Effect of Poor Drainage Systems on Road Pavement Performance in Idemili North Local Government Area, Anambra State: A Case Study of Nkpor

Effect of Poor Drainage Systems on Road Pavement Performance in Idemili North Local Government Area, Anambra State: A Case Study of Nkpor

Anene W.C., Okeke V.C

Lecturer, Department of Civil Engineering, Chukwuemeka Odumegwu Ojukwu University, Uli, Anambra state, Nigeria.

Nzife E, Okeke C.S., Iwuchukwu C.B, Okoloba O.D

Student, Department of Civil Engineering, Chukwuemeka Odumegwu Ojukwu University, Uli, Anambra state, Nigeria.

ABSTRACT – Premature pavement deterioration in urban road networks is largely caused by inadequate drainage systems, especially in tropical regions characterized by heavy rainfall. This study investigates the impact of insufficient drainage systems on road pavement performance in Nkpor, Idemili North Local Government Area, Anambra State, Nigeria. A field-based study methodology was adopted, which included reconnaissance surveys, systematic visual inspections, and basic measurements carried out on selected road segments. The assessment focused on observable pavement distresses, existing drainage system characteristics, and the relationship between drainage condition and pavement performance.

Field observations revealed that the drainage systems in the study area are predominantly open trapezoidal side drains that are shallow, discontinuous, and poorly maintained. Drainage deficiencies such as blocked channels, inadequate longitudinal slope, and lack of drainage continuity resulted in persistent water stagnation along pavement edges and shoulders. These conditions encouraged moisture ingress into pavement layers, leading to accelerated pavement deterioration, saturation of the base and subgrade, and reduction in shear strength and bearing capacity. Areas with inadequate drainage were found to exhibit more severe pavement distresses, including potholes, surface cracking, rutting, edge failure, and shoulder erosion.

The analysis concludes that pavement failure in Nkpor is primarily influenced by drainage inefficiency rather than traffic loading alone. Therefore, effective drainage continuity, proper drain design, and routine maintenance are essential for enhancing pavement performance and extending pavement service life in similar urban environments.

Keywords: Nkpor; surface runoff; urban roadways; drainage systems; pavement performance; pavement distress.

1. INTRODUCTION

   An efficient transportation and communication network is fundamental to socio-economic growth and national competitiveness. Functional systemssuch as roads, ports, and airports facilitate the safe and timely movement of people, goods, and services. However, Nigerias transportation sector has consistently ranked poorly in international assessments.

   Nigeria received particularly poor ratings for infrastructure in the Global Competitiveness Report (20102011), ranking 135th for overall infrastructure quality, 128th for road networks, 104th for rail/road integration, 121st for ports, and 101st for air transport. Overall, the country was placed 127th out of 139 nations assessed. Despite the fact that more than 90% of freight movement in Nigeria relies on the road system, only 50% of federal roads, 20% of state roads, and as little as 5% of rural roads are in good condition (Oni, 2009; Draft National Transport Policy, 2010).

   Beyond maintenance challenges, the rapid deterioration of Nigerian roads is strongly influenced by the quality of construction materials. Concrete, the primary component of road and drainage infrastructure, is highly sensitive to both the source of aggregate and the type of reinforcement used. Recent studies have confirmed this fact. For example, Okeke et al. (2023) modeled the strength

   of concrete produced with fine aggregates from Onitsha, Uli, and Njaba, demonstrating that aggregate source had a direct impact on compressive strength, with Uli aggregates yielding the highest values.

   In road pavement engineering, careful consideration of the geotechnical properties of soil is essential for ensuring pavement stability and durability(Ogunjiofor et al, 2026). These properties significantly influence how the pavement structure responds to water infiltration, particularly in situations where drainage systems are inadequate. Poor drainage conditions can alter the strength, bearing capacity, and overall performance of the subgrade soil, thereby accelerating pavement deterioration.

   The absence of adequate drainage systems further exacerbates the deterioration of Nigerian roads. In both urban and rural communities, insufficient drainage contributes to frequent flooding, erosion, and pavement failure (Olukanni, 2013a; WHO/UNICEF, 2012). Rapid population growth without corresponding expansion of infrastructure intensifies these challenges (Banerjee & Morelia, 2011). As Dawson (2008) observed, water infiltration substantially reduces pavement bearing capacity, thereby accelerating premature failures.

   Responsibility for Nigerias road network is divided among the three tiers of government: local governments manage Trunk C rural and feeder roads (66%), state governments oversee Trunk B roads (17%), and the federal government controls Trunk A roads (17%). Despite this distribution, more than 65% of the countrys 198,000 km road network remains in poor condition. The Central Bank of Nigeria (2003) estimated that bad roads cause annual losses of approximately 133.8 billion, excluding ancillary costs such as vehicle repairs, reduced productivity, and the psychological stress imposed on road users.

   Therefore, it is evident that Nigerias road failures are primarily driven by two critical factors: inadequate drainage design and the use of substandard construction materials. Addressing these challenges requires both the incorporation of efficient drainage systems and the adoption of durable, research-based concrete materials. Recent research by Okeke et al. (2023), which modeled the strength of concrete produced with fine aggregates from different sources, provides valuable insights into material optimization strategies that can enhance the performance and sustainability of road and drainage infrastructure in Nigeria.

   In a related regional investigation, Anene et al. (2025) conducted a Comparative Analysis of the Geotechnical Properties of Soil for Road Subgrade in Anambra State: A Case Study of Onitsha, Nnewi, Awka, and Ihembosi. Their study demonstrated that variations in soil texture, plasticity, and permeability significantly affect both pavement durability and drainage performance. Findings revealed that local geotechnical conditions determine how efficiently drainage structures convey surface runoff and resist subsurface seepage. These results align with the present research at Nkpor in Idemili North LGA, where inadequate drainage and unstable subgrade soil have contributed to premature pavement failures. Integrating the insights of Anene et al. (2025) provides a stronger contextual foundation, highlighting that sustainable road infrastructure in Anambra State depends on coordinating drainage efficiency with geotechnical suitability before construction.

2. LITERATURE REVIEW

   The causes of road failure and the influence of construction materials and drainage on pavement durability have been extensively examined in academic research. Dawson (2008) emphasized the significance of drainage design in road construction, demonstrating that water infiltration into pavement layers reduces bearing capacity and accelerates deterioration. Oni (2009) identified flaws in Nigerias transportation strategy, linking poor road conditions to inadequate planning ad insufficient maintenance. Similarly, the World Economic Forum (2010) reported that Nigeria scored poorly on the global infrastructure competitiveness index, with roads highlighted as a major constraint to socio-economic development.

   WHO/UNICEF (2012) and Olukanni (2013a) reported that inadequate drainage systems in Nigerian cities are major contributors to pavement failure, erosion, and flooding. Amit (2016) further emphasized that poorly designed or poorly maintained drainage facilities increase the frequency of maintenance interventions, compromise road safety, and disrupt transportation services.

   Previous research has also emphasized the critical role of material quality in road performance. LASDTM (2004) explained that the use of weak subgrade and sub-base soils without adequate stabilization results in premature failures such as rutting, potholes, and cracking. Abdulkareem (2010) highlighted the importance of selecting appropriate materials for road layers to withstand both traffic and environmental loading. Similarly, Moulton (1980) described the structural functions of road layers, stressing the role of base and binder courses in distributing stresses and ensuring long-term durability.

   Okeke et al. (2023) conducted a study modeling the strength of concrete produced with fine aggregates from Onitsha, Uli, and Njaba in southeastern Nigeria, which is particularly relevant to the present investigation. Their findings revealed that aggregate source had a significant effect on compressive strength, with Uli aggregates achieving the highest mean value at 28 days. Using Response Surface Methodology (RSM), the study validated predictive models that demonstrated the critical role of aggregate quality in producing durable concrete. In the Nigerian context, where rapid pavement deterioration is frequently linked to poor concrete quality, these findings are especially significant.

   The importance of effective drainage in ensuring road performance has also been highlighted in several studies. The Highway Design Manual (2001) and Annie-Claude (2009) described drainage techniques such as open drains, piped drains, and French drains, which are selected based on groundwater conditions, road type, and terrain. Mwangi (2013) further emphasized that surface drainage components including pavements, shoulders, side drains, curbs, gutters, culverts, and storm sewers must operate as an integrated system to prevent water infiltration into the pavement structure and to ensure long service life.

   Building upon related studies, Anene et al. (2025) conducted a Comparative Analysis of the Geotechnical Properties of Soil for Road Subgrade in Anambra State, focusing on Onitsha, Nnewi, Awka, and Ihembosi. Their research emphasized that subgrade soil texture, plasticity, and permeability greatly influence both pavement durability and drainage performance. The findings indicated that clayey subgrades retain water, reducing bearing capacity and accelerating surface failure, whereas granular soils improve infiltration and load support. These observations provide essential insight for drainage and pavement design in Anambra State. The study further supports the present research by linking poor subgrade conditions to frequent drainage blockages and premature road deterioration observed within Nkpor in Idemili North LGA.

   Nigeria faces significant drainage challenges, including inadequate drains, urban flooding, and poor maintenance practices. Olukanni (2013a) reported that flooding in Nigerian cities is frequently caused by clogged and undersized drains, while WHO/UNICEF (2012) linked drainage deficiencies to public health risks such as mosquito breeding and waterborne diseases. Amit (2016) further noted that drainage failures impose major economic costs by damaging infrastructure and disrupting transportation systems. Collectively, these findings confirm that inadequate drainage and substandard construction materials are the primary drivers of road failure. The present study seeks to address this gap by integrating drainage performance with material optimization, an area that has received limited attention in the Nigerian context.

3. MATERIALS AND METHODOLOGY
   1. Research Methods

      This study examines the impact of inadequate drainage systems on road pavement performance in Nkpor, Idemili North Local Government Area, Anambra State, using a descriptive field-based research design. The research approach emphasizes systematic field observations, basic in-situ measurements, and visual condition assessments of road pavements and associated drainage infrastructure within the study area.

      The descriptive research design is appropriate for this study as it enables direct evaluation of existing pavement and drainage conditions without altering the physical environment. Based on observed site conditions, this approach facilitates the identification of drainage-related pavement distresses, assessment of drainage adequacy, and evaluation of the influence of drainage conditions on pavement performance.

   2. Description of Study Area

      Nkpor is situated along a significant transit route that connects Onitsha, Awka, and Nnewi in Idemili North Local Government Area of Anambra State, Nigeria. The region is strategically important for residential growth, commercial activities, and intra-urban mobility. It is characterized by heavy rainfall typical of the tropical rainforest climatic zone, high traffic volumes, and rapid urban expansion, all of which place considerable strain on the existing road and drainage infrastructure.

      Nkpor experiences high annual rainfall, elevated relative humidity, and moderate to high temperatures, all of which significantly influence pavementdrainage interactions and surface runoff generation. The topography is predominantly low-lying with gentle undulations, which limits natural drainage and promotes water stagnation in areas with inadequate or poorly maintained drainage systems.

      As a result, surface runoff accumulation, drainage blockages, and water stagnation during the rainy season frequently lead to pavement distresses such as potholing, surface ravelling, edge failure, and subgrade weakening. Owing to these characteristics, Nkpor provides a representative environment for assessing the effects of inadequate drainage systems on pavement performance.

   3. Research Materials

      In line with the objectives and scope of this study, the materials used were limited to those required for field observation, basic measurements, and documentation. The materials included:

      Measuring tape used for measuring pavement width, drain width, and drain depth

      Camera-equipped mobile device used for photographic documentation of pavement and drainage conditions

      Field notebook and pen used for recording field observations Pavement distress identification checklist

      Drainage condition assessment checklist

      These materials enabled accurate observation and documentation of pavement conditions and drainage features without the need for laboratory testing or advanced instrumentation.

   4. Data Collection Technique

      Field reconnaissance surveys and systematic visual inspections of selected road segments within Nkpor were used to collect data for this study. Preliminary site visits were conducted to identify road segments with evident pavement deterioration and drainage deficiencies. Field observations focused on the types and severity of pavement distresses, the availability and condition of drainage facilities, evidence of surface water stagnation along pavement surfaces and shoulders, and the relationship between drainage conditions and pavement failure locations.

      Where necessary, basic measurements such as pavement width and drain dimensions were taken using a measuring tape. Photographic documentation was employed to support field observations and provide visual evidence o pavement and drainage conditions.

      To ensure that conclusions were grounded in actual field conditions within the study area, the collected data were analyzed qualitatively to identify patterns linking inadequate drainage systems to pavement deterioration.

4. RESULTS AND DISCUSSION
   1. Overview

      The results of field reconnaissance surveys, systematic visual inspections, and basic measurements carried out on selected road segments in Nkpor, Idemili North Local Government Area, Anambra State, are presented and discussed in this chapter. The characteristics of existing drainage systems, documented pavement distresses, and the relationship between drainage deficiencies and pavement performance are highlighted. The discussion is supported by schematic representations (Figures 4.14.3) derived from field observations and interpreted using established principles of highway drainage and pavement engineering.

   2. Existing Features of the Drainage System

      According to field observations, open trapezoidal side drains make up the majority of the drainage systems in the study area. Many of these drains were found to be inadequately maintained, shallow, and discontinuous, which limited their ability to efficiently convey surface runoff. Along a number of drainage channels, sediment deposition, vegetation growth, and solid waste accumulation were frequent occurrences, causing partial or total blockage.

      Water stagnation was often observed along pavement shoulders and edges, especially in low-lying areas and locations where drainage continuity was disrupted. These conditions suggest that the existing drainage systems are ineffective in safely removing surface runoff from the pavement structure, thereby increasing the risk of moisture-related pavement damage.

      1. Typical Section of an Open Trapezoidal Drain

         Figure 4.1 shows a typical section of an open trapezoidal drain observed in the study area. To collect surface runoff, the drain consists of sloping side walls and a flat base located adjacent to the pavement shoulder. Field investigations revealed that the base width and drain depth were sometimes insufficient to accommodate runoff during periods of intense rainfall. As a result, overflow frequently occurred, allowing water to encroach onto the shoulders and pavement surface. This condition increases the likelihood of moisture infiltration into pavementlayers, particularly in the vicinity of pavement edges.

         Figure 4.1: Typical Section of an Open Trapezoidal Drain Observed in the Study Area

      2. Longitudinal Profile of an Open Trapezoidal Drain

         The longitudinal profile of the open trapezoidal drain shown in Figure 4.2 illustrates variations in drain slope along the roadway. A number of drain segments exhibited inadequate longitudinal slope, which caused water within the channel to flow slowly or remain stagnant. Poor longitudinal slope was observed to encourage sediment accumulation, which further reduced drainage efficiency and increased the frequency of blockages.

         Pavement distresses such as potholes and edge failure were more pronounced in areas characterized by sediment accumulation and stagnant water.

         Figure 4.2: Longitudinal Profile of an Open Trapezoidal Drain Showing Water Stagnation and Sediment Accumulation

      3. Plan View of Open Trapezoidal Drain Along the Roadway

         Figure 4.3 shows the plan view of the drainage system along the roadway. The alignment and continuity of open trapezoidal drains with respect to the pavement are illustrated in the figure. Field investigations showed that drainage continuity was frequently interrupted, particularly at road crossings, access points, and locations where drains were blocked or abruptly terminated.

         These disruptions to natural runoff flow result in localized water accumulation along pavement edges and shoulders. Such conditions significantly contribute to shoulder erosion and pavement deterioration within the study area.

         Figure 4.3: Plan View of an Open Trapezoidal Drain Along the Roadway Showing Drainage Discontinuities

   3. Pavement Conditions and Distresses Observed

      Potholes, surface cracking, rutting, edge failure, and shoulder erosion were among the pavement distresses observed along the surveyed road segments. In areas with inadequate drainage, these distresses were significantly more severe and widespread. Potholes were frequently observed in locations experiencing prolonged water stagnation, while edge failure and cracking were prevalent around blocked drains and drainage discontinuities.

      Rutting and surface deformation were evident in areas where subgrade saturation was observed, indicating moisture-induced weakening of the pavement support layers.

   4. Relationship Between Pavement Performance and Drainage Condition

      Within the study area, a direct relationship between pavement performance and drainage condition was observed. Road sections with relatively functional and continuous drainage systems exhibited better pavement condition, whereas sections with blocked, shallow, or discontinuous drains showed severe pavement deterioration. Pavement failures were consistently observed to initiate near drainage-deficient locations, indicating that moisture infiltration resulting from inadequate drainage is a significant contributor to pavement failure in Nkpor.

      This finding emphasizes the importance of effective drainage in maintaining pavement structural integrity and long-term performance.

   5. Discussion of Results

      The results of this study show that, in Nkpor, Idemili North Local Government Area, Anambra State, inadequate drainage systems significantly contribute to the acceleration of pavement deterioration. Persistent water stagnation along pavement edges and shoulders is caused by lack of drainage continuity, obstructed channels, insufficient longitudinal slope, and inadequate drain depth.

      From an engineering perspective, poor drainage facilitates moisture ingress into pavement layers through joints, cracks, and pavement edges. As a result, the base and subgrade layers become saturated, reducing the pavements shear strength and bearing capacity and increasing its susceptibility to deformation under repeated traffic loading.

      Pavement distresses such as potholes, surface cracking, rutting, and edge failure are consistent with moisture-induced damage mechanisms commonly documented in highway engineering practice, particularly in tropical regions characterized by high rainfall. Overall, the findings indicate that drainage inefficiency rather than traffic loading alone plays a significant role in pavement failure within the study area. Therefore, improving drainage continuity, ensuring adequate drain geometry, and implementing routine maintenance are essential measures for enhancing pavement performance and extending pavement service life in Nkpor.

5. CONCLUSION AND RECOMMENDATIONS
   1. Conclusion

      This study used field reconnaissance surveys, systematic visual inspections, and basic measurements to investigate the impact of inadequate drainage systems on road pavement performance in Nkpor, Idemili North Local Government Area, Anambra State. The results showed that surface runoff is not effectively removed by the existing drainage system, which is primarily composed of open

      trapezoidal side drains that are generally shallow, discontinuous, and poorly maintained. Drainage deficiencies such as blocked channels, insufficient longitudinal slope, and lack of drainage continuity were directly linked to persistent water stagnation along pavement edges and shoulders.

      These conditions encourage moisture ingress into pavement layers, leading to saturation f the base and subgrade, reduction in shear strength and bearing capacity, and accelerated pavement deterioration. As a result, locations with inadequate drainage exhibited more severe pavement distresses, including potholes, surface cracking, rutting, edge failure, and shoulder erosion. Overall, the study shows that drainage inefficiency has a greater influence on pavement failure in Nkpor than traffic loading alone, highlighting the critical role that effective drainage plays in preserving pavement performance in tropical regions characterized by high rainfall.

   2. Recommendations

Based on the findings of this study, the following recommendations are made:

Drainage Continuity: Existing drainage systems should be rehabilitated to ensure continuous runoff conveyance along road corridors, especially at intersections, access points, and low-lying sections.

Adequate Drain Geometry: Open trapezoidal drains should be provided with sufficient depth and longitudinal slope to prevent water stagnation and sediment accumulation.

Drainage Appurtenances: Functional appurtenances such as catchpits, silt traps, and properly protected outfalls should be incorporated to improve drainage efficiency and reduce blockage.

Routine Maintenance: Regular desilting, vegetation removal, and solid waste clearance should be carried out to sustain drainage performance and extend pavement service life.

Integrated Pavement Management: Drainage considerations should be fully integrated into pavement design, construction, and maintenance planning to reduce premature pavement failure and enhance road serviceability.

REFERENCES

1. Abdulkareem, A. (2010). Principles of highway engineering and traffic analysis. Lagos, Nigeria: Highway Press.
2. Amit, K. (2016). Highway engineering and drainage management. New Delhi, India: Techno-Science Publications.
3. Anene, W. C., Ikpa, P. N., Njoku, K. O., Emeribe, H. E., Ahuimbe, K. A., Ibekwe, O. S., & Okeke, C. S. (2025). Comparative analysis of the geotechnical properties of soil for road subgrade in Anambra State: A case study of Onitsha, Nnewi, Awka, and Ihembosi. International Journal for Research in Applied Science & Engineering Technology (IJRASET), 13(9), 20012005. https://doi.org/10.22214/ijraset.2025.74226
4. Annie-Claude, L. (2009). Drainage systems in road construction: Design and performance considerations. Paris, France: Transport Research Institute.
5. Banerjee, S., & Morelia, F. (2011). Urban population growth and infrastructure challenges in developing nations. Journal of Urban Development Studies, 18(2), 4559.
6. Central Bank of Nigeria. (2003). Annual report and statement of accounts. Abuja, Nigeria: Author.
7. Dawson, A. (2008). Water in road structures: Movement, drainage and effects. Dordrecht, Netherlands: Springer. https://doi.org/10.1007/978-1-4020-8562-8
8. Dawson, A. (2008). Water in road structures: Movement, drainage and effects. Dordrecht, Netherlands: Springer. https://doi.org/10.1007/978-1-4020-8562-8
9. Draft National Transport Policy. (2010). Draft national transport policy for Nigeria. Federal Ministry of Transport, Abuja, Nigeria.
10. Highway Design Manual. (2001). Highway design standards and drainage practices. Washington, DC: Federal Highway Administration.
11. LASDTM. (2004). Road and traffic management guidelines. Lagos, Nigeria: Lagos State Department of Transport and Management.
12. Moulton, L. K. (1980). Structural design of pavements. Washington, DC: U.S. Department of Transportation, Federal Highway Administration.
13. Okeke, C. S., Ogunjiofor, I. E., & Mbawuike, C. K. (2023). Modeling of strength of concrete produced with fine aggregates from different sources. International Journal for Research in Applied Science & Engineering Technology, 11(12), 17881796. https://doi.org/10.22214/ijraset.2023.57598
14. Okeke, C. S., Ogunjiofor, I. E., & Mbawuike, C. K. (2023). Modeling of strength of concrete produced with fine aggregates from different sources. International Journal for Research in Applied Science & Engineering Technology, 11(12), 17881796. https://doi.org/10.22214/ijraset.2023.57598
15. Olukanni, D. O. (2013a). Assessment of drainage facilities in developing urban centers: A case study of Ogbomoso, Nigeria. International Journal of Engineering and Technology, 3(2), 122129.
16. Olukanni, D. O. (2013a). Assessment of drainage facilities in developing urban centers: A case study of Ogbomoso, Nigeria. International Journal of Engineering and Technology, 3(2), 122129.
17. Oni, S. I. (2009). Development of transport policy in Nigeria. Journal of Policy and Development Studies, 3(1), 1521.
18. Oni, S. I. (2009). Development of transport policy in Nigeria. Journal of Policy and Development Studies, 3(1), 1521.
19. Ogunjiofor, E.I., Anene, W.C., Okinyi, C.J., Chibuife,M., Ajayi, D.I., Chukwuemeka, M.C.,Nwankwo, J.C(2026). Spatial Distribution and Characteristics of Soil Particles of Ihiala Localities, Anambra State, Nigeria. International Journal of Engineering Development and Research. Volume 14(1),62-76.
20. World Economic Forum. (2010). The Global Competitiveness Report 20102011. Geneva, Switzerland: Author.
21. World Economic Forum. (2010). The Global Competitiveness Report 20102011. Geneva, Switzerland: Author.
22. World Health Organization [WHO], & United Nations Childrens Fund [UNICEF]. (2012). Progress on drinking water and sanitation: 2012 update. Geneva, Switzerland: WHO/UNICEF Joint Monitoring Programme.
23. World Health Organization [WHO], & United Nations Childrens Fund [UNICEF]. (2012). Progress on drinking water and sanitation: 2012 update. Geneva, Switzerland: WHO/UNICEF Joint Monitoring Programme.