Bathymetry Research Articles

Monitoring long-term water storage of lakes and reservoirs in arid ungauged basin based on underwater topography derived from multi-source satellite data

Monitoring long-term water storage of lakes and reservoirs in arid ungauged basin based on underwater topography derived from multi-source satellite data

GIS-Based Geostatistical Techniques for Sedimentation Assessment Using USV Data: Case study Tuplang Reservoir, Uzbekistan

This study investigates the impact of sedimentation on the storage capacity of the Tupalang Reservoir, located in Surkhandarya, Uzbekistan, over a period of more than 30 years. Sedimentation poses a significant challenge by gradually reducing reservoir capacity, affecting water availability for irrigation, hydropower, and drinking supply. In the study, sedimentation was evaluated using GIS-based geostatistical methods using USV data in the reservoir. For the bathymetric data processing that was collected in 2023, four interpolation techniques—IDW, RBF, OK, and EBK —were applied, with RBF demonstrating the highest predictive accuracy. Results indicate a capacity loss of 28.05 million cubic meters (Mm³), or 5.65% of the total volume, primarily in the dead storage zone between 830 m and 890 m above sea level. Using bathymetric surveys conducted in 2003, 2007, 2010, and 2023, this research assesses changes in reservoir volume and identifies sedimentation patterns. The findings highlight a decline in sedimentation rates from 1.51 Mm³ per year in the early years to 0.3 Mm³ per year after 2010, attributed to effective management practices such as hydraulic washing. The study underscores the importance of proactive sediment management strategies, including dredging and sediment traps, to sustain reservoir functionality and recommends ongoing monitoring using advanced geospatial techniques

Generalization of the underwater relief image using the spline approximation method on a vector electronic chart

Special attention is paid to the need for reasonable generalization aimed at adequately displaying the characteristic features of the seabed relief profile in accordance with the principle of navigational isosurface in electronic visualization of underwater relief. It is assumed that as a result of generalization of the bottom relief, safety contours can be extracted directly, since they represent traces of a cross-section of the profile of the underwater relief with horizontal planes. A hypothesis has been put forward on the applicability of the B-spline approximation for modeling a safety contour in order to effectively implement a practical guarantee against grounding a ship. A modification of the safety contour based on the control of the smoothness of the constructed curve in the form of bending of a serpentine B-spline structure has been tested. An analysis of the optimality of configuring B-splines on a variable type of supports is carried out with the determination of preference for the cubic case. The straightening of the safety contour focuses on local deformation while maintaining strategic descriptive characteristics. The use of the smoothing procedure on the deep side of the safety contour is justified, provided that the basis points of the synthesized curve are artificially preserved. The data of the author’s computational experiment on the accuracy of calculation by cubic B-splines with a result two orders of magnitude higher than theoretically predicted are presented. It is noted that the technologies of automated processing of bathymetric survey results do not replace the human factor, but provide the potential to unlock new cognitive capabilities of an expert in the transition from lithographic publications to digital cartographic products. The arsenal of basic piecewise approximation is interpreted as the variability of the model of an additive B-spline neural network to provide an incentive for the use of artificial intelligence to generalize contour lines of marine subjects. It is emphasized that the spline technology, by its mathematical architecture, is basically devoid of the computational problem of dimensionality, which serves as an additional factor for the use of piecewise approximation in solving complex navigation tasks.

Geomorphic time series reveals the constructive and destructive history of Havre caldera volcano, Kermadec arc

Monitoring active seafloor processes requires repeated, comparable surveys to enable change detection. The change detection of the deep ocean floor, however, is rare due to a paucity of repeat data at an appropriate resolution. In this study, we use an exceptional suite of bathymetric surveys across a spatiotemporal range at the submarine Havre volcano, Kermadec arc, Southwest Pacific, to investigate geomorphic change over 13 years (2002, 2012, and 2015). The integration of bathymetric observations with remotely operated vehicle (ROV) observations and sampling data refined geomorphic boundaries, and four geomorphic groups at varying scales are interpreted: (i) large-scale tectonic and volcanic features, e.g., faults and calderas; (ii) coherent volcanic products, e.g., lavas; (iii) clastic primary volcanic products, e.g., giant pumice deposits; and (iv) mass-wasting features and products, e.g., landslide scarps. Three 25-m resolution geomorphic maps for broad-scale feature change and high-resolution 1-m autonomous underwater vehicle (AUV) bathymetry are used to develop a fine-scale geomorphic map that reveals additional landforms and processes. We integrate bathymetric data with sampling data and ROV video footage of the seafloor to refine geomorphic boundaries. We also integrate the results of previous geological studies of Havre to inform the geomorphic interpretation. Our map reveals a variety of geomorphic forms from a range of volcanic and mass-wasting processes that aid in the interpretation of the growth and evolution of submarine volcanoes. One new observation reveals a significantly larger scale of cryptodome emplacement than recognized previously recognized, accounting for an additional volume of 0.0055 km3 to the 2012 eruption products. This emplacement took place along two linear southern caldera ring faults and likely continued after the formation of the giant pumice raft on 18 July 2012. A key result is the extension of the timeline for the emplacement of volcanic products associated with the 2012 eruption, revealing an additional volume growth of 0.001 km3 on the primary dome (dome OP) between 2012 and 2015. This additional emplacement is documented in this study for the first time and extends the known volcanic emplacement timeline from 3 months to a maximum of 3 years. Our work reveals seafloor modification continuing long after an observed volcanic eruption event as lingering lava emplacement and mass wasting remobilize newly erupted and older products that comprise the edifice.

A systemic approach to managing uncertainties in repetitive multibeam bathymetric surveys

A systemic approach to managing uncertainties in repetitive multibeam bathymetric surveys

Optimal Interpolation Method for Generating a Digital Bathymetric Model for Shallow Waters: A Case Study over Mauritius Coast

Bathymetry unveils the underwater topography of oceans, seas, rivers, and lakes. It is a fundamental data resource for various applications, like physical oceanography, marine geology, geophysics, and marine resources. The techniques to compute the seafloor depths are ship-borne echo sensors, empirical models of satellite-derived bathymetry, and aerial-space-borne laser altimetry. The digital bathymetric surfaces are generally generated from a distributed seafloor depths. Once these depth points are collected, the next step to generate a continuous surface is to select and implement interpolation. Numerous interpolation methods have advantages and disadvantages that can hamper the accuracy of the surface, which generally depends on the shape of the extent, distribution, and point density. To date, there is no recommended interpolation method when the study extent is circular with well-distributed points – the core objective of this research is oriented towards this. An attempt was made to generate a digital bathymetric surface for the Mauritius coast with ∼ 1.2 million depth points accrued from the NASA ICESat-2 geolocated photons and sounding depths from the marine charts. These points were used as input to interpolation methods like Inverse Distance Weighted, Natural Neighbour, and various forms of Ordinary Kriging. Our findings show that all the methods have generated visually similar surfaces, but the Inverse Distance Weighted interpolation has given the output with less quantified uncertainty

New data on the structure of the Laptev Sea flank of the gakkel ridge (Arctic Ocean)

The article provides new data on the structure of the Laptev Sea flank of the Gakkel Ridge. The intensive supply of clastic material from the shelf of the Laptev Sea leads to the development of a thick alluvial cone at the continental foot, which determines the structure of the bottom topography. In the northwestern direction, the influence of the fan decreases and tectonics becomes the main relief-forming factor. The bathymetric survey traced the asymmetrical rift valley of the Gakkel Ridge, the western side of which is complicated by terraces. The presence of fault structures, bottom subsidence and intensive sediment supply, and the widespread development of landslide processes indicate high neotectonic activity of the Laptev Sea flank of the Gakkel Ridge. For the first time in this region, numerous carbonate formations have been discovered, the authigenic cement of which is represented by magnesian calcite or aragonite with an admixture of terrigenous material. Palynological and micropaleontological analysis of carbonate formations indicates the Quaternary formation of authigenic carbonate cement. An important role in the formation of authigenic carbonates was played by diagenetic solutions coming from the sedimentary cover together with methane and products of oxidation of gases and organic matter. Authigenic carbonates were deposited mainly in isotopic equilibrium with bottom water at a temperature of about 0°C. The negative correlation between 87Sr/86Sr and δ13C indicates the presence of at least two different sources of carbonate-forming solutions.

Detecting submarine landslides caused by the 2024 Noto Peninsula Earthquake through repeat bathymetric surveys in Toyama Bay, Japan

On January 1, 2024, an earthquake of magnitude 7.6 struck the Noto Peninsula in Ishikawa Prefecture, Japan. Tsunamis were recorded along nearby coasts following the earthquake, with the early tsunami arrival time at the Toyama tide station—located far from the earthquake epicenter—indicating potential submarine landslides in Toyama Bay. To identify these potential submarine landslides by detecting changes in seafloor depth, we collected new bathymetric data using a multibeam echo sounder in January and February 2024, and then compared them with data collected in 2010. This bathymetric comparison revealed submarine landslides along a submarine canyon off the Jinzu River, covering an area measuring 3.5 km × 1 km at depths of 40–370 m. Slide relief ranged from several meters up to 40 m, with some slides displaying distinct head scarps. Seafloor observations in areas with minor depth changes confirmed the presence of cliffs, disturbed seabed, and a redox boundary on the disturbed oxide layer, indicating recent landslides. Given the slide distribution within the estimated tsunami source area of the 2024 Noto Peninsula Earthquake, it is likely these slides were triggered by the earthquake.

Tectonic anabranching of Brahmaputra River system: implications on survival of world’s largest inhabited river island Majuli

Brahmaputra is a large, tropical, trans-boundary river with high sediment load and has the unique distinction of possessing both largest and smallest inhabited river islands. Majuli is the largest inhabited river island situated in the Indian state of Assam and bounded by Brahmaputra on the south, Subansiri River on the northwest, and the Kherkatia River (anabranch of Brahmaputra) on the northeast. The island was formed during a flooding event in 1750 with a sudden change in the course of the Brahmaputra from a low energy meandering to a high energy braided river and subsequent capture of one of its tributaries. The island is a part of the Brahmaputra alluvium squeezed between active Himalayan and Indo-Burmese orogenic belts in an intricate tectonic regime. The dominant flow path of Brahmaputra is controlled by the crustal scale reorganization in this part of the world. The tectonic factors that controlled the anabranching process and created the island, is at present acting as the destroyer of the same by the means of unabated erosion. The erosion pattern of the two rivers viz. Brahmaputra and Subansiri were studied and areas with marked selective erosion have been found. From a combined study of satellite imaging, bathymetric survey and mapping, it is found that the lobate shaped erosions in the study areas are restricted to traces of the tectonic elements related to the Himalayan thrust system through which the rivers are trying to anabranch.

Comparison of multitemporal multifrequency multibeam echosounder norbit iwbms: depth and sedimentation rate analysis of selorejo reservoir 2022-2023

Abstract Selorejo Reservoir is a reservoir constructed and located in Pandansari Village, Ngantang District, Malang Regency, East Java. The Indonesian Government built this reservoir to accommodate the water flow from several rivers, including the Konto River, Kletak Lahar, Kwayangan River, and several other small rivers. The biggest challenge for a reservoir, where the primary clean water source comes directly from rivers, is siltation caused by sediment accumulation at the bottom of the water body. Therefore, severe and continuous control in the reservoir area is necessary to prevent damage and overflow and ensure the community’s safety by engaging in activities around the Selorejo Reservoir. Bathymetric surveys are essential in obtaining information related to marine fields and precise depth values with spatial references. When using a multibeam echosounder, surveyors must consider several aspects regarding the specifications of the equipment before data acquisition, one of which is the frequency used. Different frequencies result in different penetration abilities and data quality. This study aims to estimate the sedimentation rate in the Selorejo Reservoir using multitemporal data and investigate the effect of using multifrequency on the depth measurement results obtained. The results of this study indicate that the higher the frequency used, the shallower the depth value obtained. Higher frequencies provide better representation in object detection capabilities. At the same time, the sedimentation rate was relatively high, from 3.2 to 5.3 centimetres per month.

Estimation of Sound Speed Profile at Southbound of South China Sea For Bathymetric Survey Using Machine Learning

Estimation of Sound Speed Profile at Southbound of South China Sea For Bathymetric Survey Using Machine Learning

Spatial and Temporal Distribution of Habitat Pattern of Trichiurus japonicus in the Northern South China Sea Under Future Climate Scenarios

The impact of climate change on fish distribution has drawn increasing attention worldwide. Studying the distribution patterns and habitat evolution trends of largehead hairtail (Trichiurus japonicus), an important fishery resource in the northern South China Sea (NSCS), is of great significance for the management and sustainable utilization of fishery resources. This study uses an ensemble species distribution model to analyze the seasonal distribution patterns of T. japonicus in the NSCS and predict the changes in highly suitable habitats of T. japonicus under four future climate scenarios (IPCC Shared Socioeconomic Pathways SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). The results show that the area of suitable habitats in the Beibu Gulf is expected to increase, while that in the offshore of Guangdong will significantly decrease. In different seasons, there are differences in environmental factors affecting the distribution of T. japonicus, among which sea bottom temperature (SBT) and bathymetry (BM) are key factors. Under the SSP1-2.6 scenario, the area of highly suitable habitats for T. japonicus is expected to decrease by 30.54% by the 2100s, while under the SSP5-8.5 scenario, it is expected to decrease by 53.67%. Our research results show that the active range of T. japonicus in the NSCS has different adaptive responses to different climate change scenarios, which has an important impact on the development and management of T. japonicus resources.

Analyzing Depth Uncertainty of Near-Shore Bathymetric Survey Conducted by Single-Beam Echo Sounder

Single-beam echo sounders have gained popularity for various applications due to their compact dimensions, ease of use, and cost-effectiveness. The question that often arises among the users is whether these devices can fulfill the necessary accuracy requirements. This paper concentrates on assessing the accuracy that can be achieved using a single-beam echo sounder. An accuracy assessment was performed by comparing the depths derived from the 3D model created from the single-beam echo sounder data to those obtained through more accurate and independent method (tacheometric surveying) in the test area. Accurate depth determination was achieved through trigonometric leveling, employing a specific methodology that allows for precise depth measurements up to 4.5 meters. The assessment results were compared to the vertical accuracy requirements for surveying and mapping in shallow waters, recommended by the International Hydrographic Organization. The results indicate that, with a 95% probability, the depths determined by the single-beam echo sounder meet the total vertical uncertainty (TVU) requirements specified by the S-44 standard for Order 1a survey.

Analysis of suspended sediment concentration characteristics under erosion-deposition condition changes in the Yangtze River Estuary

In recent years, as river-borne sediment transport has decreased, land loss in estuarine areas has become increasingly severe. Particularly from 2009 to 2022, due to the reduced sediment load from the upper reaches of the Yangtze River, significant changes in the erosion-deposition conditions at the Yangtze River Estuary have become a critical concern. The suspended sediment concentration (SSC) in the estuary is closely linked to sediment content, and against this backdrop, this study aims to thoroughly explore the response mechanisms of the Yangtze River Estuary’s SSC to changes in erosion-deposition conditions, with the goal of providing scientific bases and strategic recommendations for erosion-deposition management. To this end, this research collected historical water depth data for the Yangtze River Estuary, measured vertical distribution of SSC in September 2022, surface suspended sediment concentration (SSSC) data from 2021 to 2023, and 25 factors influencing SSSC, to analyze in detail the changes in the erosion-deposition conditions at the Yangtze River Estuary and the response mechanisms of SSC to these changes. The analysis showed that between 2009 and 2022, the mouth bar area of the Yangtze River Estuary experienced net erosion for the first time since 1958, with an annual erosion rate reaching 63.2 × 10^6 m3/yr, and the highest erosion rate occurring in the North Passage area, reaching 83.3 mm/yr. This phenomenon is likely caused by human-induced changes in underwater topography, with the Yangtze River Estuary shifting from deposition to erosion. Between 2021 and 2023, the turbidity maximum zone (TMZ) of the Yangtze River Estuary did not show regular changes in SSSC, which may be related to the frequent occurrence of typhoons and changes in sediment supply in the submerged delta of the Yangtze River Estuary.

Evidence of a pelagic nursery area for phyllosomas of the scyllarid lobster Acantharctus ornatus (Holthuis, 1960) (Decapoda: Achelata: Scyllaridae) in a coastal bight in South Africa

Abstract Lobster phyllosoma larvae collected during surveys over the continental shelf of eastern South Africa (southwestern Indian Ocean) were analysed to determine the role of the KwaZulu-Natal (KZN) Bight as a pelagic nursery area. Surface waters in the shallow bight and further offshore, between the 20- and 1,000-m depth contours, were sampled with plankton nets in 2018 to 2023. Phyllosomas were absent from 87.9% of 257 tows, with high variability in the remaining tows indicating a patchy distribution with abundance hotspots. Phyllosomas of four scyllarid and three palinurid species were found among 311 captured specimens. The scyllarid Acantharctus ornatus (Holthuis, 1960) was the most abundant, constituting 94.9% of the phyllosomas caught, with all nine larval stages (I–IX) present. Phylogenetic analysis using the COI and 16S rDNA gene markers confirmed that previously undescribed early larval stages in samples belonged to A. ornatus. Most A. ornatus phyllosomas were caught at shallow-bight stations, with catch rates declining steeply to the north and south of the bight and when bottom depth exceeded 100 m. Season and sampling station (nested within cross-shelf transect) were significant variables in explaining phyllosoma abundance. We provide evidence that the KZN Bight serves as a pelagic nursery area for A. ornatus phyllosoma larvae at all developmental stages, but not for other lobster species with known adult populations in the region.

Comparison of GIS-based solutions for the assessment of lakes water volume: a case study of biosphere reserve "Shatskyi"

Understanding the volume of water in a lake is essential for assessing the health of the eco-system. Geographic Information Systems offer valuable tools for evaluating water volume in lakes, employing such methods as remote sensing for surface data and bathymetric surveys for lakebed data. By integrating techniques like sonar-based bathymetric surveys, precise depth measurements can be obtained to accurately calculate water volume. Based on the survey results, depth maps of three lakes of different sizes, depths, and origins within the Biosphere Reserve were created. Key morphometric characteristics and the volume of water mass were calculated from these surveys. However, it is important to note that these investigations can be expensive and time-consuming, especially for large lakes. It may not be feasible for lakes in remote or inaccessible areas. Hollister JW's (2010) bathymetry modelling method was applied, as an alternative to ground-based bathymetry survey results, to calculate the water volume of the above-mentioned lakes. The method is based on the assumption that the depth of the reservoir is a function of distance from the shoreline. The advantage of the method is the limited amount of input data, namely the area and maximum depth of the reservoir. The modeling bathymetry method is not suitable for very deep lakes like Svitiaz Lake, with complicated lake basin shapes, as demonstrated by comparing the results with ground-based bathymetric survey data. The lake with the smallest depth and more regular lake basin form, which is closer to a circular shape, such as Liutzimer Lake, provided the best results. Using the bathymetric modelling approach for other medium and small Bioreserve lakes could help to define the characteristics of water bodies for which this method can be extremely useful.

Sedimentary and geomorphological evolution of a young tidal flat in the northern part of the Po delta (Italy)

Due to anthropic activities of the last centuries, coastal wetlands worldwide lost wide portions of salt marshes. Since these ecosystems provide fundamental services and benefits to both natural and anthropic components, the natural restoration of these habitats is becoming one of the main objectives of these days, and the opening of new connections between land and sea is becoming a highly used technique to restore portions of intertidal areas. According to recent studies based on analysis of long-term satellite imagery datasets and bathymetric surveys, the Po River Delta (Northern Italy) is currently subjected to a positive sedimentation trend and a constructive process is ongoing at the main river branches. Following an evolution similar to restoration projects, new tidal flats are building up around the tip of the delta, where agricultural fields were inundated by strong floods in the 1950s and the 1960s. This study focuses on a young tidal flat of about 8 ha, located in the Southernmost part of the Barbamarco lagoon. Sediment granulometric distribution and sedimentary pattern were investigated between May 2019 and March 2021 through coring, sediment traps, and orthophotos. The results show that the system is undergoing a progradation and an extended crevasse splay is developing. This covers the central part of the flat and it has developed from the early 2000s, due to human intervention on levees as well as river floods. The levees of the eastern channel stabilized between 2008 and 2012 thanks to vegetation growth, allowing the floods to focus in the NW direction, leading to the development of this recent feature. The presence of the crevasse splay confirms the importance of the river floods on the tidal flat formation. The calculated depositional rates suggest that sedimentation is higher during summer (average 66.89 g/m2 per submersion event) and lower during winter (18.86–20.65 g/m2 per submersion event). These trends are opposite to the seasonal trends observed in the literature, showing that the deposition controlled by the tide is lower compared to the river influence and suggesting that the river is the dominant factor.

Constructing a 22-year internal wave dataset for the northern South China Sea: spatiotemporal analysis using MODIS imagery and deep learning

Abstract. Internal waves (IWs) are an important ocean phenomenon facilitating energy transfer between multiscale ocean processes. Understanding such processes necessitates the collection and analysis of extensive observational data. IWs predominantly occur in marginal seas, with the South China Sea (SCS) being one of the most active regions, characterized by frequent and large-amplitude IW activities. In this study, we present a comprehensive IW dataset for the northern SCS (https://doi.org/10.12157/IOCAS.20240409.001, Zhang and Li, 2024), covering the area from 112.40 to 121.32° E and from 18.32 to 23.19° N, spanning the period from 2000 to 2022 with a 250 m spatial resolution. During the 22 years, a total of 15 830 MODIS images were downloaded for further processing. Out of these, 3085 high-resolution MODIS true-color images were identified to contain IW information and were included in the dataset with precise IW positions extracted using advanced deep learning techniques. IWs in the northern SCS are categorized into four regions based on extracted IW spatial distributions. This classification enables detailed analyses of IW characteristics, including their spatial and temporal distributions across the entire northern SCS and its specific sub-regions. Interestingly, our temporal analysis reveals characteristic “double-peak” patterns aligned with the lunar day, highlighting the strong connection between IWs and tidal cycles. Furthermore, our spatial analysis identifies two IW quiescent zones within the IW clusters influenced by underwater topography, highlighting regional variations in IW characteristics and suggesting underlying mechanisms which merit further investigation. There are also three gap regions between distinct IW clusters, which may indicate different IW sources. The constructed dataset holds significant potential for studying IW–environment interactions, developing monitoring and prediction models, validating numerical simulations, and serving as an educational resource to promote awareness and interest in IW research.

A comprehensive analysis of reservoir capacity loss: a case study of the Akhangaran Reservoir, Uzbekistan.

The purpose of this article is to analyze the loss of capacity in the Akhangaron reservoir due to sedimentation processes. With the reservoir having been in operation for 50 years, understanding the dynamics of its water reserves is crucial, especially considering the impact of siltation on its volume and functionality. Through detailed analysis, including bathymetric surveys and geostatistical methods, this study aims to assess the current state of the reservoir volume, identify trends in volume loss over time, and predict future capacity reductions. By providing valuable insights into sediment dynamics and reservoir capacity loss, the findings of this study seek to inform and guide future management strategies for the Akhangaron reservoir and similar water management systems. The obtained results showed that the analysis of the Akhangaron reservoir from 1972 to 2022 reveals significant volume losses, with a total reduction of 28.6 Mm3 (14.44%), impacting both useful and dead volumes, demonstrated by a decrease in useful volume by 21.3 Mm3 (11.52%) and a significant decrease in dead volume by 7.3 Mm3 (55.73%). Additionally, surface area reductions at both full storage level (FSL) and dead storage level (DSL) underscore sedimentation's impact, particularly evident at lower water levels. The projections indicate significant declines in both total and useful volumes, essential for water supply and operational efficiency. By 2072, the total volume is expected to decrease by 39.45%, while the useful volume is anticipated to drop by 36.45% over the same period. Of particular concern is the predicted reduction in the dead volume, crucial for sediment storage. By 2044, projections suggest that 82.28% of the dead volume will be lost, and by 2062, the dead volume is forecasted to be completely silted (100% loss), rendering the reservoir's regulating capacity unmanageable.

Coastline Bathymetry Retrieval Based on the Combination of LiDAR and Remote Sensing Camera

This paper presents a Compact Integrated Water–Land Survey System (CIWS), which combines a remote sensing camera and a LiDAR module, and proposes an innovative underwater topography retrieval technique based on this system. This technique utilizes high-precision water depth points obtained from LiDAR measurements as control points, and integrating them with the grayscale values from aerial photogrammetry images to construct a bathymetry retrieval model. This model can achieve large-scale bathymetric retrieval in shallow waters. Calibration of the UAV-mounted LiDAR system was conducted using laboratory and Dongjiang Bay marine calibration fields, with the results showing a laser depth measurement accuracy of up to 10 cm. Experimental tests near Miaowan Island demonstrated the generation of high-precision 3D seabed topographic maps for the South China Sea area using LiDAR depth data and remote sensing images. The study validates the feasibility and accuracy of this integrated scanning method for producing detailed 3D seabed topography models.