Socio-Biophysical Flood Vulnerability Analysis in Urban Informal Settlements in Kenya

Abstract

Flooding in urban informal settlements (UIS) is often analysed through physical hazard exposure, yet risk extends beyond location. Social differentiation and political marginalisation also shape who is most affected, how impacts are experienced and ultimately how vulnerability is understood in UIS. Drawing on fieldwork conducted between May and August 2025 in Mukuru kwa Reuben, an informal settlement in Nairobi, Kenya, this study examines how biophysical, socio-economic, institutional and political factors interact to shape vulnerability to floods, situating the analysis within critical debates on urban informality and climate justice. Grounded in urban political ecology enhanced with gendered perspectives, the study uses a sequential mixed-methods approach that integrates GIS-based flood mapping, participatory mapping, focus group discussions, household surveys (N = 220) and policy analysis to capture both spatial patterns and differentiated lived experiences of vulnerability. The findings reveal that whereas low-lying topography and poor drainage drive exposure, vulnerability is intensified by insecure tenure, precarious livelihoods, gendered care burdens and overlapped and fragmented governance. Hybrid mapping uncovers localised ‘risk microenvironments’ often invisible to formal models, showing the benefit of plural methodology to capture complex and situated realities. The study advances flood vulnerability in UIS as a governance–exposure assemblage, showing how biophysical exposure becomes socially consequential through tenure insecurity, fragmented service provision, selective enforcement, unequal resource access, precarious livelihoods and uneven recognition of informal settlements in urban planning. Insights from Mukuru carry wider relevance for rapidly urbanising cities across Africa, showing that reducing flood vulnerability requires addressing not only hydrological exposure, but also infrastructural deficits, tenure insecurity, governance failures and entrenched inequalities.