Quantifying the Environmental Impact of Standard Gauge Railway (SGR) on Land Cover Changes along the Nairobi-Kiambu Corridor from 2016 to 2019

Transport infrastructure development can have significant negative impacts on natural resources over time and space, making it crucial to undertake careful consideration to minimize damage to both natural and artificial features. The objective of this study was to assess the magnitude of the environmental impacts caused by the standard gauge railway (SGR) from Nairobi Terminus to Nachu station in Kiambu county. The research approach used in collecting data, interpreting and analyzing the data was both quantitative and qualitative research. The study used a detailed GIS and remote sensing (RS) baseline environmental assessment and interviews to identify social and environmental impacts and proposed mitigation measures for the SGR project during and after implementation which is from 2016 to 2019. The results show that there was a 3.6% increase of built-up areas along the SGR line, while grassland, forest, and cropland decreased by 2.5%, 2.6%, and 13%, respectively. Increase in built-up areas has been identified to be around the railway station and also along the buffer zone The drivers of this change were mainly attributed to urbanization. Negative environmental effects of the SGR included encroachment on conservation areas, disruption of human settlement, and reduction of forest and vegetation cover. Noise and air pollution from SGR construction and operation affected wildlife, vegetation, and human settlements. To mitigate these negative impacts, this study recommends a number of measures including the wet-spraying of cement and wet drilling to reduce dust emissions during construction, frequent investigations of construction sites, afforestation, and GIS analysis to locate the most suitable SGR routes. Moreover. In conclusion, this study highlights the negative environmental impacts of the SGR project from Nairobi Terminus to Nachu station in Kiambu county. The results suggest that the project caused significant environmental degradation, particularly in terms of reduced forest and vegetation cover, and encroachment on conservation areas. The proposed mitigation measures can help reduce these negative impacts and minimize future damage caused by transport infrastructure development.