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

Abstrakt

The Rosetta promontory, situated at the western mouth of the Nile Delta, represents one of the most erosion-vulnerable sectors of the Egyptian Mediterranean coastline. This study presents an integrated multi-temporal shoreline change analysis, employing satellite-derived DSAS mapping over 1999–2019 and 1999–2015 alongside grain-size and heavy-mineral analyses of shoreline sediments. Shoreline change analysis of 1999–2019 revealed a dominantly erosional regime, with a mean shoreline change rate of -3.65 m/year and a mean erosion rate of 7.92 m/year, affecting 70% of the total coastline. An extreme erosion rate of 32.51 m/year was recorded downdrift of the fifth eastern groyne, reflecting groyne-field-induced sediment transport discontinuity. Without management intervention, a mean coastline recession of 108 m and net land loss of 2.24 km² are projected by 2030. Heavy mineral concentrations ranged from 0.71 to 23.14 wt.% (mean 10.21 wt.%), with the majority of locations exceeding the 2 wt.% economic viability threshold. Shoreline change rates showed weak correlation with heavy mineral concentration (R = -0.37) and negligible correlation with mean grain size (R = 0.15), both variables substantially modified by anthropogenic coastal infrastructure. These findings highlight the urgent need for integrated coastal management strategies to mitigate accelerating land loss along this vulnerable deltaic coastline.