Jul 2026· Sriwijaya Journal of Environment· Vol 11, pp. 65-74· 0 citations· 24 references
Abstract
Background: Coastal port infrastructure operates in dynamic tidal environments where seabed change threatens structural safety, yet high-resolution, standard-benchmarked bathymetric validation of damaged and replacement piles is scarce for West-African ports.
Objective: To characterise seabed conditions and validate proposed replacement piles at Bullnose Jetty, Apapa Port Complex, Lagos Lagoon, Nigeria, ahead of piling and repair.
Methods: A single-beam echo-sounder with RTK-GNSS and 10-minute tidal reduction produced a 0.1-m grid, interpolated by kriging (Surfer 16). The survey polygon was stratified into four hydrographic sub-zones (n = 108 nodes); six parameters were analysed by one-way ANOVA with Tukey HSD, Pearson correlation, multiple regression and PCA, and benchmarked against IHO S-44 (Ed. 6.0.0).
Results: Corrected depths ranged 10.1–13.2 m and differed significantly among zones (11.66±0.86 m; F(3,104)=131.0, p<0.001, η²=0.79), deepening from the quay apron (10.65±0.35 m) to the central channel (12.76±0.42 m). Achieved total vertical uncertainty (0.23–0.27 m, k=2) met IHO Order 1a everywhere and Special Order in sheltered zones, and was governed by roughness and depth (R²=0.82). PCA captured 86.3% of variance in two components. No obstructions occurred at piles A-38/39/40; the broken pile P39A was mapped on the seabed.
Conclusion: The reproducible, IHO-benchmarked protocol confirms safe pile placement and supports routine hydrographic monitoring of Lagos-area port infrastructure.
Accurate bathymetric data are essential for the design and monitoring of coastal structures, but conventional multibeam surveys are costly and often impractical in shallow or confined areas. We evaluate a single-beam echosounder (SBES, ECT400) suspended beneath an unmanned aerial vehicle (UAV) as a rapid method with low logistical requirements for bathymetric monitoring of coastal infrastructure. Fieldwork was performed in an operational dry dock that was alternately drained and filled, enabling direct geometric validation against an ultra-high-resolution photogrammetric DEM (0.55 cm GSD). The co-registered dataset comprises N = 16,137 sonar returns to depths of ≈ 8 m. The UAV-mounted SBES produced a mean depth difference of 0.15 m (SD = 0.58 m) relative to the photogrammetric reference. From these residuals we estimate a 95% Minimum Detectable Change (MDC95) of ≈ 0.5 m when changes are assessed by aggregating repeated co-located passes. These results indicate that the UAV-SBES workflow is suitable as a Tier-1 screening tool for structural-health monitoring, effective for detecting metre- to decimetre-scale changes and triaging sites for targeted high-precision follow-up, but not for micrometre/mm-scale deformation monitoring. The method’s portability and vessel-free operation make it especially useful for frequent inspections in shallow, confined coastal settings.
Bethsaide Souza-Santos, M. Arza-García, J. Ortiz-Sanz et al.· Journal of Civil Structural...· 0 citations
Coastal zones are increasingly exposed to climate change and rapid urbanization, yet the geomorphological stability of tropical, mud-dominated coastlines remains poorly understood. This study evaluates multi-decadal shoreline dynamics along a 250 km corridor of the Selangor coastline, Peninsular Malaysia, from 1990 to 2020. Using seven multi-temporal, sensor-homogenized Landsat datasets, baseline change metrics were computed via the Digital Shoreline Analysis System (DSAS v5.1). Historical shoreline shifts were quantified using the End Point Rate (EPR) and Linear Regression Rate (LRR) metrics to construct a process-based Geomorphological Stability Index (GSI). These historical vectors were coupled with IPCC AR6 sea-level rise anomalies to simulate scenario-based exposure projections for the 2030, 2040, and 2050 horizons. Baseline results revealed severe localized erosion hotspots exceeding -75 m/yr near the highly engineered Port Klang complex. The EPR network yielded a net erosional tendency of -0.15 m/yr, whereas the LRR model revealed a marginal net accretionary trend of +0.30 m/yr. The GSI framework classified 53.19% of the transects as highly stable/accreting (Rank 5) and 32.92% as severely eroding (Rank 1). Validation against an independent hazard inventory demonstrated a framework sensitivity of 100.0%. Scenario-based projections reveal intensifying erosive trends by 2050, accelerating mean EPR erosion to -5.14 m/yr and destabilizing up to 49% of the shoreline footprint. The findings provide actionable screening data to guide climate adaptation strategies.
N. Batmanathan, Joy Jacqueline Pereira, A. Shah et al.· Frontiers in Marine Science· 0 citations
The use of Satellite-Derived Bathymetry (SDB) constitutes an efficient, cost-effective, time-saving, and scalable approach for generating high-resolution shallow-water bathymetry. In this context, SDB can be proven to be a valuable method for supporting bathymetric surveys of submerged archaeological sites. This paper focuses on the ancient city of Asopos, located on the coast of the modern village of Plytra in Laconia, SE Peloponnese, Greece. The site occupies an extensive coastal area characterised by numerous ancient remains and geomorphological features distributed along the shoreline and within the nearshore zone. To achieve the objective of producing a very-high-resolution SDB map, one empirical and four machine learning approaches were evaluated: (a) the quadratic Stumpf band-ratio model; (b) Categorical Boosting; (c) Random Forest; (d) Extreme Gradient Boosting, with all models trained using the same three optimal spectral band ratios; and (e) the CatBoost model trained using principal components derived from a Principal Component Analysis of the multispectral dataset. These approaches were developed using multispectral WorldView-2 imagery and 208 in situ depth measurements as ground truth, collected across a different range of depths and distances from the coastline. Pan-sharpened imagery was used for visual interpretation. Model accuracy was assessed using an additional validation dataset of 57 depth measurements. This combined approach demonstrates that VHR SDB mapping of the nearshore zone is highly effective when employing three band ratios involving the blue, green, and yellow bands, achieving a root mean squared error of less than 1 m, and can therefore serve as a reliable method for shallow-water geoarchaeological investigations.
Aims: The study aims to measure ground-surface displacement and assess land subsidence along the under-monitored Terai belt of the Himalayan foothills using an open-source remote-sensing workflow.
Study Design: Observational time-series analysis utilising satellite radar interferometry to monitor surface deformation.
Place and Duration of Study: Pantnagar region, Udham Singh Nagar district, Uttarakhand, with acquisitions covering 8 January 2023 to 21 June 2026.
Methodology: Sentinel-1 interferograms were generated via the Alaska Satellite Facility’s HyP3 service and analysed using MintPy with the Small Baseline Subset (SBAS) method across 88 acquisitions. Following network inversion and digital elevation model error correction, pixels were masked at a temporal coherence threshold of 0.7, retaining 80.8% of the ~40 m grid. Results were evaluated against Dynamic World land-cover data, rainfall, and modelled groundwater storage.
Results: Most of the scene remained stable, showing a median line-of-sight velocity of −0.4 cm yr−1 (interquartile range: −1.2 to 0.0 cm yr−1; 1σ uncertainty: 0.06 cm yr−1). A distinct, linear subsiding zone in the south-west reached ~−6.1 cm yr−1, representing roughly 21 cm of cumulative line-of-sight displacement over 3.45 years. This deformation persisted over cropped farmland and showed no seasonal rebound during monsoons.
Conclusion: The persistent, non-rebounding subsidence points to inelastic aquifer-system compaction driven by sustained irrigation pumping. Although the rates remain provisional because nearby ground-station verification is unavailable, this methodology provides a reproducible template for regional Terai subsidence monitoring.
G. Verma, Rajeev Singh, Shikha Goswami et al.· Advances in Research· 0 citations
Early-stage offshore wind development in the Gulf of Tonkin (Bac Bo Gulf) requires environmental information beyond conventional wind-resource mapping. Waves, currents, directional relationships, and extreme conditions all affect structural loading, operability, and the reliability of preliminary feasibility assessments. Wind, wave, current, and bathymetric data for 1993–2024 were analysed at three representative fixed-bottom screening sites: northern Gulf of Tonkin (NGT), central Gulf of Tonkin (CGT), and southern Gulf of Tonkin (SGT). The analysis characterises long-term conditions, seasonal variability, directional misalignment, wind-conditioned sea states, and marginal extremes with quantified uncertainty. The central site was the most energetic, with a mean wind speed of 7.97 m s−1 at 150 m and a 50-year marginal wind return level of 37.67 m s−1; the southern site had the strongest background current and the most persistent wind–wave misalignment. These differences do not follow a simple north–south gradient, so a single regional environmental description would misrepresent at least one of the three sites. The resulting conditional, directional, event-associated, and marginal-extreme statistics were organised into an IEC-oriented screening framework rather than treated as completed design-load-case inputs. This framework gives developers a basis for comparing site-specific environmental conditions before committing to costly site investigations. However, joint environmental modelling, water levels, tidal and storm currents, site measurements, and load-response analysis remain necessary before detailed design and certification.
A critical factor in the transition towards renewable energies is offshore wind, and therefore efficient site investigation to assure the safety and stability of the wind turbines' foundations is needed. Conventionally, borehole drilling and in-situ testing are used. Although these techniques can provide accurate geological data, their costs are prohibitive and their scope of survey is restricted. This drives the need for complementary geophysical survey methods. The Single-Channel Seismic (SCS) method is a cost-effective and rapid technique that can be employed for regional seabed survey. However, low signal-to-noise ratio (SNR) and poor stratigraphic continuity result when applying conventional processing workflow on seismic data obtained from complex settings, such as thick sand layers, shallow water environment with the presence of strong multiples, and sea surface swell conditions. To overcome these problems, an optimized SCS processing workflow which introduces three new techniques is proposed: (i) eigenvalue based swell correction with adaptive sliding window smoothing, (ii) shearlet transform based sparse representation of seismic data to remove random noise, and (iii) combined predictive deconvolution (for short period multiples) and SRME with Bayesian separation (for long period multiples). This algorithm has been applied to a field data survey at Fangchenggang, Guangxi (water depths: 0-25 m, total area is 99 km 2 ), and a substantial increase is observed: SNR enhancement from about 8-12 dB (from comparison with F-K spectrum analysis), the stratigraphic continuity improvement by factor of about 2.5 (estimated by reflection event tracing), and elimination of over 70% multiple energy within targeted range. The final result successfully delineates bedrock topography and structural settings required for wind farm installation site investigation. This new approach makes it possible to enhance shallow-marine seismic data quality even with difficult geological conditions and extract information indispensable for offshore wind farm development.
Genwang Yi, M. Wei, Tao Pang et al.· Scientific Reports· 0 citations