Ikorodu Local Government Area that will be chosen for investigation in this study.

1.10 Organisation of the Study

This study is organised into five chapters.

Chapter One presents the introduction, background to the study, statement of the problem, aim and objectives, research questions, research hypothesis, significance of the study, scope of the study, limitations of the study, operational definition of terms and organisation of the study.

Chapter Two reviews relevant literature relating to drainage infrastructure and urban flooding. It covers the conceptual review, theoretical framework, empirical review and research gap.

Chapter Three discusses the research methodology. It presents the research design, area of the study, population of the study, sample size and sampling techniques, sources of data, research instruments, validity and reliability of the instruments, methods of data collection and techniques of data analysis.

Chapter Four presents the data collected from the field, analyses the findings and discusses the results in relation to the research questions and hypothesis.

Chapter Five presents the summary of findings, conclusion and recommendations based on the results of the study.

Project – The Impact of Poor Drainage Infrastructure on Urban Flooding: A Case Study of Selected Communities in Ikorodu, Lagos State.