Impacts of Urbanization on Green Spaces of the Densely Populated City of Karachi, Pakistan - An Analysis of 8 Years of Data for Estimating Land Cover Changes

Abstract Growing population, uncontrolled migration, and unplanned urbanization are prevalent worldwide and Pakistan is no exception with Karachi ranking as Asia's fifth and the world's eleventh most populous metropolis. Urbanization is occurring at the expense of environmental degradation and a decline in the amount of Urban Green Spaces (UGS). The WHO recommends at least 9 square meters (m2) of green space per person, with a UGS value of 50 m2 per capital as the optimum green space for environmental sustainability. The study region consisted of six districts in Karachi, and their percentage of green space was calculated. Satellite images from the Landsat-8 Surface reflectance Tier-1 satellite program were used in this study. To perform calculations and detect land cover changes, the Normalized Difference Vegetation Index (NDVI), a widely used index to calculate the density of green area for a specific part of the land, is used. The results concluded that Karachi's green land cover has changed from 6.30% in January 2014 to 11.28% in January 2021, at NDVI > 0.3. These statistics of NDVI greater than 0.3 indicate sparse or moderate vegetation hence the possibility of including wild grass and bushes in the analysis is eliminated. Only a five percent (5%) rise over an eight-year period suggests the necessity for drastic action to improve the quantity and condition of UGS in Karachi. This study shows how Karachi's green spaces have been steadily being destroyed by uncontrolled urbanization and the yearly changes in vegetation. This research will help urban planners and policymakers to make wise choices for environmental sustainability in urban areas.