Land Use Policy Change and ITS Contribution to Urban Flooding in Downstream Zones: A Case of Nairobi City County

Urban flooding has become a significant problem in urban areas driven by land use policies. Inadequate flood mitigation measures in downstream zones have exacerbated the research problem. This study investigates the effects of changes in land use policies over time on urban flooding of downstream urban areas. Specifically, the study set out to assess the nature and trends of land use change and its implication, to determine the effects of land use policy change, and to examine the drivers of land use policy change and flooding on downstream zones in Nairobi City County. Finally, to propose strategies for sustainable land use policy change and protection of downstream zones from floods. The study employed quantitative and qualitative approaches that integrated secondary and primary data collection methods. Secondary data was gathered through archival methods. Land use policy, peer-reviewed journals and government records were reviewed using content analysis. Geographic information systems (GIS) mapping of remotely sensed data from Google Earth and Satellite Imagery completed the secondary data collection. Kobo Collect tools collected primary data through a survey and observation. The results indicate contradictions in land use policy changes from pre-independent to post-independent, particularly in the 2004, 2006, and 2022 policies. The policies have reduced the minimum plot sizes, increased the ground coverages and plot ratios, and increased the number of floors to more than 20 from the original two without concomitant changes in the support infrastructure. The study concludes that land use policy changes in Nairobi City County have increased surface runoff and flooding downstream zones. The study recommends comprehensively mapping the city’s drainage system utilizing remote sensing, GIS, and other methods. Furthermore, the study suggests that policy measures should critically consider the downstream by creating clear guidelines on land use policies that will help reduce surface runoff from the upstream.