Multi-Decadal shoreline dynamics of Ras El-Bar, Nile Delta: Unraveling human interventions and coastal resilience

Abstract

This study provided an updated assessment of temporal changes in shoreline of Ras El-Bar on the Nile Delta coast using multi-decadal data (1984–2024) of field observations, surveys, and measurements, supported by advanced remote sensing techniques. This temporally extended dataset allowed for a reliable assessment of human interventions on shoreline changes. Based on high-resolution imagery, from Landsat 1 (MSS), Landsat 5 (TM), Landsat 8 (OLI), and Landsat 9 (OLI-2), two methods were used for shoreline measurements between 1984 and 2024: the Modified Normalized Difference Water Index (MNDWI) and the Normalized Difference Water Index (NDWI)-based Digital Shoreline Analysis System (DSAS). The results suggest good consistency, with high confidence, between the two methods, with an average r value of 0.86, R² value of 0.92, and RMSE value of 23.11 m. The findings highlight the impact of Damietta Harbour (DH) on coastal morphodynamics, with continuous erosion observed over the Eastern Jetty (EJ) of the DH (sectors 1 to 4) from 1984 to 2020. From 2020 to 2024, the extension of DH’s jetties created a shadow zone with appreciable accretion east of EJ at sector 1. Moreover, the construction of the Aswan High Dam (AHD) induced sediment entrapment that nourished the coast. Several protection structures have been implemented to mitigate inundation and damage to infrastructure and to secure coastal stability along the Ras El-Bar resort. These structures include three groins, a revetment, eight detached breakwaters (DBWs), and four Y-shaped groins. Among these, the detached breakwaters have proven to be the most effective structures for ensuring coastal stability and maintaining a beach suitable for resort activities. These findings inform adaptive coastal management strategies to optimize tourism, protect critical infrastructure, and sustain natural coastal processes, providing policymakers with actionable insights to enhance the resilience of Ras El-Bar against erosion, sea-level rise, and climate change, while supporting sustainable development in this socioeconomically vital region.