Urbanization and Flood Risk in Nairobi: A Historical Analysis of Settlement Patterns and Disruption of Riparian Systems
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Urban flooding has become a persistent challenge in rapidly growing cities, particularly in developing countries. Before urbanization and even before independence, Nairobi was defined by a dense network of rivers, streams, springs and wetlands that shaped its natural landscape. These natural systems facilitated infiltration, regulated water flow and minimized surface runoff, thereby making the early Nairobi landscape resilient to flooding. This study aimed to examine how urbanization has influenced flood risk in Nairobi through a historical analysis of settlement patterns and the disruption of riparian systems. This study employed a desk-based literature synthesis methodology utilizing secondary data analysis to examine the relationship between urbanization, riparian encroachment and flood risk in Nairobi's river corridors.Pre-1963 Nairobi maintained a highly efficient natural hydrological system comprising three primary perennial rivers, the Nairobi River (main stem), Ngong River and Mathare River. Landsat time-series analysis revealing built-up areas expanded 372% from 4.6% to 21.7% of riparian land coverage between 1992 and 2022. Vegetation cover declined 77% from 8.4% to 1.9% while water surfaces contracted 8.1% during the same period demonstrating clear causal progression from historical floodplain attenuation capacity through urbanization drivers to settlement encroachment, riparian disruption and flood amplification. Nairobi's recurrent urban flooding results directly from systematic riparian encroachment spanning 1963-2025.
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