Recurrent Urban Flooding in Nairobi City: A Systematic Review of Environmental Determinants, Public Health Impacts and Policy Gaps
DOI:
https://doi.org/10.66050/ac1fpr38Keywords:
disaster, urban flooding, Nairobi, public health, climate change, diarrhoeal disease, riparian encroachment, urban planning, waterborne disease, KenyaAbstract
Nairobi has experienced recurrent and increasingly severe urban flooding over the past two decades. The April–May 2024 floods claimed between 267 and 294 lives and displaced approximately 380,000 people across Kenya, while the March 2026 flash floods — triggered by 112mm of rainfall within 24 hours — killed at least 66 people nationally and caused an estimated USD 300 million in infrastructure damage. These events reflect a systemic failure of intersecting environmental, structural, and governance determinants. This narrative systematic review (PRISMA 2020-adapted; final search: 31 March 2026) synthesizes evidence on the environmental determinants, public health burden, and governance gaps driving Nairobi's recurring floods. Searches across PubMed/MEDLINE, Scopus, Google Scholar, WHO IRIS, ReliefWeb, and national government portals identified 443 records, of which 68 sources met inclusion criteria across three evidence tiers. Five interconnected environmental determinants were identified: rapid unplanned urbanisation with significant green space loss; illegal encroachment on riparian reserves in violation of Kenya's 60-metre buffer zone mandate; ageing drainage infrastructure; intensifying bimodal rainfall amplified by climate change and El Niño; and upstream land degradation reducing catchment retention. Public health consequences include direct mortality, mass displacement, cholera and diarrhoeal disease outbreaks, vector-borne disease resurgence, and significant mental health burden, all disproportionately affecting informal settlement residents. Persistent governance gaps in land-use enforcement, flood risk assessment, inter-agency coordination, and community inclusion perpetuate this vulnerability. Lastly, 19 evidence-grounded recommendations are proposed across environmental, public health, and governance domains. Recurrent urban flooding in Nairobi is a preventable public health emergency amenable to structural intervention, with findings applicable to urban flood risk management across sub-Saharan African cities facing comparable intersections of rapid urbanisation, governance failure, and climate-change exposure.
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