Complex adaptive learning for urban flood resilience : community-based nature-based solutions from Dar es Salaam, Tanzania

Abstract

Flooding in rapidly urbanising African cities reflects intertwined ecological degradation, institutional fragmentation, and socio-economic vulnerability. While Nature-Based Solutions (NbS) are increasingly promoted for flood management, there remains limited understanding of how community-driven Nature-Based Solutions contribute to resilience in flood management in the city. This study applies a Complex Adaptive Systems (CAS) framework to examine community-driven NbS in Ilala District, Dar es Salaam, focusing on how they operate as adaptive processes, generate flood resilience, and are influenced by institutional arrangements. Using a participatory stakeholder workshop involving 25 representatives from government, civil society, technical agencies, and flood-prone communities, data were analysed thematically through core CAS properties, including diversity, self-organisation, feedback, hierarchy, and emergence. Findings show that community-driven NbS function as dynamic, locally embedded, adaptive processes shaped by continuous interaction, learning, and collective action. Mechanisms of self-organisation, feedback, and social diversity enable communities to respond to hydrological variability, with resilience emerging from the integration of green and hybrid NbS, as well as local social organisation. However, these adaptive processes are conditioned by institutional environments characterised by weak coordination, limited integration into formal urban planning systems, and low private-sector engagement, which constrain long-term sustainability and scaling. The study emphasizes the importance of improved governance, inclusive decision-making, and sustainable financing to sustain and expand community-led NbS initiatives.