Coastal Transport Research Articles

Coastal dynamics on equatorial beaches of amazonian coast during extreme tide events

This paper describes the influence of tidal currents on sediment transport on Amazonian equatorial beaches during extreme events. The study area (Salinópolis city) was divided into two sectors: western (Sampaio tidal channel) and eastern (Atalaia Island). Field surveys were conducted in 2013 during two periods of highest tides: April (the rainy season) and October (the less rainy season and Spring Equinox). The optical backscatter sensors (tide, turbidity, and wave data) and current meter sensors (velocity field data) were programmed to collect data every 0.1 and 60 seconds, respectively. They operated together for 24/12 hours on the upper shoreface (surf zone). Wave heights were higher in the Atalaia Island (up to 1 meter during the less rainy season). The currents were stronger, reaching 1.2 m.s-1, during ebb tide in the rainy season (Sampaio tidal channel). Higher turbidity values (maximum 1,200 FTU) occurred at the Atalaia Island during the less rainy season. The coastal dynamics in the area derives mostly from the Amazonian continental shelf, where intense tidal currents interact with a high volume of particulate debris, especially fine sand in Salinópolis. Nevertheless, estuaries and tidal channels are also largely responsible for sediment supply and play a key role in shoreline stability and coastal transport, especially during extreme tide events.

Predicting larval alewife transport in Lake Michigan using hydrodynamic and Lagrangian particle dispersion models

AbstractSeveral species of fish in large lakes and marine environments have a pelagic larval stage, and are subject to variable transport that can ultimately regulate survival and recruitment success. Alewife, Alosa pseudoharengus, are subject to transport by complex coastal currents during their pelagic larval stage (~ 30 d). We assessed backward‐trajectory simulations, consisting of a Lagrangian particle dispersion model linked to the Finite Volume Community Ocean Model, to estimate likely hatch locations of aged larval alewife collected from locations on both the eastern and western sides of Lake Michigan during July 2015. We used four deployments of three satellite‐tracked drifter buoys in coastal waters to assess model skill in estimating the origin of a drifter from its final location. We found that the trajectories of drifters varied greatly, depending on wind events and associated coastal transport processes, including upwelling/downwelling and coastal jet currents. In 2 of 12 cases, the backward trajectory simulations failed to predict the drifter origin, associated with transport of 170 km in a narrow coastal jet current. In the remaining 10 cases, the known drifter origin was within 3.5 km of the spatial patch of predicted possible origins for a scenario of horizontal diffusivity (188 m2 s−1) consistent with the offshore model grid resolution. Modeled backward trajectories estimated that alewife originated from the same side of the lake where they were collected, within ~ 100 km of the collection site. Our paper demonstrates the utility of hydrodynamic models to estimate a region of origin for aged larval fish.

Longshore sediment transport rate from the field measured wave and sediment characteristics along the coast of Karaikal, India

ABSTRACT The change in the shoreline greatly influences the coastal developments such as maritime trade, fishing activities, coastal transport, and tourism. Due to the requirements of vast developments along the coast near major habitat zones, such as the Karaikal coast along the east coast of India, it is essential to understand the longshore sediment transport (LST) movement to plan for any coastal systems to protrude. A detailed LST estimate has been made with the predicted wave climate using the wind-wave model, WAM. The wave characteristics are compared with the field measurements off the coast considered herein. The LST rates computed using five different sediment transport formulae and the method of integrating the distribution of sediment transport rates within the surf zone have been computed to understand the variations of the estimate in each method. Although the predominant direction of sediment movement is towards the north, there is a seasonal variability of LST based on the prevailing monsoon wind direction. Monitoring and analysis of the LST are important as it is required in designing coastal structures.

Investigation of Barrier Island Highway and Marsh Vulnerability to Bay-Side Flooding and Erosion

Coastal highways along narrow barrier islands are vulnerable to flooding due to ocean and bay-side events, which create hazardous travel conditions and may restrict access to surrounding communities. This study investigates the vulnerability of a segment of highway passing through the Pea Island National Wildlife Refuge in the Outer Banks, North Carolina, USA. Publicly available data, computational modeling, and field observations of shoreline change are synthesized to develop fragility models for roadway flooding and marsh conditions. At 99% significance, peak daily water levels and significant wave heights at nearby monitoring stations are determined as significant predictors of roadway closure due to flooding. Computational investigations of bay-side storms identify peak water levels and the buffer distance between the estuarine shoreline and the roadway as significant predictors of roadway transect flooding. To assess the vulnerability of the marsh in the buffer area, a classification scheme is proposed and used to evaluate marsh conditions due to long-term and episodic (storm) stressors. Marsh vulnerability is found to be predicted by the long-term erosion rate and distance from the shoreline to the 5 m depth contour of the nearby flood tidal channel. The results indicate the importance of erosion mitigation and marsh conservation to enhance the resilience of coastal transportation infrastructure.

Wind Fetch and Direction Effects on Langmuir Turbulence in a Coastal Ocean

AbstractMixing processes in the upper ocean play a key role in transferring heat, momentum, and matter in the ocean. These mixing processes are significantly enhanced by wave‐driven Langmuir turbulence (LT). Based on a paired analysis of observations and simulations, this study investigates wind fetch and direction effects on LT at a coastal site south of the island Martha’s Vineyard (MA, USA). Our results demonstrate that LT is strongly influenced by wind fetch and direction in coastal oceans, both of which contribute to controlling turbulent coastal transport processes. For northerly offshore winds, land limits the wind fetch and wave development, whereas southerly winds are associated with practically infinite fetch. Observed and simulated two‐dimensional wave height spectra reveal persistent southerly swell and substantially more developed wind‐driven waves from the south. For oblique offshore winds, waves develop more strongly in the alongshore direction with less limited fetch, resulting in significant wind and wave misalignments. Observations of coherent near‐surface crosswind velocities indicate that LT is only present for sufficiently developed waves. The fetch‐limited northerly winds inhibit wave developments and the formation of LT. In addition to limited fetch, strong wind–wave misalignments prevent LT development. Although energetic and persistent, swell waves do not substantially influence LT activity during the observation period because these relatively long swell waves are associated with small Stokes drift shear. These observational results agree well with turbulence‐resolving large eddy simulations (LESs) based on the wave‐averaged Navier–Stokes equation, validating the LES approach to coastal LT in the complex wind and wave conditions.

Invasive Dreissena Mussel Coastal Transport From an Already Invaded Estuary to a Nearby Archipelago Detected in DNA and Zooplankton Surveys.

Coastal waters of Lake Superior are generally inhospitable to the establishment of invasive Dreissena spp. mussels (both Dreissena polymorpha and Dreissena bugensis). Dreissena have inhabited the Saint Louis River estuary (SLRE; largest commercial port in the Laurentian Great Lakes) for over three decades, but only in the last few years have small colonies been found in the Apostle Islands National Lakeshore (APIS, an archipelago situated 85 km to the east of SLRE) A 2017 survey determined a low abundance Dreissena spatial distribution in APIS, with the largest colonies on the north and west islands which suggested potential veliger transport from the SLRE via longshore currents. Our objective in this study was to determine if Dreissena veligers are transported by currents at low densities along the south shore of Lake Superior from the SLRE to APIS. To do so, we used both eDNA (water and passive substrate samples) and zooplankton collection methods at eight sites evenly spaced between the SLRE and APIS with three sampling times over five weeks. Dreissena veligers were consistently detected along the south shore, although at low abundances (veligers per m3 range = 0-690, median = 8), and for every 1 km increase in distance from the SLRE, both veliger counts and water eDNA copy numbers decreased on average by 5 and 7%, respectively. D. polymorpha (suited to estuary habitats) was detected two times more than D. bugensis (better suited to deep-lake habitats). There was not a trend in the veliger size distribution along the south shore, and temperature and calcium concentrations fluctuated around the threshold for Dreissena veliger and adult development, averaging 11.0°C and 14.8 ppm, respectively. Three zooplankton taxa representative of the estuary community-Daphnia retrocurva, Diaphanosoma birgei, and Mesocyclops copepodites-decreased as the distance from the SLRE increased mirroring Dreissena veliger abundance patterns. Findings represent multiple sources of evidence of a propagule "conveyor belt" for Dreissena along the south shore of Lake Superior. We conclude that veligers are functioning as a propagule, using coastal currents to spread from the point of invasion, thereby traversing coastal habitat previously reported as inhospitable to distant habitats suitable for colonization.

Structural Analysis of Hybrid Ro-Pax Ferry

With the aim of improving the environmental sustainability in the field of maritime transport and with special reference to multimodality and 'green' solutions for coastal transport, within the METRO project (Maritime Environment-friendly TRanspOrt systems), funded under the Interreg VA CBC Programme Italy-Croatia, a project of a hybrid Ro-Pax medium range ferry for coastal navigation in the Adriatic area is developed. The paper presents a part of the conceptual design for the assessment of the global hull structure strength, which is not common for this phase of the project, and that is the structural analysis of the complete ship. For this purpose, a detailed computer model of the geometry of the whole ship was made, which includes all primary and basic secondary structural elements, with the aim that such a model can serve later as a good basis for classification and workshop documentation production during contract phase. Additionally, a preliminary calculation of the scantlings of the complete ship was performed according to BV rules and regulations using the MARS2000 software package, with regard to bending and buckling. Loads were modeled according to real conditions for two unfavorable loading conditions, and static linear analysis was performed using the LS-DYNA software package. The global analysis of bending strength in still water could reveal problematic areas in the structure.

Research into changes in ship resistance in the shallow water by numerical method

Vietnam has a long coastline and dense network of rivers and canal systems with various and complicated water depths of a waterway. According to data from the Department of Inland Waterways in 2019, Vietnam's waterways transport industry reached 250 million tons/year. In which coastal transport accounted for over 60 million tons/year, promoting the shipping industry and economic integration between regions, making the most of Vietnam's natural coastal conditions. In most general cases, the vessels working in the different water depths of the operational area will significantly affect the ship and wave field resistance. For the transport vessels with low speed, the research of the effect of resistance and wave field has an essential role in ensuring the primary maritime aim of energy saving and energy efficiency. Nowadays, computation fluid dynamics is a practical approach for predicting the ship's hydrodynamic features. However, many computation fluid dynamics types of research have investigated the ship resistance in deep water, which can not consider the effect of changing ship resistance with different water depths. In shallow water, the increasing pressure gradient field leads to an increase in the overall resistance. Therefore, in this study, the volume of fluid (VOF) multiphase model can show the free surface effect and wave elevation in shallow waters. The results clearly showed the success of the computational modeling of multiphase flows around the vessel (air and water). The wavefield in the computation fluid dynamics results is also suitable for related published research experiments. Besides, the resistance and wave elevation around the hull is significantly changing at different depths. In the preliminary design stage, it can apply this work to propose a suitable hull form of transport vessels for Vietnam's waterways.

Fragility Analysis of Coastal Roadways and Performance Assessment of Coastal Transportation Systems Subjected to Storm Hazards

Coastal transportation systems are extremely vulnerable due to the coupled impacts of storm surge, waves, and inundation. Existing literature has developed coastal fragility models for bridges. However, to date, flood fragility models for coastal roadways are lacking. For this purpose, the current study proposes a data-driven fragility model based on logistic regression for coastal roadways, with failure probability conditioned on distance to shoreline and inundation duration, using hindcast data for Hurricane Ike. In addition, the effect of bridge and roadway damage on transportation network performance is investigated through a case study on Galveston Island, Texas. The results indicate the spatial distribution of storm impacts on the transportation network, with select roads highly vulnerable if they are located within a couple of hundred meters of the shoreline. In addition, considering roadway damage in addition to bridge damage alone, which is the current state of the art, can have a significant impact on decreasing the performance of the transportation network. Such analyses shed light on potential policy or risk mitigation practices that are expected to be increasingly important in the future as sea level rise further reduces roadway distance to the shoreline or as storm intensity and frequency changes.

The Use of Geoinformatics in Coastal Atmospheric Transport Phenomena: The Athens Experiment

Coastal environment, an area where abrupt changes occur between land and sea, significantly affects the quality of life of a high portion of the Earth’s population. Therefore, the wide range of phenomena observed in coastal areas need to be assessed reliably regarding both data sets and methods applied. In particular, the study of coastal atmospheric transport phenomena which affect a variety of activities in coastal areas, using modeling techniques, demand accurate estimations of a range of meteorological and climatological variables related to the planetary boundary layer. However, the accuracy of such estimations is not obvious. Geoinformatics is able to fill this gap and provide the framework for the design, processing and implementation of accurate geo-databases. This paper aims to highlight the role of geoinformatics in the context of coastal meteorology and climatology. More precisely, it aims to reveal the effect on the performance of a Mesoscale Meteorological Model when a new scheme regarding the input surface parameters is developed using satellite data and application of Geographical Information Systems. The development of the proposed scheme is described and evaluated using the coastal Metropolitan Area of Athens, Greece as a case study. The results indicate a general improvement in the model performance based on the statistical evaluations of three meteorological parameters (temperature, wind speed and wind direction) using four appropriate indicators. The best performance was observed for temperature, then for wind direction and finally for wind speed. The necessity of the proposed new scheme is further discussed.

The Probability Density Estimation of Wave Direction Data in Korea

Lee, G.S.; Lee, U.J., and Cho, H.Y., 2021. The probability density estimation of wave direction data in Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 21–25. Coconut Creek (Florida), ISSN 0749-0208. Although wave direction is important information along with wave height and period, distribution estimation studies have been limited to traditional schematic analysis, including rose diagrams. In addition, studies on the estimation of the distribution function of wave direction are relatively insufficient compared to wave height and period distribution. In this study, estimations of basic statistical information and the distribution function were performed using hourly wave direction data at 16 points in the last 4 years (2016-2019) measured by the KMA (Korea Meteorological Administration) buoy. The von Mises Mixture (VMM) distribution function was used to estimate the directional data distribution, and the optimal parameters for each order were estimated using the EM algorithm. The optimal order was selected based on Bayesian Information Criterion (BIC), and generally, 4-5 VMM distribution functions were identified as the optimal distribution functions (70%). The optimal VMM distribution function was compared with the histogram and the non-parametric method for Kernel Density estimation. In addition, quantitative analysis was performed on the temporal change pattern of the mean and standard deviation of the direction data corresponding to a representative statistical measure. As a result of the analysis, it was found that a multimodal distribution was appropriate for estimating wave direction according to the overall stations and times. Therefore, one representative wave direction and standard deviation information was found to be insufficient for estimating the distribution type, and the parameters (weighting coefficient, mean, and variance) of the VMM model were found to be more effective for estimating the distribution type. The results of this study can be used in various fields of coastal engineering that require the input of wave information (coastal transport and predominance of design waves).

The Skuldelev 3 reconstruction, Roar Ege: from reconstruction to retirement

In 1982, the Viking Ship Museum embarked upon its first full-scale reconstruction of a Viking ship. The vessel in question was based on the remains of Skuldelev 3, an 11th-century coastal transport and trading vessel, which had been excavated 20 years previously. The reconstruction, Roar Ege, was launched in 1984 and retired from service in 2016, providing a complete data set over the lifespan of a reconstructed Viking ship. This article will present an object biography of Roar Ege, from the perspective of both the boatbuilder and archaeologist, detailing the manner in which the hull has deteriorated, and the components involved in its decline.

The impact of economic policy on shipper businesses in coastal line maritime passenger transport in Croatia

Coastal line maritime passenger transport in the Republic of Croatia, as well as in other EU member states, is regulated through various regulations and legislation, which in turn result in numerous national laws and regulations that affect its development, all of which is legally binding for shippers. Scheduled maritime passenger transport is an extremely important form of transport for the Republic of Croatia since it is the only form of connection with the mainland for many islands. This paper analyses economic policy measures that affect the organization and implementation of coastal line maritime passenger transport. The paper also investigates the demand fluctuation for maritime passenger transport services. The aid measures provided by the state to individual sectors is also analysed, as well as aid for the provision of services of general economic interest. The aim of this paper is to assess the amount of aid granted to maritime transport and its importance, especially in coastal line maritime passenger transport. The paper also explains the importance of establishing the Coastal Liner Services Agency as a regulatory body of the Republic of Croatia, and it further analyses the subsidy amounts granted to shippers in the period from 2014 to 2020.

Coastal transportation system green policy design model based on shipping network design

ABSTRACT As governments of various countries attach importance to green transportation, governments have focused their attention to understanding how they can shift the cargo shipping in coastal areas from land to water. Motivated by this, this paper establishes a green policy design model for coastal transportation systems. The model aims to minimise the comprehensive cost (i.e. the sum of the transportation cost and carbon emission tax) in the research area and optimise the government's shipping network design scheme and waterway freight rate control scheme under the established subsidy level. An active set algorithm is designed that can explore the local optimal solution of the model. Taking the Bohai Rim region of China as the research area, sensitivity analyses of different subsidy scales and origin-destination demand scales are carried out. The results show that the government's policy schemes will lead to a significant shift in the mode of transportation used for cargo.

Evaluation of the Efficiency of Maritime Transport Using a Network Slacks-Based Measure (SBM) Approach: A Case Study on the Korean Coastal Ferry Market

Safety is a key performance indicator for the sustainable management of a coastal ferry service business. An efficiency strategy that balances safety and transport performance should be considered. The purpose of this study is to evaluate the relative transport efficiency of coastal ferry operators through undesirable safety-related output. Coastal ferry operators create added value through logistics activities such as cargo and passenger transport. Accordingly, this study designed a three-stage network-slacks-based measure (SBM) model that delineated production through ferry transport services such as service generation, service execution, and transport value creation. Detention records and marine accidents caused by human errors or technical faults were considered undesirable safety-related outputs. Moreover, the relative transport efficiency of 23 Korean firms that have continuously managed a coastal ferry transport business from 2015 to 2018 was analyzed. The results showed that the differentiation of transport efficiency of firms improved when applying the three-stage network SBM model compared to applying the SBM model that did not consider the internal production stage. This fact suggests that it is more desirable to apply the three-stage network SBM model proposed in this study when a more stringent comparison of transport performance is needed in terms of service quality.

Seasonal to decadal scale shoreline changes along the Cameroonian coastline, Bay of Bonny (1986 to 2020)

The Bay of Bonny, located along the Cameroon coastline, is home to diverse ecosystems. It is under significant pressure from large human activity, but remains very little studied, like much of the Gulf of Guinea. In order to understand its long-term shoreline variations and the role the wave regime plays in the evolution of the coastline, a study was conducted on the basis of optical image archives from Landsat 5∕7∕8 and Sentinel-2A/2B satellite missions acquired between October 1986 and May 2020, coupled with daily ERA-Interim wave re-analysis data covering the period from January 1986 to August 2019. Overall, the results show that the evolution of the coast is highly variable in space and time, as indicated by different levels of erosion (30.55 %), and accretion (27.7 %) on the decadal-scale, with the most significant variations occurring in estuarine areas. Nevertheless, 41.75% of the Cameroon shoreline remains stable during the study period. Three main periods (1986–1994; 1995–2005; 2006–2020) during which the coast underwent significant changes a different location were identified, reaching a retreat rate of up to −10 m/year in the northern section during the first period 1986–1994. The annual trend of significant wave heights anomaly along the coast (−5.6 to −4.1 mm/year) with wave height maxima estimated at 1.46 ± 0.65 m, where observed during the summer months (July–August). Monthly shoreline changes are inversely correlated with wave climate in some segments. Eigenvalue orthogonal decomposition analyses (Mode 1, Empirical Orthogonal Function) show that 76.3% of the observed variability would be due to the relatively strong local influence of erosion and accretion. This local influence can be related to wave regime at shorter timescale (monthly to seasonal) and the sediment variability from the source inland to the coast at longer timescale (seasonal to decadal). These observations explain a complex pattern of shoreline changes with an almost continuous retreat shoreline during the period 1986–2013 and a reversal in trend towards accretion during the period 2013–2020. EOF mode 2 explains 23.7% of variability, which can be potentially associated with the synergetic relationship between tidal currents and wave-induced longshore current, tidal currents and possibly pockets of human activity. This is attributed to an overall decrease in the supply of sediment via the coastal transport system that prevails in the Gulf of Guinea.

Probabilistic Risk Assessment of Coupled Natural-Physical-Social Systems: Cascading Impact of Hurricane-Induced Damages to Civil Infrastructure in Galveston, Texas

The combined effect of storm surge and wave action during severe storms in coastal regions can cause significant damage to civil infrastructures with cascading consequences to coastal communities and their residents with respect to emergency response, repair, and recovery. This coupling of natural, physical, and social systems presents an important yet relatively underexplored problem in the probabilistic risk assessment of coastal systems. Not only does coupling exist among the built and social systems triggered by natural hazard events, but a wealth of sources of uncertainties inherent in modeling these systems also renders the problem more complex. This paper presents a framework for the probabilistic risk assessment of coupled natural-physical-social systems exposed to coastal storms. It departs from traditional literature in this area by considering interconnected coastal transportation and residential building infrastructure coupled with social systems—households in this case—focusing on households failing to respond to official calls to evacuate. A holistic multihazard risk assessment framework is posed for probing these coupled systems in the face of uncertainty. New hybrid risk metrics across built and social systems are proposed, including the probability of nonconnectivity to emergency services, time loss to access emergency services, and the number of nonevacuees at risk. The concept of a hot household is developed, at which a building with nonevacuees inside experiences collapse-limit failure and is disconnected from emergency services during a storm event. The proposed framework is applied to a case study on Galveston Island, Texas, considering uncertainties in storm frequency and intensity, damage to physical infrastructure (buildings, roadways, and bridges), and evacuation decisions of the population. The resulting models offer a foundation for risk-informed decision-making to enhance the resilience of coastal communities and provide new insight into the coupled performance of natural-physical-social systems in the face of coastal storms.

On the Performance of High Frequency Radar in the Western Mediterranean During the Record-Breaking Storm Gloria

Storm Gloria (January 19–24, 2020) hit the NW Mediterranean Sea with heavy rainfall, strong easterly winds, and very high waves, causing structural damages and 13 fatalities. The low-lying Ebro Delta (ED) region was severely inundated, ruining rice fields and seaside promenades. A variety of Copernicus Marine Environment Monitoring Service (CMEMS) modeling and observational products were jointly used to examine the fingerprint of Gloria and the response of the upper oceanic layer. According to the results, Gloria can be interpreted as a high-impact once-in-a-decade metocean event where various historical records were beaten. The 99th percentile of several parameters (wind speed, significant wave height, wave period, and surface current velocity), derived from long-term observational time series, was persistently exceeded. The atmospheric surge, albeit not negligible, exerted a secondary role in ED. The ability of a high-frequency radar deployed in this region (HFR-ED) to characterize the striking features of the storm was quantified from both waves and circulation aspects. Consistent radar current observations were subsequently compared against the 5-day-ahead forecast of CMEMS Iberia-Biscay-Ireland (IBI) regional ocean model to determine, from an Eulerian perspective, the strengths and shortcomings in its predictive capabilities. Time-averaged maps of surface circulation, superimposed with fields of Instantaneous Rate of Separation (IROS), were derived to resolve flow features and identify areas of elevated particles dispersion, respectively. The mean and P99 values of IROS almost doubled the historical statistics in the vicinity of the northern Ebro hemidelta. Although IBI predicted moderately well basic features of the storm-induced circulation, results suggests that coastal transport processes, likely modulated by wave-current interactions, were not fully captured. Furthermore, current estimations from other two radar systems, overlooking immediate choke points like the Ibiza Channel and the Strait of Gibraltar, evidenced Gloria’s remote-effect in the anomalous circulation patterns observed, that altered the usual water exchanges between adjacent sub-basins. Finally, three-dimensional outcomes from IBI were used to elucidate the impact of this moving storm at different depth levels. Data analyses illustrated that Gloria caused a large increase in kinetic energy and a significant deepening of the mixed layer depth.

Seasonal variations in the water residence time in the Bohai Sea using 3D hydrodynamic model study and the adjoint method

The Bohai Sea is a large, semi-enclosed bay of China with a transport timescale of more than 1 year. Residence time (RT) is an important indicator used to determine the water exchange rate of coastal oceans, and it has a significant influence on coastal ecosystems and the environment. In this study, the RT and its seasonal variability within the Bohai Sea were investigated using a 3-D hydrodynamic model and the adjoint method of the RT. The model results show that the annual mean RT in the Bohai Sea is 3.43 years, and the RT increases from the Bohai Strait to the northwestern coast. The seasonal variability of the RT averaged over the entire Bohai Sea is not obvious; however, the regional RT has a significant seasonal variation, which could be more than 290% on average. When the monsoon winds were removed from the model, the sensitivity experiment showed an annual mean RT increase of ~ 90% with negligible seasonal variations in most areas of the Bohai Sea. The wind-induced residual current controls the seasonal variation in ocean circulation and induces the seasonal variability in RT; thus, monsoon winds play a dominant role in the seasonal variations of the water exchange rate in the Bohai Sea. Sensitivity experiments also suggest that tides can slow the water exchange rate, whereas the baroclinic processes and river runoff can accelerate the water exchange rate in the region near the Yellow River estuary. This study highlights the critical role of monsoon winds in affecting seasonal variabilities in the coastal transport timescale and exchange rate.

MODELLING TRANSPORT AND FATE OF WOODY DEBRIS IN COASTAL WATERS

Woody debris is ubiquitous in coastal waters, and on shorelines proximate to forested regions. Logs and driftwood play a vital role in coastal and global ecosystems, and can provide valuable data to support studies of oceanography, geomorphology, ecology, history and archaeology. There is growing interest in the role that woody debris can play in nature-based coastal engineering solutions. However, large quantities of woody debris in coastal waters can pose significant hazards to communities, infrastructure, navigation and ecosystems. Thus, the changing abundance and distribution of coastal driftwood, driven by factors including human activities and climate change, has potential for both positive and negative consequences. A better understanding of coastal driftwood fate and transport processes is needed to inform management practices, uses, and sustainable ecosystem management. To date, research on physical transport of woody debris, has been concentrated on tsunami and inland (riverine) environments, where spatiotemporal scales and driving processes are significantly different from typical climatic or even extreme (storm) conditions in coastal waters. In this paper, we describe a series of scale physical model experiments, conducted to provide insight to debris transport processes in coastal waters under a range of controlled wave and water level conditions. The experiments were conducted in a 50.4-metre by 29.4-metre wave basin, in which a 1/30 scale model of a natural shoreline comprised of a shallow fringing reef, a sandy shoreline, and several small coastal structures (groynes and breakwaters) was constructed. Wooden dowels and tree branches, scaled to replicate the size distribution of woody debris observed on Pacific Northwest shorelines, were released in the model. Despite some limitations (e.g., model scale effects), the experimental test results provided several valuable insights to factors affecting debris mobility in coastal areas. The results will inform the parameterization of important physical processes in a numerical model being developed to predict the fate and transport of woody debris in coastal waters.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/hvBHZVObDhY