Shoreline Change Assessment in the Orashi River, Rivers State, Nigeria, using the Digital Shoreline Analysis System (DSAS)

Abstract

Shoreline change profoundly impacts coastal geology and coastal communities. This study, spanning three decades from 1992 to 2022, employed the Digital Shoreline Analysis System (DSAS) to assess the Orashi River shoreline dynamics in Nigeria. Using Landsat imagery data from the United States Geological Survey (USGS) and ArcGIS 10.6, DSAS 5.0 software was utilized for analysis. Various statistical methods, including Linear Regression Rate (LRR), Weighted Linear Regression (WLR), End Point Rate (EPR), Net Shoreline Movement (NSM), and Shoreline Change Envelope (SCE), quantified shoreline changes. The findings consistently reveal significant shoreline regression. LRR, -1.78 to -1.07, highlights continuous landward movement, signifying erosion’s persistent impact. WLR rates reaffirm this trend, closely mirroring the range of -1.78 to -1.07. EPR, -2.79 to -1.29, further underline the erosional trend, emphasizing substantial inland shifts. NSM, ranging from -48.66 to -20.30, signifies substantial shoreline retreat, showcasing erosion’s profound effect. The NSM, varying from 0.69 to -11.50, illustrates dynamic shoreline movement with varying degrees of erosion. The outcomes identify prevalent erosion, particularly in Very High Erosion (VHE) areas, while High Accretion (HA) and Very High Accretion (VHA) zones experience shoreline gain. These classifications inform coastal management strategies, urging protective measures for VHE areas and development opportunities in HA and VHA zones. The variability in shoreline change underscores coastal dynamics’ complexity. This study contributes to understanding the Orashi River’s shoreline processes, guiding sustainable coastal management and environmental conservation efforts. Continued monitoring and research are crucial for adapting to the evolving coastal landscape’s impact on the environment and local communities.