Geospatial Mapping and Monitoring of Sandbars in the Forcados River: Implications for Sustainable Blue Economy in the Niger Delta

Abstract

Understanding the spatiotemporal dynamics of sandbars along major river systems is vital for shoreline stability, sediment management, inland navigation, fisheries, aquaculture and coastal economy sustainability. This study investigates the mapping and monitoring of sandbars along the Forcados River in the Niger Delta, Nigeria, using geospatial tools and satellite imagery spanning 2003, 2013, and 2023. Utilizing high-resolution Landsat and Google Earth imagery, coupled with geospatial and morphometric analyses, the study identifies six major sandbars (SB1–SB6) and quantifies changes in their geometric, shape-based, and sedimentological parameters over the two-decade period. Results reveal consistent trends of lateral migration, expansion, accretion, and stabilization of sandbars, driven primarily by fluvial hydrodynamics, seasonal sediment flux, and upstream anthropogenic activities such as dredging and dam construction. The statistical relationship between length, width, and area yielded strong R² values (>0.96), indicating coherent geomorphic development across decades. Moran’s I spatial autocorrelation further highlighted a significant positive clustering (Moran's Index = 0.5147, p < 0.01) between sandbar locations and elevation. Grain size analysis based on the Folk and Ward method indicated predominantly medium to coarse sands with mesokurtic to leptokurtic distributions, suggesting moderate to high energy depositional environments. The findings contribute a geospatial database that supports riverine navigation planning, fisheries management, and aquaculture site suitability, while informing marine spatial planning and blue economy strategies. The study demonstrates the value of integrating remote sensing and spatial analysis for proactive river and coastal management, recommending sustained monitoring with drone photogrammetry and AI-enhanced tracking systems to build resilience in Nigeria’s coastal zones.