Investigation Into The Causes Of Blocked Drainage, Canal And Culvert In Ilorin-West Local Government Area

Drainage is an essential component of road construction. In most designs of the road, the first thing to be put in place is drainage system. The presence of blockage in drainage system tends to reduce the carriage capacity of drainage and thereby affect life span of the road.

Original price was: ₦ 3,000.00.Current price is: ₦ 2,999.00.



Drainage is an essential component of road construction. In most designs of the road, the first thing to be put in place is drainage system. The presence of blockage in drainage system tends to reduce the carriage capacity of drainage and thereby affect life span of the road. The research employed a research survey in order to obtain the information that would describe the causes of blocked drainage, canal and culvert in Ilorin-west local government road and its effect on the surrounding environment and the road users. Data collection techniques used includes questionnaires, photographs and observation.

The results show that Ilorin-west local government road drainage system was not adequate to satisfactorily drain the runoffs due to the blockage caused by debris, illegal dumping of refuse, Non-channelization e.t.c. As a result, the surrounding environment was greatly affected by washing away some sections of the road and bridges, creation of gullies on land, washing away of the fertility of the land.

The drainage facilities could be improved by frequent inspections, maintenance of gabions built for remedying of gullies and construction of water conservation structures e.g. water pans to hold and reduce the speed of water. Some drainage, canal and culvert system on Ilorin-west local government road should be redesign.


Title page                                                                                                                    i

Declaration                                                                                                                  ii

Certification                                                                                                                iii

Dedication                                                                                                                  iv

Acknowledgement                                                                                                      v

Abstract                                                                                                                      vii

Table of Contents                                                                                                       viii

List of Tables                                                                                                              xii

List of Figures                                                                                                             xiii

Appendix (List of plates)                                                                                            xiii


1.0       Introduction                                                                                                    1

2.0       Statement of the problem                                                                               3

3.0       Aim and objectives                                                                                         4

4.0       Justification                                                                                                     4

5.0       scope of the study                                                                                           5

6.0       Description of the project area                                                                        6

7.0       Research methodology                                                                                   6


2.0       Literature Review                                                                                           8

2.1       Introduction                                                                                                    8

2.2       Blockage Issues                                                                                              10

2.3       Types of Debris                                                                                               12


2.3.1   Overview                                                                                                         12

2.3.2    Floating Debris                                                                                               14

2.3.3    Non-Floating Debris                                                                                       15

2.3.4    Urban Debris                                                                                                   16

2.4       Types of Structures and Drainage Systems                                                    17

2.5       Causes of Blockage                                                                                        18

2.5.1    Overview                                                                                                        18

2.5.2    Modes of blockage                                                                                         19

2.6       Impacts of Blockage                                                                                       20

2.6.1    Overview                                                                                                        20

2.6.2    Hydraulic Impacts                                                                                          21

2.6.3    Economic Impacts                                                                                          22

2.6.4    Social Impacts                                                                                                 22

2.6.5    Environmental Impacts                                                                                   23

2.7       Effect of Blockage                                                                                         23

2.7.1    Overview                                                                                                        23

2.7.2    Consequences of blockages on flooding                                                        25

2.8       Control Measure                                                                                             26


3.0       Methodology                                                                                                  27

3.1       Introduction                                                                                                    27

3.2       Research Design                                                                                             27

3.2.1    Population                                                                                                       30

3.3       Data Collection Procedures                                                                            30

3.3.1    Data collection instructions                                                                            30

3.3.2    Primary data                                                                                                    31

3.3.3    Secondary data                                                                                               33

3.4       Data Analysis and Presentation Techniques                                                   33


4.0       Data Presentation and Analysis of Result                                                      35

4.1       Introduction                                                                                                    35

4.2       Results from Questionnaire                                                                            35

4.2.1    Results from Questionnaire Type One                                                            36

4.2.2    Results from Questionnaire Type Two                                                           36

4.3       Possible Causes of the Blockage                                                                    42

4.4       Results on Control of Blocked Drainage, Canal and

Study Area                                                                                                      44


5.0       Conclusions and Recommendation                                                                46

5.1       Conclusion                                                                                                      46

5.2       Recommendation                                                                                            47

Reference                                                                                                        50


Table                                                    Title                                                          Page

4.1       Response rate in rate in Agbo-Oba, Oja-Tuntun and Sawmill                       35

4.2       Number of years spent by the respondent rate in

Agbo-Oba, Oja-Tuntun and Sawmill                                                              39

4.3       Possible causes of the blockage in Agbo-Oba, Oja-Tuntun

and Sawmill                                                                                                    42

4.4       Control of blocked drainage, canal and culvert                                              44


Figure                                                     Title                                                        Page

4.1       Consideration for hydraulic design                                                               36

4.2       Years spent by the respondent                                                                        40

4.3       Frequency of road usage by road users                                                         41

4.4       The possible cause of the blockage                                                                43

4.5       Control measure in Agbo-Oba, Oja-Tuntun and Sawmill                             45


Plate                                            Title                                                        Page

1.0    Drainage blockage along Agbo-Oba road                                             54

2.0    Drainage blockage along Sawmill road                                                 56

3.0    Drainage blockage along Oja-Tuntun, kuntu area                                 57


1.0                  INTRODUCTION

            Nigeria is the most populous country in Africa. At the census of November 1991, Nigeria had 88, 514,501 with an inhabitants and a population density of 95.8 per 59 km.

The average annual growth rate between 1963 and 1991 is 1.7% (Baiye E; 1991). According to 2006 census figure, Nigeria had a population of 140 million people. The major hazard experienced in Nigeria includes flooding, erosion, deforestation, land degradation and climatic drought.

Flooding in Kwara state has been due to natural or artificial occurrences of blocked drainage, canal and culvert due to solid waste, wash away of the top soil, debris like trees, and leaves present in the water channel. Flooding has been experienced in different part of the state especially in Ilorin west local government area of the state, which has claimed life, damaged properties of the people that reside in the geographical area and as well as damaged the road pavement to greater extent.

Drainage is the process of removal of surface or subsurface face by water from a given area by natural or artificial means. (Adeyemi, 2005). The term is commonly applied to the removal of excess water by canals, drains, ditches, culverts and other structure designed to collect and transport water earlier by gravity or by pumping. A drainage project may involve large scale reclamation and protection of marshes, underwater lands or lands subject to frequent flooding (Microsoft- Encarta 2009).

Canal is an artificial waterway for navigation and irrigation, etc. it is a long narrow arm of the water penetrating an inland. Canals are man-made channel for water conveyance (Supply), or to services water transport vehicles. A true canal is a channel that cuts across drainage, making a navigable channel connecting two different drainage basins. Most commercially important canal of the first half of the 19th century were a little of each using rivers in long stretches and divide crossing canal in others. This is true for many canals still in use (Donald Lang mead, 2013).

A culvert is a conduit used as an artificial channel under a road way or embankment to maintain flow from natural channel or drainage ditch (Oshunkey, F.E (1992). A properly design culvert will carry the flow without causing damaging, backwater, excessive construction or excessive outlet velocities. Culverts usually have span less than 6m per cell (\www., (Albert transportation (2004)).

Blocked drainage, canal and culvert are caused as a result of high population of people living in a geographical area without the proper management of waste disposal, falling trees. Virtually every Nigerian is vulnerable to flooding either by natural or artificial.


            Ilorin-west local government area has been experiencing severe blocked drainage, canals and culvert over the years, which has makes life very hard for the residential in the area and result to loss of life and property.

It has rendered some people homeless and jobless; it is dangerous for the possibilities of infliction by diseases such as cholera, typhoid, fever, malaria etc. as a result of enhancing stagnant water. It also forces many occupants to relocate due to air pollution and others factor causes by blocked drainages, canal and culverts


            The aim of this project work is to investigate into the causes of blocked drainage, canal and culvert in Ilorin-west local government area of Kwara state in Nigeria.


  1. To look into the factor that causes blocked drainage canal and culvert.
  2. To find out the hazards which blocked drainage canal and culvert causes to human environment.
  3. To find out the various control measures needed to bring blocked drainage under control.
  4. To suggest a proper drainage, canal and culvert management.


            The construction of drainage, canal and culvert in the country is given much of structural or engineering consideration with little or no environmental impact assessment of the operations after the design and construction. The environmental problem results from operation which are usually devastating.

Hence, this study significantly addresses the following issues.

  • Identify the environmental hazards associated with the drainage, canal and culvert.
  • Evaluate the magnitude or significance of the hazard and effect.
  • Identify changes in downstream hydrology.
  • Identify changes in downstream morphology caused by altering the flow pattern.
  • Examine control techniques to eliminates or lesson the severity of the effect and to manage the hazards.
  • Develops plan and procedures to manage the environmental changes due to the operation of the drainage, canal and culvert.


            This project focus on the investigation into the causes of blocked drainage, canal and culvert; its effect and the possible control measure within Ilorin-west local government area in Ilorin.

The investigation covered the basic hazard which may be caused by blocked drainage, canal and culvert to the human environment and to look into the causes in the place it happens within Ilorin-west local government. Investigating the various control measure needed to bring blocked drainage, canal and culvert under control. 


            Ilorin west is one of the sixteen (16) local government in Kwara state and also one of the five (5) local government that made up Kwara central popularly known as (Emirate) with its headquarters located/ situated in Wara Osin in Ilorin metropolis, this capital of Kwara state. A case study of Agbo-oba, oja-tuntun and Sawmill was assigned.


            The methodology employed are:- preliminary data source, which may include:-


This is the feasibility study of the area to determine the Feeder Rivers, geology of the area and level of deterioration of building causes by flood as a result of blocked drainage, canal and culvert and also investigation into the cause of the blockage and also know the control measure to be used or adopted.


Oral interview was conducted to hear the view of the residents on the causes of blocked drainage, canal and culvert and to determine the control measure of the blocked drainage, canal and culvert in other to suggest the best control measures.


Questionnaires was distributed for analysis     


2.0      LITERATURE REVIEW       


Flooding is one of the most costly of natural disasters in Nigeria, as our population growth continues, and as we in turn urbanize and modify catchments, we have a need to create engineering structures in our catchments, flood plains and watercourses. These structures include pipes and open channel drainage networks, flood control systems and waterway crossings.


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