Title: Investigation Of The Accuracy And Usefulness Of Satellite-Derived Bathymetry In High Wave Energy Areas Of A Tropic Estuary Cawthorne Channel To New Calabar River
Authors: AIMAH, PETER OGENAKHOGIE, PROF. FRANCIS I. OKEKE and DR. OBINNA C. D. ANEJIONU
Volume: 9
Issue: 11
Pages: 24-30
Publication Date: 2025/11/28
Abstract:
Bathymetric surveys are crucial for mapping the seabed but are costly, and traditional methods like echo sounders struggle in high wave transition zones. This study investigates the accuracy and reliability of Satellite-Derived Bathymetry (SDB) in high wave energy areas within a tropical estuary, specifically along the transition zone between Cawthorne Channel and New Calabar River in Nigeria's Niger Delta. Conventional bathymetric surveys using SONAR methods often encounter logistical and safety challenges in transition zones due to dynamic water conditions, limiting accurate depth acquisition. To address this, the research explores the utility of the Stumpf band-ratio model applied to Landsat-8 multispectral imagery, with a focus on assessing SDB's performance under turbulent estuarine conditions. In-situ bathymetric data were collected using multibeam and single-beam echo sounders to validate the satellite-derived results. Data processing involved radiometric, geometric, and atmospheric corrections, alongside sun glint and land-water separation procedures in ArcGIS. Results were analysed using statistical indicators such as Root Mean Square Error (RMSE), Mean Absolute Error (MAE), and the correlation coefficient (Rē). Findings revealed that SDB is significantly more accurate in calmer areas away from transition zones (Rē = 0.923; RMSE = 1.501 m) compared to turbulent zones (Rē = 0.571; RMSE = 1.433 m). These outcomes demonstrate that while SDB holds promise for shallow-water bathymetric mapping, its reliability decreases in high-energy environments. The study contributes to bridging the geospatial data gap in Nigeria's estuarine regions and highlights SDB's potential as a cost-effective complement to traditional hydrographic techniques in restricted-access zones. Overall, the study recommends adopting a hybrid approach that combines SDB with selective in-situ measurements, continuous local calibration, and the use of higher-resolution satellite imagery to enhance accuracy. Integrating SDB into national hydrographic programs could offer a cost-effective alternative for monitoring and mapping estuarine and coastal zones where traditional surveys are challenging.