Spatial variability in nearshore hydrodynamic regimes, morphodynamic zonation, and sediment transport along the southwestern Nigerian barrier–lagoon coastal system

Emmanuel Ike; Abdulkarim Rabiu; Idris Isa; Mohammed Auwal Yusuf

doi:10.61298/terratmosphera.2026.1.1.359

Authors

Emmanuel Ike [email protected] Department of Physics, Faculty of Physical Sciences, Modibbo Adama University, Yola, Nigeria
Abdulkarim Rabiu Department of Marine Geology/Geophysics, Nigerian Institute for Oceanography and Marine Research, Lagos, Nigeria
Idris Isa Department of Physics, School of Secondary Education and Science Program, Federal College of Education, Yola, Nigeria
Mohammed Auwal Yusuf Department of Physics, Faculty of Science, Yobe State University, Damaturu, Nigeria

Keywords:

Nearshore hydrodynamics, Morphodynamic zonation, Barrier–lagoon coast, Coastal evolution

Abstract

This study examines spatial variability in nearshore hydrodynamics and its implications for sediment transport and coastal evolution along the southwestern Nigerian barrier--lagoon coast. Field measurements (Seme, Yovoyan, Lekki, Okun-Ajah, and Orimedu) reveal pronounced alongshore heterogeneity in wave characteristics, breaker type distribution, and longshore currents. Plunging breakers dominate Seme (60 -- 90%) and Orimedu (70 -- 90%), indicating reflective to intermediate conditions, while Lekki is characterized by spilling breakers (80 -- 90%), consistent with a dissipative morphodynamic state. Okun-Ajah exhibits the highest wave energy (1.3 -- 1.5 m) and steep incidence angles (30 -- 45^o), marking it as the most dynamically active and erosion-prone sector. Breaker interval (0.16 -- 0.80 s) and wave inclination (10 -- 45^o) show strong spatial variability, reflecting differences in nearshore wave transformation processes. Longshore current velocities (0.17 -- 0.66 ms^-1) increase with wave obliquity, confirming wave direction as a key control on alongshore sediment transport. Statistical analyses reveal non-normal distributions and significant zonal differences in wave height, inclination, and breaker interval, with Okun-Ajah emerging with a high-energy anomaly. Strong co-variation between wave height and inclination (r=0.94) coupled with weak correlations with current velocity indicates that sediment transport is governed by interacting hydrodynamic and morphological controls rather than single forcing variables. Three hydrodynamic regimes are identified: dissipative (Lekki), reflective--intermediate (Seme--Yovoyan--Orimedu), and high-energy oblique-attack (Okun-Ajah), defining a morphodynamic gradient driven by spatial variations in wave energy flux and breaker angle. These findings offer a transferable framework for erosion risk assessment and shoreline management in wave-dominated barrier--lagoon environments.

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