Remote Sensing of Urban Forests in Nairobi City linking it to policy changes and implementation

Rapid urbanization in Nairobi (Kenya) is rapidly degrading its urban forests, threatening the city’s long-held identity as the “green city in the sun.” The loss of tree cover in Karura, Ngong Road Forest, and Oloolua reflects a broader problem of deforestation driven by development pressure and weak policy enforcement. This issue is particularly specific because Nairobi’s unique combination of rapid urban growth, legal gaps, and intense competition for land makes forest decline occur more severely here than in many other African cities. It also represents a distinct case where national legislation such as the Forest Act (2005) and EMCA (2015) exist but their implementation within an urban setting remains inconsistent. 

The data for this research included multi-temporal satellite imagery accessed through Google Earth Engine, focusing on Landsat and Sentinel datasets spanning 2000 to 2024. These datasets were used to generate vegetation indices such as NDVI to quantify forest cover change across the three major urban forests. Complementary policy documents, county urban planning records, and environmental legislation were analyzed to contextualize the observed changes. 

The methodology combined remote sensing analysis and GIS mapping using platforms such as Google Earth Engine and QGIS. NDVI computation, supervised classification, and change detection techniques were applied to assess temporal and spatial forest cover decline. This geospatial work will be integrated with qualitative policy evaluation to identify the governance gaps driving the ecological trends. 

The results showed a clear downward trend in forest cover over the last five decades, with sharper losses occurring during periods of accelerated urban expansion. We anticipated demonstrating misalignment between policy intentions and actual land-use outcomes, particularly were development overrides environmental protections. These results will likely reveal the need for stronger urban forest governance. 

This research is important because it offers a science-based understanding of how policy failures directly shape ecological degradation in growing cities. It contributes to the broader field of global environmental change by linking remote sensing evidence with governance analysis. Ultimately, the study provides an outlook for improving urban sustainability, guiding policymakers and planners in protecting Nairobi’s remaining forests while addressing future urban growth pressures.