Remote sensing study of 30-year shoreline movement on the Rosetta promontory related to the spatial variations in sediment grain size and heavy mineral concentration

30-year shoreline change and sediment variations at Rosetta

Abstract

The Nile Delta coastline has undergone significant morphological changes since the early 20th century due to interconnected natural and human factors. A major turning point was the construction of the Aswan High Dam in 1964, which blocked sediment flow to the delta, accelerating coastal erosion. This study analyzed shoreline changes east and west of the Rosetta promontory using Remote Sensing and GIS techniques. Landsat images from 1999 to 2019 were processed, applying thresholding methods to distinguish land from water. Shoreline change rates were calculated using the Digital Shoreline Analysis System (DSAS) with the Linear Regression Rate method. The mean rate of shoreline change of -3.65 m/y was depicted between 1999 and 2019. Erosion averaged 7.92 m/year, while accretion averaged 4.02 m/year. About 69% of the 22.2 km study coastline experienced erosion, including nearly all (95%) of the western sector and 58% of the eastern sector. The highest erosion (32.51 m/year) and accretion (13.31 m/year) occurred east of the Rosetta promontory. The whole shoreline of 2030 will lose about 2.24 km² of its land unless additional protection structures are built. Heavy mineral distribution was also examined and found to vary with coastal morphology, though it showed weak correlation with shoreline change rates and grain size variations.