Frequency of floods and land use changes in Kibra and Mathare informal settlements, Nairobi, Kenya

Rapid urbanization and inadequate infrastructure exacerbate the risk of flooding in informal settlements, where 1.6 billion people live globally. This study, based on the theories of Political Ecology and Social Capital, explored the frequency of flood occurrence in Kibra and Mathare informal settlements in Nairobi City County, Kenya, where more than 60% of urban residents reside in informal settlements. The study adopted descriptive cross sectional research design with the target population being household heads, community leaders, non-state actors and state government agencies. Data was collected from 455 respondents (398 household heads, 42 focus group discussion participants, 10 non-state actors and 5 state actors) using multistage sampling techniques (stratified, purposive and simple random sampling). The primary data collection instruments were structured questionnaires, semi-structured interview guides, and focus group discussion guides, with secondary data and photographic evidence. Descriptive and inferential statistics were used to analyse quantitative data. The results indicated that 93.1% of the surveyed households experienced floods, with 47.9% experiencing 4-5 floods between 2020 and 2024. The spatial analysis showed that the flood prone areas have significantly increased from 2005 to 2024, with Kibra increasing from 0.8 km² to 2.0 km² and Mathare from 1.2 km² to 2.5 km². Household size (β=0.506, p=0.001) and average monthly income (β=-0.775, p<0.001) were significant predictors of flood frequency, explaining 47.5% of the variance. Land use analysis showed that built-up areas increased by 36% (Kibra) and 19.5% (Mathare) and riparian vegetation decreased by 56-57%, which reduced natural flood buffers. The study concludes that the flood risk in these settlements is chronic and structurally embedded, due to unplanned urbanization, ecological degradation and socio-economic inequalities. The results recommend the need for hyper-localised, ward-specific Disaster Risk reduction (DRR) strategies, combining engineered solutions with participatory planning and ecosystem-based strategies such as riparian restoration for sustainable urban resilience.