Morphological change detection along the shoreline of Karachi, Pakistan using 50 year time series satellite remote sensing data and GIS techniques

Changes taking place along the shoreline are attributed to several physical and dynamical processes. Sindh Coast of Pakistan particularly Karachi is continuously under the process of morphological changes due to anthropogenic activities and natural processes. This study examined spatiotemporal morphological changes over five decades (1972–2020) along Karachi Coast bordering Arabian Sea using SRS and GIS techniques. This study reveals major morphological changes along the shoreline of Karachi in the vicinity of Karachi Port, Clifton Beach, Bundal Island and Port Qasim, which have been calculated in the form of erosion and accretion using erase tool of ArcGIS software. Quantitative analysis shows highest accretion of >15.50 km², at the Eastern End of Clifton Beach due to human intervention. Natural processes caused major erosion (10.95 km²) and accretion (19.50 km²) during 1972–2020 in the vicinity of Bundal Island. During 2011–2020, significant change (2.40 km²) is observed opposite to Port Qasim causing damage to mangrove vegetation of 1.40 km² calculated using NDVI. Highest rate of erosion (0.31 km²year⁻¹) and highest rate of accretion (0.70 km²year⁻¹) are found in Bundal Island during 1972–1987 and 1987–1999, respectively. Maximum increase in the length of shoreline (6.78 km) is depicted at Eastern End of Clifton Beech between 1999–2010.