Structural Performance Assessment of Reinforced Concrete Drainage Channels in Kogi State

Reinforced concrete drainage channels are primary elements of flood management infrastructure in urban and peri-urban areas of Kogi State in the North Central geopolitical zone, where seasonal flooding causes recurring damage to property and livelihoods. This study assesses the structural performance of twenty reinforced concrete drainage channels in Lokoja, Okene, and Kabba, examining the condition of channel walls, invert slabs, expansion joints, and inlet and outlet structures. A structured inspection protocol was developed and applied, documenting crack patterns, section loss, joint failure, silting, and vegetation intrusion at each channel. Hydraulic capacity assessments were also conducted to determine whether existing channel cross-sections remain adequate given current urban runoff volumes. Results indicate that thirteen of the twenty channels exhibited structural distress rated as moderate to severe, with the predominant defects being longitudinal cracking of the invert slab and vertical cracking at construction joints attributable to differential settlement. Silting reduced the functional hydraulic cross-section by an average of thirty-eight percent across surveyed channels, significantly compromising drainage capacity during peak storm events. One channel section in Lokoja had suffered complete slab loss over a 12-metre stretch due to undermining by sub-slab erosion. The study recommends a prioritised rehabilitation schedule based on hydraulic and structural criticality ratings, mandatory desilt operations prior to each wet season, and redesign of expansion and construction joints using hydrophilic rubber waterstops. Keywords: drainage channels, structural performance, Kogi State, flooding, infrastructure rehabilitation.