Coastal Wetlands of Indus River Delta Are Under Risk Due to Reclamation: A Spatiotemporal Analysis During the Past 50 Years From 1972 to 2022

Coastal wetlands are the most productive and biologically diverse ecosystems, benefiting both human populations and the total environment. However, they are continuously threatened by anthropogenic activities. Indus River Delta is the sixth largest in the world, has been adversely affected due to reclamation. The study examined the spatiotemporal dynamics of coastal wetlands and reclamation in the Indus River Delta from 1972 to 2022. Wetlands conversion to reclamation was extracted from 6-Landsat images. A land cover transfer matrix was used to analyze land use land cover (LULC) changes in different time intervals. Area-weight centroid was constructed to determine the migration trend of reclamation and coastal wetlands. Spatial accurateness was assessed using Producer's Accuracy (PA), User Accuracy (UA) and KAPPA coefficient (KC). The results reveal that from 1972 to 2022, the net area of wetlands declined by 1.9% (26.1 km²), while reclamation (settlement and cultivated land) increased by 14.7% (200.1 km²), and 27.5% (373.5 km²), respectively. The fastest areal change rate for coastal wetlands was −1.1 km²/year from 2012 to 2022, whereas the fastest areal change rate for settlement and cultivated land were 7.6 km²/year from 1992 to 2002 and 28.6 km²/year from 2012 to 2022. Centroids of wetlands moved slowly eastwards from Kharo Chan taluka to Keti Bandar in the first and third decades, then southwards in the second decade, later on, westwards in the fourth decade, and finally back southwards from Keti Bandar taluka to the Kharo Chan in the fifth decade with fastest movement. Centroids of settlement expanded in all directions over five decades. Centroids of cultivated land migrated westwards in the first, third and fourth decades, northwards in the second decade and southwards in the fifth decade from Keti Bandar to Kharo Chan. The findings of this study provide a scientific basis for sustainable land development and future planning.