Macrotidal Area Research Articles

Optimization of Influencing Factors in Tidal Current Data Assimilation Modeling in Macro Tidal Estuary, Gyeonggi Bay, South Korea

Gu, B.-H.; Woo, S.-B., and Kim, S., 2021. Optimization of influencing factors in tidal current data assimilation modeling in macro tidal estuary, Gyeonggi Bay, South 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. 66–70. Coconut Creek (Florida), ISSN 0749-0208. The study investigates the effect of the model prediction accuracy improvement using data assimilation technique in macro-tidal estuary, such as the Gyeonggi Bay (GGB), South Korea. The observation data used in this study is a tidal current measurement from Acoustic Doppler Current Profiler (ADCP) mooring device. GGB is located at the middle west coast of South Korea, and it is semi-closed estuary that has a tidal range over 6.8 m. To take the irregularity of coastline into account, this study utilized the Finite Volume Coastal Ocean Model (FVCOM), which has the flexible advantage of grid resolution by using unstructured triangular grid system. When applying data assimilation into the coastal model, various parameters, such as scaling factors and correlation lengths are needed to be adjusted to find out the best performance. Total 25 cases used in Taylor diagram showed that different influencing factors are required to be optimized at each observation location. It means that parameters in data assimilation depend on the physical dynamic system via complicated geometry. The optimized parameters not only increase by the tidal range but also it is offset by the effect of river discharge. The horizontal influence range of data assimilation with all observed locations becomes even less than the result applying only one location. It is estimated that the phenomena occurred due to strong tidal currents and interference between the range of influence. The sensitivity of data assimilation parameters in tidally dominated coastal area indicates that a systematic way of choosing the most optimized site-specific parameters are required in macro tidal area.

Intelligent Buoy System (INBUS): Automatic Lifting Observation System for Macrotidal Coastal Waters

The west coast of South Korea is characterized by a wide macrotidal area with a maximum tidal range of ∼10 m. The sea surface elevation varies with the tidal phase, which leads to significant changes in the vertical structure of the physical, chemical, and biological properties of the water column, especially when the interaction by waves and/or the freshwater and sediment input from the river increases. Under such conditions, it is difficult to carry out continuous and consistent measurements of the vertical structures of the water qualities using a conventional observation system that is fixed to the seabed or sea surface because the thickness of the water column constantly changes. Based on the demand for long-term observations of the vertical structures of the water properties in macrotidal environments, the Intelligent Buoy System (INBUS) was developed by the Korea Institute of Ocean Science and Technology (KIOST). INBUS is a buoy equipped with an instrument frame, which is similar to other buoys that are fixed to the sea surface. During every measurement, INBUS detects the water depth and sends the frame down to the seabed to measure the water quality at every vertical level set up in the system. For example, if N levels are set in INBUS, the water depth of each measurement is divided by N layers and the instruments in the lifting frame measure the water properties of each of the N layers while they are descending to the bottom. Based on this procedure, the vertical structure of the water column is consistently measured in N layers regardless of changes of the water depth due to tides and waves. The lifting and measuring process is automatically controlled by INBUS once it is set up in the system. In addition, because INBUS allows bidirectional communication through code division multiple access (CDMA), the system can be controlled by stations on land. If the CDMA communication becomes inoperable owing to extreme wave conditions or the buoy is lost because of incidents such as a collision with a ship, the location of INBUS can be tracked by low-earth-orbit satellites.

Morphological Characteristics of Low-angle Dunes on a Tidal Ridge, the Jiangsu Macrotidal Coast, China

Wang, L.; Yu, Q.; Zhang, Y., and Gao, S., 2020. Morphological characteristics of low-angle dunes on a tidal ridge, the Jiangsu macrotidal coast, China. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 717-721. Coconut Creek (Florida), ISSN 0749-0208.Subaqueous dunes are typical flow-transverse rhythmic bedforms in fluvial, intertidal and marine environments. The low-angle dunes (LADs), commonly associated with a leeside angle of less than 15°, differ in terms of the formation mechanism from the high-angle dunes (HADs). Here, multibeam echosounder exploration and seafloor surficial sediment sampling were carried out on a tidal sand ridge off the Jiangsu coast, China, a macrotidal area with the spring tidal range exceeding 6 m. The spatial distribution of the dune morphological parameters, including wave height, wavelength, asymmetry, and lee-side angle, are analyzed in association with the water depth and seafloor sediment. The following results are obtained. (1) Two-dimensional linear dunes are superimposed on the tidal ridge, and a total of 3599 dunes detected are all LADs with an average maximum leeside angle of 5.46°. (2) The spatial distribution of the dune parameters is closely related to the topography of the ridge-swath system. The asymmetries and migration directions of the dunes on the northern and southern slopes of the tidal ridge are opposite, indicating a clockwise residual sand circulation, while the ridge represents the transition zone with relatively symmetrical dunes. (3) Water depth is the controlling factor for the dune geometry in shallow water places. In areas where water depth is below 7.5 m and the seafloor sediments are composed of pure sand, the scales of LADs are proportional to the water depth. (4) Bed sediment composition becomes important for the deeper water areas. For water depth more than 7.5 m, the ratio of cohesive particles (< 8 µm) of bed sediment, which increases with the water depth, inhibits the growth of the LADs. These observations reveal the behavior of LADs in association with sediment particle size and water depth.

What species make up the Nike fish assemblages at the macrotidal estuary in Gorontalo Bay, Indonesia?

Background:No study has documented the species composition of Nike fish (fam: Gobiidae) schools. The aim of this study is to document the species composition of the Nike-fish schooling.Methods:All samples were collected randomly from fisher’s catch during the fishing season on 5th–11th October 2018 at macrotidal area in Leato. Then, all specimens were identified morphologically by melanophore pattern differences. Subsequently, all identified-samples by melanophores pattern differences were sent to the genetic laboratory for identification.Results:The morphological results show there are five individuals with a different melanophores pattern. On the contrary, the genetic results only show four species from those five individuals. They areSicyopterus pugnans, S. cynocephalus, Belobranchus segura,andBunaka gyrinoides.Conclusions:Our findings show that there are only four species that compose the Nike fish schooling in Gorontao Bay. They areSicyopterus pugnans, Sicyopterus cynocephalus, Belobranchus segura,andBunaka gyrinoides.

SENSITIVITY OF OCCURRENCE FREQUENCY OF STORM TIDE ELEVATION TO RANDOM TIDAL PHASES IN MACRO-TIDAL AREA

Storm tides result from meteorological forces (storm) acting over tidal waters. To derive the reoccurrence frequency of storm tide elevation (STE), of particular interest is to reduce the bias due to random tide selection, since the storm occurrence is independent of tidal phase. This aleatory bias can be reduced by modelling each storm at increasing number of random tides, which, however, adds to the computational cost. Therefore, it is useful to investigate the number of random tides required for each storm to reduce the concerns of aleatory bias. This study firstly explored the nonlinear interaction between tide and surge for a single extratropical (ET) storm in a macrotidal study area. In general, the non-linearity is 90 degrees out of phase with tide. Although the nonlinearity is important, especially over tidal flats, it is a second order term to the linear combination of tide and surge. This enables the possibility to evaluate the sensitivity of occurrence frequency of storm tides to the number of random tidal phases through a Monte-Carlo Simulation (MCS), where storm tides with surge occurring at random tidal phases can be derived by linear super-position. It was determined that the variance of 100-year STE can be significantly reduced if 10 or more random tides for each storm are considered. It is also possible to eliminate the bias using the MCS with the nonlinearity accounted for by linear regression relating modeled STEs and that derived from linear superposition. The accuracy of the approach can be estimated by introducing the regression error randomly to the STEs obtained from linear regression during the analysis.

MARINE MODELLING IN SUPPORT OF KOOLAN ISLAND MINE RECOMMENCEMENT AND EVENTUAL DECOMMISSIONING

Koolan Island is located in a remote macrotidal (9m mean spring range) area of the Buccaneer Archipelago of NW Australia. High-quality hematite has been mined from the island since the 1940s, with direct export by ore carriers from a dedicated marine terminal. Mining in recent decades has focused on an open pit immediately adjacent to the ocean. The initial operator decommissioned the site in 1993, at which time a channel connecting the pit to the sea was excavated, the pit was flooded and a productive marine ecosystem developed within the photic zone of the former mine. The site was subsequently acquired by Mt. Gibson Iron, which drained the pit in 2007 and constructed a protective seawall to facilitate additional ore extraction through the extension of the pit both in depth as well as closer to the historical shoreline. A catastrophic failure of a section of the seawall in 2014 re-flooded the pit, which resulted in no injuries as the site was successfully evacuated in response to instrumented movements in the seawall structure. Construction of a strengthened seawall has recently been completed, and pit dewatering activities will be initiated during the week of the ICCE conference to enable in-Pit mining activities to recommence by the end of 2018. The presentation will present a summary of the unique history of the site, as well as supporting numerical modelling performed to describe a) the complex regional and local macrotidal dynamics, b) sediment spillage in connection with the reconstruction of the seawall following the 2014 failure, and c) coupled 2D/1D model calculations optimizing channel geometry to ensure adequate flushing of the pit following its eventual re-flooding in connection with final decommissioning.

Estimation of Probable Maximum Sea Level at Macro-tidal Area

The concept of probable maximum sea level was applied to estimate design tide level of which could be applied to a very restricted design requirement such as a nuclear power plant. Furthermore, regarding macro-tidal area such as West Coast, empirical simulation technique was applied as sea level needs to be estimated with considering both tide and typhoon surge. The return period has been set up for 10,000 years, and the sea level was simulated by generating hypothetical typhoon in order to typhoon-surge event which is included in training set. If one year among advanced generation of high tide data for 20 years, is selected, maximum sea level would be set by combination of single typhoon-surge event of the training set in certain time frame. Sea level of 10,000 year return period and others would be estimated by this hypothetical generation. In addition, in order to reflect future climate change, enlargement in storm intensity which could be led more than 20% stronger and increase in sea level regarding RCP 8.5 scenario on the basis of 2100. The probable maximum sea level was ultimately estimated by calculating the maximum extent of confidence intervals in order to maximize the sea level.

Wave–tide interactions during a strong storm event in Kyunggi Bay, Korea

Wave propagation conditions and wave–tide interactions are studied in a tide-dominant bay area during a strong storm event with a speed of 15–20ms−1 during the study period of March 3–8, 2007. The study area is Kyunggi Bay, which is a large estuarine system in the west coast of Korea, a well-known macrotidal area. To investigate wave–tide interactions, a series of numerical experiments were designed to determine significant factors that contribute to wave height deformation and periodic wave-height modulations during a strong passing storm. The findings suggest that the periodically occurring wave height modulations at onshore and near coastal areas are mainly caused by the water depth changes by tide, which means that more wave energy can propagate into the coastal area increasing the wave height. The wave propagation was changed by tide, and the peak wave period was increased during the flood and decreased during the ebb tide. Although the effect was relatively weak, the tidal current also contributed to the increase and decrease of wave height during the flood and the ebb. It is worth noting that the wind was not a factor of periodic wave-height modulations, but it played a role in increasing the wave height.

Feeding ecology of immature Lithodoras dorsalis (Valenciennes, 1840) (Siluriformes: Doradidae) in a tidal environment, estuary of the rio Amazonas

Studies of feeding ecology are important for the evaluation of interactive processes in fish communities. This study evaluated the feeding ecology of Lithodoras dorsalis (Doradidae) from streams within the Amazon estuary delta (Brazil), a macro-tidal area, on different pluviometric periods. A total of 371 young specimens was collected during 12 months of sampling (July 2010 to June 2011). The species diet was composed of 28 food items analyzed by Repletion Index, Alimentary Index and Niche Breadth. Young L. dorsalis was classified as herbivore with a frugivory tendency due to the high importance of fruit and seeds in its diet. Food intake varied among sampled months, with the lowest intake being recorded during the rainy-dry season transition period, and the highest at the beginning of the dry season. The importance of food items and the composition of the diet were different throughout the year, probably due to the daily tides that allow fish to access new environments and the pluviometric periods. These results provide important data on the feeding ecology of Amazonian doradids. The study also emphasized the importance of allochthonous resources, derived from the riparian forest, which reinforces the importance of this habitat for the conservation of Neotropical freshwater fishes.

In-situ database toolbox for short-term dispersion model validation in macro-tidal seas, application for 2D-model

Appropriate field data are required to check the reliability of hydrodynamic models simulating the dispersion of soluble substances in the marine environment. This study deals with the collection of physical measurements and soluble tracer data intended specifically for this kind of validation.The intensity of currents as well as the complexity of topography and tides around the Cap de La Hague in the centre of the English Channel make it one of the most difficult areas to represent in terms of hydrodynamics and dispersion. Controlled releases of tritium—in the form of HTO—are carried out in this area by the AREVA-NC plant, providing an excellent soluble tracer. A total of 14,493 measurements were acquired to track dispersion in the hours and days following a release. These data, supplementing previously gathered data and physical measurements (bathymetry, water-surface levels, Eulerian and Lagrangian current studies) allow us to test dispersion models from the hour following release to periods of several years which are not accessible with dye experiments. The dispersion characteristics are described and methods are proposed for comparing models against measurements.An application is proposed for a 2 dimensions high-resolution numerical model. It shows how an extensive dataset can be used to build, calibrate and validate several aspects of the model in a highly dynamic and macrotidal area: tidal cycle timing, tidal amplitude, fixed-point current data, hodographs.This study presents results concerning the model's ability to reproduce residual Lagrangian currents, along with a comparison between simulation and high-frequency measurements of tracer dispersion.All physical and tracer data are available at 〈http://doi.pangaea.de/10.1594/PANGAEA.762253〉. This tool for validation of models in macro-tidal seas is intended to be an open and evolving resource, which could provide a benchmark for dispersion-model validation.

Tidal influences on fish distributions on tropical eastern Pacific rocky shores (Colombia)

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 416:241-254 (2010) - DOI: https://doi.org/10.3354/meps08768 Tidal influences on fish distributions on tropical eastern Pacific rocky shores (Colombia) Gustavo Adolfo Castellanos-Galindo1,2,*, Uwe Krumme1, Trevor J. Willis3 1Leibniz Center for Tropical Marine Ecology (ZMT), Fahrenheitstr. 6, 28359 Bremen, Germany 2Grupo de Investigación en Ecología Animal, Departamento de Biología, Universidad del Valle, A.A. 25360, Cali, Colombia 3National Institute of Water and Atmospheric Research Ltd, PO Box 893, Nelson 7040, New Zealand *Email: gustavoa80@yahoo.com ABSTRACT: On coasts with high tidal ranges, fishes regularly establish linkages between subtidal and intertidal habitats via tidal movements, such that the home range incorporates habitat that is only intermittently available. To examine the responses of shallow-water reef fish assemblages to tidal water level changes in a macrotidal area of the tropical eastern Pacific, daytime underwater visual fish surveys were carried out in intertidal and subtidal zones at different tidal stages in Utría National Park, Colombia. Labridae and Pomacentridae were the most abundant families, but species within these families changed between intertidal and subtidal zones. Of 106 species, >70% used the rocky intertidal zone. Benthic opportunistic reef species comprised ca. 85% of the intertidal migrant species, whereas the remaining 15% corresponded to ubiquitous reef and pelagic species. Little variation in subtidal and intertidal fish assemblages was observed between spring and neap tides, but there were large changes detected over the tidal cycle that were attributed to species-specific use of the intertidal zone at high tide. Intertidal fish assemblages comprised a defined subset of species that differed significantly from those of subtidal areas. Rocky intertidal habitats are used only haphazardly by most reef fishes, but a few common species shifted more than 90% of their population into intertidal habitats during high tide, indicating that for those taxa, intertidal habitats provide important foraging opportunities. This may introduce a significant source of local-scale bias to density estimates of subtidal reef fishes, and reef fish monitoring programmes should specifically factor tidal state as a controlling influence in macrotidal areas. KEY WORDS: Tidal migrations · Rocky intertidal · Reef fishes · Tropical eastern Pacific · Utría Full text in pdf format PreviousNextCite this article as: Castellanos-Galindo GA, Krumme U, Willis TJ (2010) Tidal influences on fish distributions on tropical eastern Pacific rocky shores (Colombia). Mar Ecol Prog Ser 416:241-254. https://doi.org/10.3354/meps08768 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 416. Online publication date: October 14, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.

The AMANDES tidal model for the Amazon estuary and shelf

The AMANDES project aims to study transports from the Andean mountains to the Atlantic Ocean through the Amazon system. This requires realistic estuarine modelling in this area strongly forced by tides and river discharge. As none of the existing models for this region would fit the actual needs of the project, a specific new generation model has been implemented. The model is based on the hydrodynamic finite element model T-UGOm. In a first step, we limit our investigations to tidal dynamics. As the Amazon estuary is a very shallow macro-tidal area, it is necessary to improve the available bathymetries and to develop a precise bottom friction parametrisation. In this paper, we discuss the implementation of a high resolution regional model. This allows us to develop a precise and accurate tidal model: for instance, the overall root mean square error on complex differences is reduced from 54 cm in a standard model to 27 cm in our best model. Such precise and accurate tidal modelling is a prerequisite for modelling particle transport.

Mangrove Habitat Dynamics and Sea-level Change. A Scenario and GIS Mapping of the Changing Process of the Delta and Estuary Type Mangrove Habitat in Southwestern Thailand.

The team revealed the structure of habitat dynamics and evaluated the effects of the rapid sea-level rise due to greenhouse effects based on the biogeomorphological, interdisciplinary field research in Thailand and Malaysia. During the gradual sea-level rise (2,000 to 1,000 yrs.B.P.), the mangrove habitat is able to keep its vertical situation in the tidal range by accumulatien of mangrove organic materials and fluvial sediment. In the phase of stable sea-level, during the past 1,000 years, the habitat raised its vertical situation from mid to higher portion in the tidal range. The stable condition of sea-level in the past 1,000 years is very important for evaluating the survivability of the habitat by rapid sea-level rise. In the macrotidal area, such as the Andaman sea coast mangroves, the vertical situation of the habitat is located O.5 to 2 meter higher than mean sea-level because of the large sedimentation and the ]large tide amplitude. The mangrove habitat where located in the macrotidal area which has been preserved in spite of great change in the inner structure of mangrove forest by 50 cm rise of sea-level in 100 yrs. because of the higher location of the habitat and the gradual accumulation of mangrove organic materials. The influence of rapid sea-level rise is relative]y severe.in the microtidal area. The reason suggested that is the thinner tidal area of the upper portion of the micretidal range has greater effects from the rapid sea-level rise. As a result, three factors which play a great role in the estimation of habitat change are as follows: {1) the velocity of sea-level rise, (2) the tidal amplitude and (3) the rate of sedimentation. The tidal amplitude is more or less 2 m in almost at the coastal area of the world]d. In case of less than 50 cm (5 mm/yr) rise of sea-level we can think that mangrove habitat can survive in almost all the area. In such case the mangrove forest can accumulate the organic material. It means that mangrove forest has a role]c of CO2 sink and that mitigates the global warming.

Do hydrodynamic factors affect the recruitment of marine invertebrates in a macrotidal area? : The case study of Pectinaria koreni (Polychaeta) in the Bay of Seine (English Channel)

For marine benthic invertebrates exhibiting complex life cycles, changes in populations' distribution and abundance are governed by a large variety of physical, chemical and biological processes. From field observations in the Bay of Seine and laboratory experiments conducted since 1987 on the polychaete Pectinaria koreni, the present study highlights the relative importance of hydrodynamical and biological factors which affect individuals within both the planktonic and benthic phases at different scales of space and time in a macrotidal area. Pectinaria koreni is one of the main macrofaunal component of the Abra alba muddy fine sand community of the eastern Bay of Seine. Despite a highly advective and diffusive environment, a relative larval retention near adult population was reported due to some local hydrodynamics features (e.g. tidal residual circulation, Seine river plume front) and the interaction between the vertical current structure and the larval vertical migration. Although larval retention could be disrupted by wind induced currents, multiple spawning events over the reproductive period increase the likelihood that at least one larval cohort ensures a high recruitment during the life-span. Following a massive settlement whatever the sediment grain size, the newly settled larvae exhibited a high immediate decrease of their densities as a result of postlarval mortality and migration. Postlarval drifting was induced by a combination of physical factors (i.e. tidal currents and swell) and postlarval behaviour in response to sediment texture and adult/settlers interactions. According to the hydrodynamics of the bay, this process may generate a postlarval transport from offshore bottoms to coastal suitable habitats and counteract the demographic effects of larval dispersal. A conceptual model of factors governing the recruitment and population maintenance of Pectinaria koreni is proposed and discussed in comparison with results obtained on another polychaete, Owenia fusiformis, in the same area.

Patterns of Sediment Accumulation in the Tidal Marshes of Maine

One year’s measurements of surficial sedimentation rates (1986–1987) for 26 Maine marsh sites were made over marker horizons of brick dust. Observed sediment accumulation rates, from 0 to 13 mm yr−1, were compared with marsh morphology, local relative sea-level rise rate, mean tidal range, and ice rafting activity. Marshes with four different morphologies (back-barrier, fluvial, bluff-toe, and transitional) showed distinctly different sediment accumulation rates. In general, back-barrier marshes had the highest accumulation rates and blufftoe marshes had the lowest rates, with intermediate values for transitional and fluvial marshes. No causal relationship between modern marsh sediment accumulation rate and relative sea-level rise rate (from tide gauge records) was observed. Marsh accretionary balance (sediment accumulation rate minus relative sea-level rise rate) did not correlate with mean tidal range for this meso- to macro-tidal area. Estimates of ice-rafted debris on marsh sites ranged from 0% to >100% of measured surficial sedimentation rates, indicating that ice transport of sediment may make a significant contribution to surficial sedimentation on Maine salt marshes.