Evaluation of Climate Adaptation Strategies in Coastal Infrastructure Design in Cross River State

Climate change is altering sea level, storm surge frequency, and rainfall extremes in the coastal zone of Cross River State, South South Nigeria, requiring professional recalibration of infrastructure design standards to ensure adequate future performance. This study evaluates the adequacy of current infrastructure design standards for coastal conditions in Cross River State and develops climate adaptation design recommendations. A professional engineering assessment methodology was adopted, reviewing design standards applied in five coastal infrastructure projects (sea walls, road embankments, and drainage schemes) in Calabar, Bakassi, and Akpabuyo LGAs, using climate projection data from CMIP6 models for the South East Nigeria coastal zone. Projected sea level rise (high and medium emission scenarios), changes in extreme rainfall intensity, and storm surge enhancement over the 2050 and 2100 time horizons were quantified for design comparison. Results indicate that current sea wall design elevations based on historical tidal data will be submerged by 0.3 to 0.8 m under a 2100 medium emission scenario. Road drainage design standards based on 10-year return period storms underestimate projected 2050 design storms by 15 to 25 percent under high emission scenarios. The study proposes a Climate-Adjusted Design Standards Supplement for Cross River State Coastal Infrastructure, recommending 0.5 m additional freeboard on all coastal structures, uprated drainage standards, and 100-year economic appraisal horizons for all coastal capital projects.

Keywords: climate adaptation, coastal infrastructure, sea level rise, Cross River State, design standards