Unveiling the 2022 Southern Pakistan Flood Footprint: Insights from Sentinel Imagery and Land Deformation Analysis

Abstract. Prior disaster management studies in the Indus flood plain of Pakistan have overlooked the potential of remote sensing for monitoring flood inundation zones over time. Still, there is a significant gap in understanding the impact of the devastating flood disaster on the land surface. Our research addresses this gap by utilizing multi-temporal Sentinel-1A, 2A, and ground-based validation surveys. This study uses the synthetic aperture radar interferometry (InSAR) technique to precisely characterize surface displacements resulting from the 2022 megaflood event in Pakistan. Our approach involves the analysis of SAR images captured from Sentinel-1A ascending passes, offering a comprehensive dataset for estimating land surface subsidence over the worst affected region in the Indus lower flood plain. The study’s findings indicate a subsidence ranging from -229.82 to -7.84 mm. The urban land subsidence along the Indus River was particularly concerning, with some areas experiencing a substantial displacement of -215.26 mm. Significant subsidence, greater than -100mm, affected 25.2% of the total study area. Agricultural land near the Indus River faced significant land displacement ranging from -180.82 to -7.84 mm due to the impact of floodwater. Additionally, regions with a maximum floodwater depth of 7 m exhibited higher land surface displacement. Floodwater depth was assessed using a Google Earth-based model. The primary causes of land displacement were excessive rainfall and the substantial flow of floodwater debris, requiring thorough attention from policymakers to ensure sustainable urban and agricultural development in the face of climate change.