Assessment of spatio-temporal changes in terrestrial carbon sequestration due to Kochi metro rail project in India

Major infrastructure projects can cause sizeable reduction in the urban tree cover thereby affecting terrestrial carbon sequestration potential of cities. This study investigated the spatio-temporal changes occurred in terrestrial carbon sequestration due to the metro rail project at Kochi city in India during the years 2013 to 2015. Normalized Difference Vegetation Index (NDVI) estimated from IRS-P6 LISS IV satellite sensor data was used to detect the tree cover change and for the quantification of carbon stock. An urban carbon storage equation was used to estimate the carbon content from NDVI values. Stock difference approach was used to estimate the change in carbon sequestration due to the construction of metro rail. Results indicated reduction of 14.51 ha of tree cover area within a distance of 60 m from the center-line of metro rail during the study period. Study found that 2316 tCO2e was emitted as a result of cutting urban trees for the metro rail. Such an emission was overlooked while estimating the emission reduction due to the promotion of public transport. This study points to the need for estimating the impacts of major urban infrastructure projects to the global climate in addition to assessing their mostly localized environmental impacts.