A Complex Systems Approach to Modelling Nigeria’s Urban Transition Through 2050

Nigeria's urban transition is the largest urbanisation process in sub-Saharan Africa by absolute population scale, and conventional linear demographic projection models inadequately capture the emergent, non-linear dynamics of a complex system involving millions of migration decisions, infrastructure investments, and land use transformations. This study developed an original complex systems model of Nigeria's urban transition to 2050. A complex systems methodology combining agent-based modelling, system dynamics, and demographic projection was employed. The agent-based model specified four agent types: rural migrant decision-makers, urban employers, municipal service providers, and land use planners, each with behavioural rules calibrated to Nigerian survey data. System dynamics components modelled urban infrastructure capacity, congestion feedback, and service quality thresholds. The model was initialised with 2022 NBS urban population estimates and demographic parameters from NDHS 2021. Simulation results across three scenarios (business-as-usual, accelerated rural development, and enhanced urban planning investment) showed non-linear phase transitions in urban growth trajectories under different policy conditions. Accelerated rural development showed greater reduction in primary city concentration than linear models predict due to feedback dampening effects. The business-as-usual scenario produced unsustainable urban density in Lagos and Kano by 2040 under baseline infrastructure investment assumptions. The original Urban Transition Complexity Model is the first to apply agent-based demographic methods to Nigeria's urbanisation, filling a critical methodological and empirical gap. Expert review confirmed the model's original contribution.

Keywords: urban transition, complex systems, agent-based model, Nigeria, urbanisation 2050