Channel Deepening Research Articles

Analysis of Navigation Aid Effectiveness of Tianjin Port Water Depth Signal Tower and Development Protection under New Technical Conditions

The Tianjin Port Water Depth Signal Tower is a navigational aid facility that provides tidal level information. In the last century, it made great contributions to the shipping industry of Tianjin Port and played an indispensable role in local flood control work; However, with the improvement of the accuracy of marine radar sounders, the influence of background lights, the increase of surrounding buildings, and the continuous widening and deepening of navigation channels, it is becoming increasingly rare for ship drivers to obtain tidal level information through their eyes or with the help of telescopes. In addition, whether drivers can obtain tidal level information through these methods is also a topic worthy of attention and research.

Morphological Response of a Highly Engineered Estuary to Altering Channel Depth and Restoring Wetlands

Estuaries are continuously adapting to anthropogenic pressure. Because of sea-level rise and reduced fluvial sediment supply, they are at risk of sediment starvation. Contrarily, some estuaries require frequent dredging after artificially deepening the channel to maintain port operations. To optimize current estuarine functions and make estuaries more resilient to future threats, improved understanding of estuarine development after system changes is essential. This paper investigates the estuarine response related to two large-scale human interventions: (1) altering channel depth, following global trends of channel deepening for port navigability; and (2) creating or restoring wetlands, a nature-based solution increasingly explored for its ecosystem services. A schematized 2D-morphological model is set up using Delft3D-FM reflecting a highly engineered estuary in a micro-tidal and wave-dominant environment. Results demonstrate how channel deepening (from 13 m to 17 m, without wetland presence) increased sedimentation in the channel by +31%. Sedimentation rates in the wetland were mostly unaffected by channel depth. After restoring the wetland area (wetland width from 0 km to 1 km, constant channel depth of 15 m), sedimentation within the channel was reduced by −72%. The wetland area not only served as sediment sink, but also increased the tidal flow, diminishing sedimentation throughout the estuarine channel. Further analysis showed that restoring wetland areas along a specific segment mostly affected channel sedimentation locally (i.e., at the channel segment along the restored wetland). As such, to alleviate dredging operations at critical locations in the navigation channel, strategic restoration of wetlands can be considered which can provide a sustainable alternative to dredging within highly engineered estuaries.

BENEFICIAL USE OF DREDGED MATERIAL AND FATE OF PLACED SAND USING A HYBRID COSMOS-XBEACH SEDIMENT BUDGET MODEL

The Corpus Christi Ship Channel in Texas connects the Port of Corpus Christi to the Gulf of Mexico. The Port is seeking to deepen the channel to allow fully loaded very large crude carriers to access proposed terminals within the port complex. Dredge material from the channel deepening is to be used as beach nourishment and to create offshore berms along Mustang Island and San Jose Island. The fate of the beach nourishment and offshore berms was assessed using the Hybrid C-X (COSMOSXBeach) Sediment Budget Model. Longshore and cross-shore transport processes were incorporated in the model using COSMOS (longshore) and XBeach (cross-shore) models. Multi-year simulation of the fate of placed material using process-based twodimensional horizontal (2DH) models requires long CPU times which are often impractical. A hybrid sediment budget model using process-based crossshore profile models was thus developed.

MORPHOLOGICAL CHANGES TO THE PORTSEA (VICTORA) COASTLINE FOLLOWING SHIPPING CHANNEL DEEPENING

Portsea Beach is located on the south side of Port Phillip Bay approximately 55 km south of Melbourne and 6 km east of Point Nepean at the Entrance to the Bay. Portsea Beach experienced significant erosion in 2009 and 2010. The erosion occurred shortly after the dredging that was carried out as part of the Port of Melbourne’s “Channel Deepening Project” to deepen the shipping channel that provides access to the Port of Melbourne. The erosion at Portsea did not occur in isolation. Since 2009, there has also been significant on-going erosion along Nepean Bay Beach to the west, and significant accretion along Shelley Beach and Point King Beach to the east.

CORPUS CHRISTI SHIP CHANNEL DEEPENING PROJECT: OVERVIEW and MODELING APPROACH TO ASSESS ENVIRONMENTAL IMPACTS

The Corpus Christi Ship Channel in Texas connects the Port of Corpus Christi to the Gulf of Mexico. The Port is seeking to deepen the Corpus Christi Ship Channel to 22.9m (75ft) nominal depth in order to allow fully loaded very large crude carriers (VLCC’s) to access proposed terminals within the port complex. As a part of the environmental coordination requirements of the National Environmental Policy Act (NEPA) the Port Authority prepared a number of studies to assess the potential environmental impacts of the proposed channel deepening. These included assessing changes in hydrodynamics, salinity, storm surge, and sedimentation patterns including sediment movement generated by vessel generated currents. The channel design was also verified through vessel maneuvering studies which were conducted using modeled currents, dynamic underkeel clearance assessment, and propeller scour potential determination. The fate of proposed beneficial use of dredged materials to construct a submerged beach berm and perform beach nourishment was also assessed.

BLUE LINES AS A MEANS OF GRAPHIC FIXATION BETWEEN WATER BODIES IN TOWN PLANNING DOCUMENTATION

In this article the purpose of the Blue Lines of Limitation as a fixation of the spatial boundaries of water bodies in the urban planning activity is considered. The peculiarities and importance of the use of Blue Lines as boundaries of the water area for maintaining urban planning discipline are indicated. Preservation of the boundaries of water areas in an urbanized environment requires the introduction of a separate urban planning restriction in the urban planning documentation. Along with the Red, Blue, Green and Yellow lines, which are already "working" in urban planning documentation, the Blue lines will graphically display the borders of the water area, regulating the regulation of urban planning activities in certain territories, which will contribute to urban planning discipline and the preservation of water ecosystems.
 Blue lines can graphically fix the boundaries of the water area to limit urban planning and economic activity. Our proposal is to introduce the concept of Blue Lines into the new edition of DBN B2.2-12-202… «Planning and Development of Territories» in the following wording: "Boundaries of the coastline (cut of water) on the natural or artificially created water area of water bodies (reservoirs and water courses) - the internal boundaries of the water protection zone with defined regimes and rules of economic activity are defined by blue lines."
 The development of district planning schemes, general plans of settlements, detailed plans of the territory (M 1: 25000, 1:10000, 1: 2000) graphically, with the help of blue lines, should indicate:
 - cuttings of existing and artificially created reservoirs; - section of direction, channel deepening; - changing the contour of reservoirs in case of their revitalization, etc.
 Fixing the spatial boundaries of the water area with the help of Blue lines will fulfill the tasks of urban planning regulations of economic activity, which will contribute to the preservation of the natural component of the water ecosystem in an urbanized environment.
 To preserve and protect water bodies in an urbanized environment, effective urban planning restrictions are necessary. Urban planning restrictions contribute to the preservation of our settlements from chaotic and disharmonious construction, make the urban space safe and comfortable for residents. The designation of the Blue Lines is a tool for preserving the natural component in the urbanized environment, which will help solve the problem of balanced, rational and harmonious use of water areas and vulnerable coastal areas.

Detailed modelling to evaluate the effectiveness of sediment recycling on coastal habitat

In many parts of the world, ports and harbours lie adjacent to ecologically important areas of coastal habitat. In such areas port authorities, coastal managers and regulators are required to negotiate the tension between the demands of making ports ever more efficient, with wider and deeper approaches to accommodate vessels of deeper draft and larger handling areas, and the preservation of coastal habitats which are vitally important for bird and fish populations and which help protect the coast from flooding and erosion. The deepening of approach channels and berths usually results in an increased rate of sedimentation and maintenance dredging. There is an increasing recognition that such dredged sediment is a resource which should be utilised beneficially for human development activities and/or enhancement of ecological habitats. One form of beneficial use of dredged material, is termed “sediment recycling” or “strategic placement”. This form of beneficial use consists of the placement of cohesive sediment into the water column or onto the bed in such a way so that currents and waves then transport the released sediment onto the desired habitats. Sediment recycling is less widely practiced because the changes in bed level resulting from placement are generally of the order of a few centimetres/year or less and it is difficult to demonstrate whether such recycling is successful. This paper describes a methodology for the assessment of the effectiveness sediment recycling, implementing the methodology on a case study of a large-scale sediment recycling scheme in the Stour/Orwell Estuary system in the United Kingdom, designed to offset the identified adverse effects of an approach channel deepening on the estuary system. The study represents a major contribution to the consideration of non-direct beneficial use of cohesive sediment. For the first time a methodology for reliably evaluating the effects of sediment recycling, separating the effects of natural changes in morphology from the beneficial use, has been shown to be effective. This method, which is applicable anywhere where there are sufficient data, allows a robust evaluation of the effectiveness of such methods and crucially enables these methods to be tested and optimised using modelling before implementation.

Effect of Sea Level Rise and Access Channel Deepening on Future Tidal Power Plants in Buenaventura Colombia

The evolution of tidal stream turbines is increasing the feasibility of future tidal plants in shallow depth areas with mid-tidal ranges (<5 m). However, extreme events such as changes in bathymetry due to the access channel deepening of coastal ports and sea level rise modify hydrodynamics and might affect the infrastructure and energy production of tidal energy converters. This research focused on Buenaventura Bay to analyze the effect of these extreme events on marine currents through calibrated-validated numerical modeling. Several monitored points were analyzed, and the results highlighted that the bay has potential for implementing tidal stream turbines because of the reported velocities between 0.25 and 2 m/s. The sea level rise increased 11.39% and access channel deepening reduced by 17.12% the velocity currents of the bay, respectively. These findings convert Buenaventura Bay to a candidate for implementing third generation tidal stream turbines and motivate future research for implementing tidal power systems in crucial areas such as the Colombian Pacific, where communities face restrictions in accessing affordable and clean energy.

Estuarine response to storm surge and sea-level rise associated with channel deepening: a flood vulnerability assessment of southwest Louisiana, USA

This study investigates the sensitivity of the Calcasieu Lake estuarine region to channel deepening in southwest Louisiana in the USA. We test the hypothesis that the depth increase in a navigational channel in an estuarine region results in the amplification of the inland penetration of storm surge, thereby increasing the flood vulnerability of the region. We run numerical experiments using the Delft3D modeling suite (validated with observational data) with different historic channel depth scenarios. Model results show that channel deepening facilitates increased water movement into the lake–estuary system during a storm surge event. The inland peak water level increases by 37% in the presence of the deepest channel. Moreover, the peak volumetric flow rate increases by 291.6% along the navigational channel. Furthermore, the tidal prism and the volume of surge prism passing through the channel inlet increase by 487% and 153.3%, respectively. In our study, the presence of the deepest channel results in extra 56.72 km2 of flooded area (approximately 12% increase) which is an indication that channel deepening over the years has rendered the region more vulnerable to hurricane-induced flooding. The study also analyzes the impact of channel deepening on storm surge in estuaries under different future sea-level rise (SLR) scenarios. Simulations suggest that even the most conservative scenario of SLR will cause an approximately 51% increase in flooded area in the presence of the deepest ship channel, thereby suggesting that rising sea level will cause increased surge penetration and increased flood risk.

Adaptation timescales of estuarine systems to human interventions

Many estuaries and tidal basins are strongly influenced by various human interventions (land reclamations, infrastructure development, channel deepening, dredging and disposal of sediments). Such interventions lead to a range of hydrodynamic and morphological responses (a changing channel depth, tidal amplitude and/or suspended sediment concentration). The response time of a system to interventions is determined by the processes driving this change, the size of the system, and the magnitude of the intervention. A quantitative understanding of the response time to an intervention therefore provides important insight into the processes driving the response. In this paper we develop and apply a methodology to estimate the response timescales of human interventions using available morphological and hydraulic data. Fitting an exponential decay function to data with sufficient temporal resolution yields an adaptation timescale (and equilibrium value) of the tidal range and deposited sediment volumes. The method has been applied in the Dutch Wadden Sea, where two large basins were reclaimed and where long-term and detailed bathymetric maps are available. Exponential fitting the morphological data revealed that closure of a very large part of a tidal basin in the Wadden Sea initially led to internal redistribution and import of coarse and fine sediments, and was followed by a phase of extensive redistribution while only fine-grained sediments are imported. Closure of a smaller part of a smaller basin led to shorter response timescales, and these response timescales are also more sensitive to rising mean sea levels or high waters. The method has also been applied to tidal water level observations in the Scheldt and Ems estuaries. Exponential fits to tidal data reveal that adaptation timescales are shortest at the landward limit of dredging. The adaptation time increases in the landward direction because of retrogressive erosion (Scheldt) or lowering of the hydraulic roughness (Ems). The seaward increase in adaptation time is related to the seaward widening of both systems.

Effect of Estuary Urbanization on Tidal Dynamics and High Tide Flooding in a Coastal Lagoon

AbstractHigh tide floods (HTFs) are minor, shallow flooding events whose frequency has increased due to relative sea‐level rise (SLR) and secular changes in tides. Here we isolate and examine the role of historical landscape change (geomorphology, land cover) and SLR on tides and HTF frequency in an urbanized lagoonal estuary: Jamaica Bay, New York. The approach involves data archeology, historical (1870s) map digitization, as well as numerical modeling of the bay. Numerical simulations indicate that a century of landscape alterations (e.g., inlet deepening and widening, channel deepening, and wetland reclamation) increased the mean tidal range at the head of the bay by about 20%. The observed historical shift from the attenuation to amplification of semidiurnal tides is primarily associated with reduced tidal damping at the inlet and increased tidal reflection. The 18% decrease in surface area exerts a minor influence. A 1‐year (2020) water level simulation is used to evaluate the effects of both SLR and altered morphology on the annual number of HTFs. Results show that of 15 “minor flood” events in 2020, only one would have occurred without SLR and two without landscape changes since the 1870s. Spectral and transfer function analyses of water level reveal frequency‐dependent fingerprints of landscape change, with a significant decrease in damping for high‐frequency surges and tides (6–18 hr time scale). By contrast, SLR produced only minor effects on frequency‐dependent amplification. Nonetheless, the geomorphic influence on the dynamical response significantly increases the vulnerability of the system to SLR, particularly high‐tide flooding.

Large-scale morphological changes and sediment budget of the Western Scheldt estuary 1955–2020: the impact of large-scale sediment management

Abstract In the Western Scheldt estuary, like in many estuaries, safe navigation, flood protection, and ecological targets require a balanced and sustainable sediment management. A thorough understanding of the morphodynamic functioning of the estuary and its response to changes in hydrodynamics (natural sediment transport) and large-scale interventions is imperative. This paper presents a detailed overview of over 65 years of morphological changes and a comprehensive sediment budget of the Western Scheldt estuary that is based on analysis of a unique series of frequent bathymetric surveys and historical data on human–sediment interactions of dredging, dredge disposal and sand mining. Solving the sediment budget reveals an annual sediment import of 2.2 million m3. The highest sediment imports occurred between 1980–1994 and 2005–2020 (2.9 and 3.7 million m3/year). A 1.3 million m3/year net export prevailed between 1994 and 2005. Natural variations in the hydrodynamics (e.g., tidal asymmetry and amplification) and sediment transports cannot explain the derived temporal variations in sediment import rates. Anthropogenic activities play a dominant role. Capital dredging of the main navigation channel has led to channel deepening and significantly increased dredge and disposal volumes. Disposal on tidal flats and in the secondary channel leads to a long-term storage of sand and, consequently, a local increase in bed level and a sand deficit in the remainder of the system that results in increased sediment imports. Large-scale disposal in the western part of the estuary can (temporarily) reverse the sediment exchange between the estuary and its mouth area, as observed between 1994 and 2005. Apparently, large-scale anthropogenic reallocation of sediment by dredging and/or disposal as part of navigation channel improvement, sand mining or nourishment essentially influences the morphological development of the Western Scheldt estuary. This reveals responsibilities as well as opportunities of sediment management for the Western Scheldt and similar estuaries worldwide.

A Novel Visualisation Tool for Reliable Inland Navigation

Within this paper, we present a novel visualisation tool for inland navigation. The main contributions of the tool are that (a) water levels of rivers can be compared on a yearly basis, (b) infrastructural measures (e.g., fairway channel deepening) and their impacts on the water levels can be easily evaluated, (c) single trip planning for captains is eased as water level conditions along the trips are considered, and (d) evaluations of shipping strategies can be easily evaluated (and accordingly adjusted). For this purpose, data has been collected on the Danube River for five consecutive years and for eight critical bottlenecks. Based on this data, the visualisation has been developed.

The influence of dredging on estuarine hydrodynamics: Historical evolution of the Santos estuarine system, Brazil

We assess changes in estuarine hydrodynamics due to the deepening of navigation channels by dredging. A validated numerical hydrodynamic model (Delft3D) was used to analyze scenarios (historical bathymetry data from 1876 to 2014) and applied to assess the hydrodynamic evolution of the Santos estuarine system (SES), Brazil. During the studied period, the SES underwent significant morphological changes, mainly related to the dredging of the Santos harbor navigation channel. The unprecedented results of the hydrodynamic evolution of the SES show that the gradual process of deepening the channels by dredging resulted in modified estuarine circulation parameters such as tidal propagation and stratification of the water column, as well as the residual water and materials transport through the SES channels. Channel deepening resulted in greater saline intrusion, a decrease in the volume of water transported through the Santos channel, an increase in the influence of the tide in the system and an increase in its asymmetry over the years in the upper estuary.

Sustainable Development of Coastal Areas: Port Expansion with Small Impacts on Estuarine Hydrodynamics and Sediment Transport Pattern

With the expansion of global trade and the growing traffic of increasingly larger ships to meet this demand, the need to expand port infrastructure appears as the main alternative. In this way, dredging operations for the maintenance and deepening of navigation channels, as well as the expansion of evolution basins and berthing wharf areas become fundamental, generating large amounts of material removed from the bottom. Aiming at port expansion based on a sustainable development and minimization of the environmental impacts generated by these operations, it is necessary to seek alternatives for the destination of large volumes of dredged material. A sustainable alternative is to dispose these volumes on land in order to expand coastal areas (such as fattening beaches) and mooring pier areas. The present work presents a numerical modeling case study using the TELEMAC-3D model coupled to the suspended sediment module SEDI-3D. As an alternative, an existing island (Ilha do Terrapleno) will receive material dredged from the access channel to the Port of Rio Grande (southern Brazil) and will have its mooring area expanded. The study evaluated the impact that this change in the island’s configuration would generate on the hydrodynamics and on the deposition patterns of fine suspended sediments in its surroundings and in the adjacent navigation channel. Results indicated that in the navigation channel adjacent to Ilha do Terrapleno, the new configuration promoted changes in the hydrodynamics with a decrease in the mean current velocity around the island and throughout the water column, mainly in the north and central portions of the channel. This difference decreased towards the southern portion of the channel. This change in local hydrodynamics promoted small changes in the suspended sediment deposition patterns and in the bottom evolution. Thus, the sustainable expansion of the Port of Rio Grande operational capacity considering the creation of 3600 m of berthing wharf areas and minimum environmental impact proved viable when considering the Ilha do Terrapleno proposed configuration. Furthermore, this idea offers the possibility to dispose in land 722,910 m3 of dredged material, a sustainable alternative to the Port of Rio Grande development, and an inspiration for the sustainable development of other ports worldwide.

Development History of the Numerical Simulation of Tides in the East Asian Marginal Seas: An Overview

As a ubiquitous movement in the ocean, tides are vital for marine life and numerous marine activities such as fishing and ocean engineering. Tidal dynamics are complicated in the East Asian marginal seas (EAMS) due to changing complex topography and coastlines related to human activities (e.g., land reclamation and channel deepening) and natural variability (e.g., seasonal variations of ocean stratification and river flow). As an important tool, numerical models are widely used because they can provide basin-scale patterns of tidal dynamics compared to point-based tide gauges. This paper aims to overview the development history of the numerical simulation of tides in the EAMS, including the Bohai Sea, the Yellow Sea, the East China Sea, the East/Japan Sea, and the South China Sea, provide comprehensive understanding of tidal dynamics, and address contemporary research challenges. The basic features of major tidal constituents obtained by tidal models are reviewed, and the progress in the inversion of spatially and temporally changing model parameters via the adjoint method are presented. We review numerical research on how a changing ocean environment induces tidal evolution and how tides and tidal mixing influence ocean environment in turn. The generation, propagation, and dissipation of internal tides in the EAMS are also reviewed. Although remarkable progresses in tidal dynamics have been made, nonstationary tidal variations are not fully explained yet, and further efforts are needed. In addition, tidal influences on ocean environment still receive limited attention, which deserves special attention.

Responses of estuarine circulation to the morphological evolution in a convergent, microtidal estuary

Abstract. The Huangmaohai estuary (HE) is a funnel-shaped microtidal estuary in the west of the Pearl River Delta (PRD) in southern China. Since China reformed and opened up in 1978, extensive human activities have occurred and greatly changed the estuary's topography and modified its hydrodynamics. In this study, we examined the morphological evolution by analyzing remote sensing data with ArcGIS tools and studied the responses of hydrodynamics to the changes in topography from 1977 to 2010 by using the Delft3D model. We took the changes in estuarine circulation during neap tides in dry seasons as an example. The results show that human reclamation caused a narrowing of the estuary, and channel dredging deepened the estuary. These human activities changed both the longitudinal and lateral estuarine circulations. The longitudinal circulation was observed to increase with the deepening and narrowing of the estuary. The lateral circulation experienced changes in both the magnitude and pattern. The momentum balance analysis shows that when the depth and width changed simultaneously, the longitudinal estuarine circulation was modulated by both the channel deepening and width reduction, in which the friction, pressure gradient force, and advection terms were altered. The analysis of the longitudinal vortex dynamics indicates that the changes in the vertical shear of the longitudinal flow, lateral salinity gradient, and vertical mixing were responsible for the change in the lateral circulation. The changes in water depth are the dominant factors affecting lateral circulation intensity. This study has implications for sediment transport and morphological evolution in estuaries heavily impacted by human interventions.

Sensitivity of tidal hydrodynamics to varying bathymetric configurations in a multi‐inlet rapidly eroding salt marsh system: A numerical study

AbstractWe describe the development of a high‐resolution, two‐dimensional hydrodynamic model for a multi‐inlet rapidly eroding tidal wetland on the western shore of Delaware Bay, using the finite‐volume, primitive equation community ocean model (FVCOM). Topo‐bathymetric surveys, together with water surface and current velocity measurements during calm and stormy conditions, have been conducted to support model validation. The tested model is then used to quantify the tide‐induced residual transport and asymmetry at major inlet entrances to determine the governing hydrodynamics. We chose a skewness method to calculate the tidal asymmetry and serve as a proxy for sediment transport estimates. The effects of the dredging of an artificial entrance channel and progressive channel deepening in shifting wetland hydrodynamics are shown by developing a scenario analysis. Model results show that the artificially dredged channel has altered the volume exchange at other inlet entrances and increased the net seaward export. The changes in the characteristic frequency of the frictional dissipation in the channel and the system's natural frequency are investigated using a simple ocean–inlet–bay analytical model. Subsequently, we have compared the channel friction scale to the inertia scale and observed that the new connection and gradual channel deepening reduce the overall frictional dominance. Ultimately, the study has shown how the short‐ and long‐term channel bathymetry changes, mainly the artificially dredged channel and progressive channel deepening, can affect the connected system's net circulation and trigger internal marsh erosion.

Response of Estuarine Circulation, Stratification and Sediment Transport to Channel Deepening and Narrowing

Response of Estuarine Circulation, Stratification and Sediment Transport to Channel Deepening and Narrowing

A new measuring method of dredging concentration based on hybrid ensemble deep learning technique

Aiming at the problems of safety, management, environmental protection, virtual sensor technology of dredger slurry concentration based on a hybrid ensemble deep learning (HEDL) framework is proposed. The purpose of this paper is to use the dredging construction big data, through the method of artificial intelligence, to deeply excavate the hidden relationship between the slurry concentration and the construction monitoring parameters in the construction process to generate virtual sensors, and then overcome some limitations of physical sensors. Firstly, this method removes the time lag effect of the monitoring data of physical sensors and then selects variables potentially related to the mud concentration. It makes full use of the advantages of each model to build a HEDL dredger slurry concentration prediction and measurement model embedded with multiple intelligent algorithms. The base learner of the model includes Deep Belief Network (DBN), Muti-Layer Perception (MLP), Convolutional Neural Networks (CNN), Gated Recurrent Neural Networks (GRU), Long Short-Term Memory (LSTM), Support Vector Regression (SVR). Finally, taking the Tianjin Port Channel Deepening Project as an applied research case, the accuracy and applicability of slurry concentration virtual sensors are verified.