Shoreline position trends in the Niger Delta: analyzing spatial and temporal changes through Sentinel-1 SAR imagery

Abstract

Various natural and human-induced processes operating across different temporal scales contribute to the spatial and temporal evolution of shoreline alterations. Deltaic coasts, particularly dynamic geomorphic systems, experience continuous changes at various spatial and temporal dimensions. This investigation underscores the effectiveness of Sentinel-1 Synthetic Aperture Radar (SAR) data in assessing long-term shifts in shoreline positions, focusing on the Niger Delta region. Out of 255 images from 2015 to 2020, 36 were selected based on high tide conditions for each year. This study has pioneered a straightforward and systematic approach rooted in Geographic Information Systems (GIS). This approach offers an accessible pathway for evaluating coastal changes in regions with limited data availability. To better comprehend the heterogeneity of change processes along the shoreline and to pinpoint their causes and mechanisms, we divided the shoreline into distinct sediment cells. This division adheres to a convenient and well-established methodology. This study identifies prevailing erosion trends outweighing accretion, with specific areas showing distinct erosion (cells II, IV, VI, VII, and VIII) and accretion (cells I, III, and V) patterns. Furthermore, coastal areas near river mouths exhibit a higher susceptibility to change. This approach offers a pathway for evaluating coastal changes in data-limited regions and can establish an effective monitoring system benefiting coastal modellers, scientists, and government agencies. It lays the groundwork for comprehensive coastal zone frameworks, facilitating improved planning and management strategies.