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Lei, J., F. Li, S. Zhang, H. Ke, Q. Zhang i W. Li. "ACCURACY ASSESSMENT OF RECENT GLOBAL OCEAN TIDE MODELS AROUND ANTARCTICA". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W7 (14.09.2017): 1521–28. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w7-1521-2017.
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Due to the coverage limitation of T/P-series altimeters, the lack of bathymetric data under large ice shelves, and the inaccurate definitions of coastlines and grounding lines, the accuracy of ocean tide models around Antarctica is poorer than those in deep oceans. Using tidal measurements from tide gauges, gravimetric data and GPS records, the accuracy of seven state-of-the-art global ocean tide models (DTU10, EOT11a, GOT4.8, FES2012, FES2014, HAMTIDE12, TPXO8) is assessed, as well as the most widely-used conventional model FES2004. Four regions (Antarctic Peninsula region, Amery ice shelf region, Filchner-Ronne ice shelf region and Ross ice shelf region) are separately reported. The standard deviations of eight main constituents between the selected models are large in polar regions, especially under the big ice shelves, suggesting that the uncertainty in these regions remain large. Comparisons with in situ tidal measurements show that the most accurate model is TPXO8, and all models show worst performance in Weddell sea and Filchner-Ronne ice shelf regions. The accuracy of tidal predictions around Antarctica is gradually improving.
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Bouchkara, M., K. El Khalidi, A. Benazzouz, N. Erraji Chahid, I. Joudar, B. Zourarah i M. Maanan. "STUDY OF MORPHODYNAMIC AND SEDIMENTOLOGICAL CHANGES IN THE OUALIDIA LAGOON (MOROCCO) USING BATHYMETRIC DATA: FIRST INVESTIGATIONS AFTER THE SEDIMENT TRAP DREDGING". International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVI-4/W3-2021 (10.01.2022): 53–63. http://dx.doi.org/10.5194/isprs-archives-xlvi-4-w3-2021-53-2022.
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Abstract. Coastal lagoons are highly dynamic and physically complicated systems. They are environmentally productive and socio-economically valuable. Contemporary global development and management pressures require a better understanding of their dynamics and sustainability. The present study focuses on the problem of water confinement in the Oualidia lagoon (Atlantic coast of Morocco). This lagoon is characterized by an asymmetric tidal propagation, with a shorter duration of the flood (rising tide) than the ebb (falling tide). In the long term, this contributes to the reduction of depths and the confinement of water upstream. After extensive studies, a sediment trap was created in 2011 to trap the finest sediment in the upstream part of the lagoon. This study aims to analyze the morphodynamical and sedimentological changes in the lagoon of Oualidia, after the sediment trap dredging. For this purpose, bathymetric surveys covering 6 years between 2006 and 2012 were analyzed, providing sufficient data to identify the morphological changes that the lagoon has undergone during this period. The data analysis was followed by a study of the lagoon bed dynamics using profile lines extracted from the bathymetric data in a GIS environment. As a result, the findings partly show that over 6 years, an average height of +0.65 m was gained by the lagoon, while the average change in the eroded areas was estimated to be −0.42 m. In addition, the eroded area in the lagoon was estimated to be about 1,513,800 m2 with an erosion volume of 633,383 m3, while the accumulated area found was about 2,699,396 m2 with an accumulation volume of 1,765,866 m3. These changes can be related to the large input of marine sediment, mainly caused by tidal currents and waves, but also to the creation of a sediment trap in the upstream area of the lagoon.
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Nirwansyah, A. W., i B. Braun. "ASSESSING TIDAL FLOOD UPON SOLAR SALT FARMING AREA IN NORTH PART OF JAVA USING HYDRODYNAMIC MODEL". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W8 (22.08.2019): 283–86. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w8-283-2019.
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<p><strong>Abstract.</strong> This study aims to assess the impact of high tide upon salt production areas in north part of Java, Indonesia. Single case in June 2016 was applied using MIKE 21 in salt production area of Cirebon. The inputs are tidal height records, bathymetry, digital elevation model (DEM) from Geospatial Information Agency (GIA), and wind data from OGIMET. Peak water level from tidal constituent is extracted from the simulation. The exposed that were generated from peak level of water elevation showed that tidal event has led to 82.9% of salt production area being inundated. West and east part are recorded as the most affected location due to this extreme event. The maximum water level has reached about 38 cm and covered more than 6,489.38 ha during the tide. Whilst the accurate identification will provide valuable information for flood assessment upon marginal agriculture in coastal area.</p>
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Rayo, J., J. Seriosa, J. Villa Juan i V. P. Bongolan. "ENHANCING COASTAL RESILIENCY OF HYPOTHETICAL LAND RECLAMATION SCENARIOS WITH MANGROVE FOREST AND OYSTER REEF ASSESSED BY ADCIRC AND SWAN STORM SURGE MODEL". International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVI-4/W6-2021 (18.11.2021): 243–48. http://dx.doi.org/10.5194/isprs-archives-xlvi-4-w6-2021-243-2021.
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Abstract. This study aims to assess the effectiveness of mangrove forests and oyster reefs on reducing the damages from typhoons in hypothetical land reclamation scenarios in Atimonan, Philippines. Storm surge simulations were ran using ADCIRC and SWAN coupled model on the local government unit’s (LGU) land reclamation plan and the proposed crenulate bay reclamation plan, both with concrete seawall, mangrove forests and oyster reefs. Inputs to the model include modified topography and bathymetry, coastline, land cover, typhoon Durian data and tidal potential constituents. Simulations show that the crenulate bay reclamation plan is better by 39.15% than the LGU’s land reclamation plan on reducing typhoon winds and storm surge inundation extent induced by Typhoon Durian. However, this advantage comes with an additional implementation cost of 11.02%. This study is envisioned to help the land reclamation project of Atimonan LGU to be resilient against typhoon winds and coastal inundation.
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Faizuddin, A. R. M., i M. M. Razali. "VARIATION OF CHART DATUM TOWARDS MARITIME DELIMITATION DUE TO RISING SEA LEVEL". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W5 (5.10.2017): 73–80. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w5-73-2017.
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The importance of Chart Datum in hydrographic surveying is inarguable because its determination is part of the process to obtain the actual depth of bathymetry. The Chart Datum has a relationship with the determination of base points because any uncertainty of the base points would definitely cause uncertainty to the determination of the maritime baseline. If there is any doubt on the baselines, it will then cause doubt on the maritime zones as well which includes the equidistant line that forms the border between the two countries. However, due to the ongoing rising sea level, there has been some variations of the Chart Datum in some areas in Malaysia. This research discusses about the variation of Mean Sea Level and Chart Datum for the tide gauge stations at Geting, Cendering, Sedili and Tioman at East Coast and Kukup, Langkawi, Lumut and Penang at the West Coast of Peninsular Malaysia. The tidal analysis was carried out by using the 23 years of data beginning at 1993 to 2015. The observed tidal data for 23 years were processed and analysed by using GeoTide software. In this research, the Harmonic Analysis technique was used in order to calculate the values of Mean Sea Level and the Chart Datum while the slope of the shoreline is modelled by using Global Mapper. The linear trend of the Mean Sea Level and the Chart Datum was analysed to determine the increase of the annual sea level in millimetres accuracy and also to determine the variation of the Chart Datum for each tidal station and its impact towards maritime baseline. The result has shown that the linear trend of sea level rise varies from 24 millimetres per year up to 168 millimetres per year at the East Coast and 24 millimetres per year up to 96 millimetres per year at the West Coast of Peninsular Malaysia. As for the maritime baseline, results has indicated that there exist shifting in the horizontal which are varies from 1.564 metres per year to 3.299 metres per year at the East Coast and from 1.331 metres per year up to 5.857 metres per year at the West Cost of Peninsular Malaysia. From the analysis, it can be stated that the horizontal shift occur greater at the East Coast rather than at the West Coast of Peninsular Malaysia. As a conclusion, the sea level rise does have significant impact towards maritime baseline. Furthermore, the determination of a stable Chart Datum is important to define the maritime baseline in other to avoid conflict with other neighbouring countries.
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Uda, Takaaki, Masumi Serizawa, Toshiro San-nami i Toshinori Ishikawa. "PREDICTION OF FORMATION OF DYNAMICALLY STABLE EBB TIDAL DELTA AND MEASURES FOR PREVENTING OFFSHORE SAND LOSS". Coastal Engineering Proceedings 1, nr 32 (29.01.2011): 73. http://dx.doi.org/10.9753/icce.v32.sediment.73.
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We developed a model for predicting the evolution of an ebb tidal delta based on the BG model, which was proposed by the present authors using the Bagnold concept of the equilibrium slope. Bathymetric changes around the inlet of Imagire-guchi between 1978 and 2005 were quantitatively analyzed to investigate the evolution of the ebb tidal delta and sand deposition offshore of the inlet. The model was applied to this inlet. The predicted bathymetric changes were in good agreement with the measured changes. Some measures for preventing the offshore sand loss were also considered by applying the model. The most effective measure was predicted to be cross-shore sand bypassing.
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Fofonova, Vera, Alexey Androsov, Lasse Sander, Ivan Kuznetsov, Felipe Amorim, H. Christian Hass i Karen H. Wiltshire. "Non-linear aspects of the tidal dynamics in the Sylt-Rømø Bight, south-eastern North Sea". Ocean Science 15, nr 6 (16.12.2019): 1761–82. http://dx.doi.org/10.5194/os-15-1761-2019.
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Abstract. This study is dedicated to the tidal dynamics in the Sylt-Rømø Bight with a focus on the non-linear processes. The FESOM-C model was used as the numerical tool, which works with triangular, rectangular or mixed grids and is equipped with a wetting/drying option. As the model's success at resolving currents largely depends on the quality of the bathymetric data, we have created a new bathymetric map for an area based on recent studies of Lister Deep, Lister Ley, Højer Deep and Rømø Deep. This new bathymetric product made it feasible to work with high-resolution grids (up to 2 m in the wetting/drying zone). As a result, we were able to study the tidal energy transformation and the role of higher harmonics in the domain in detail. For the first time, the tidal ellipses, maximum tidally induced velocities, energy fluxes and residual circulation maps were constructed and analysed for the entire bight. Additionally, tidal asymmetry maps were introduced and constructed. The full analysis was performed on two grids with different structures and showed a convergence of the results as well as fulfilment of the energy balance. A great deal of attention has been paid to the selection of open-boundary conditions, model validation against tide gauges and recent in situ current data. The tidal residual circulation and asymmetric tidal cycles largely define the circulation pattern, transport and accumulation of sediment, and the distribution of bedforms in the bight; therefore, the results presented in the article are necessary and useful benchmarks for further studies in the area, including baroclinic and sediment dynamics investigations.
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Salas-Monreal, David, Mayra Lorena Riveron-Enzastiga, Jose de Jesus Salas-Perez, Rocio Bernal-Ramirez, Mark Marin-Hernandez i Alejandro Granados-Barba. "Bathymetric flow rectification in a tropical micro-tidal estuary". Estuarine, Coastal and Shelf Science 235 (kwiecień 2020): 106562. http://dx.doi.org/10.1016/j.ecss.2019.106562.
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Gao, J., G. Q. Zhou, H. Y. Wang, X. Zhou, Y. X. Mu, S. H. Long i F. Yang. "LIDAR BATHYMETRIC EVALUATION BASED ON SCATTERING CLASSIFICATION ALGORITHM". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W10 (7.02.2020): 97–103. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w10-97-2020.
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Abstract. The evaluation of the bathymetric capability of traditional airborne lidar system is mostly based on the formula of bathymetric capability by evaluating the diffuse attenuation coefficient (Kd). This method is derived form the assumption that the reflectance of sediment is fixed. In this study ,however,the reflectance of sediment is not fixed. Therefore, this study improves the ability of bathymetric formula, and proposes a particle scattering classification algorithm to obtain the transmissivity value. The algorithm filters the scattering modes of particles by scattering discrimination factor (q), and obtains the transmissivity values by using the scattering intensity formulas. Experiments show that, when the transmissivity is in the range of 0–1 and the average values of Kd(532 nm) are 0.1150 m−1, 0.0894 m−1 and 0.0903 m−1 in January, June and October respectively, accordingly, the bathymetric capabilities are 0–44 m, 0–61.5 m and 0–52.5 m, respectively. Compared with the original bathymetric method, these results show that the maximum bathymetric value has measured by the improved bathymetric capability formula and scattering classification algorithm has decreased under the influence of the change of sediment reflectance, and the result is more consistent with the actual situation and more accurate.
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Zhang, Ying, Zeng Zhou, Liang Geng, Giovanni Coco, Jianfeng Tao i Changkuan Zhang. "SIMULATING THE FORMATION OF TIDAL CHANNELS ALONG AN OPEN-COAST TIDAL FLAT: THE EFFECTS OF INITIAL PERTURBATION". Coastal Engineering Proceedings, nr 36 (30.12.2018): 84. http://dx.doi.org/10.9753/icce.v36.papers.84.
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A state-of-the-art morphodynamic model (Delft3D) was used to explore the effects of bathymetric perturbation on the morphodynamic modeling of tidal channels and flats. Short-term and medium-term modeling results indicate that the two-way interaction of the hydrodynamic forcing and initial perturbation has influence on the evolution of tidal channel ontogeny. There is a critical range of the magnitude of initial perturbation, within which the morphodynamic development tends to be similar. By comparing with the case without initial perturbation, the case with a slight increase in perturbation magnitude can considerably enhance the rate of the morphodynamic development.
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Sohrt, Vanessa, Sebastian S. V. Hein, Edgar Nehlsen, Thomas Strotmann i Peter Fröhle. "Model Based Assessment of the Reflection Behavior of Tidal Waves at Bathymetric Changes in Estuaries". Water 13, nr 4 (13.02.2021): 489. http://dx.doi.org/10.3390/w13040489.
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Estuaries are often modified by human activities. Adjustments in the morphology of an estuary have a potential impact on the hydrodynamics and on the reflection behavior of the tide. The influence of such system changes on the complex tidal regime with a large number of superimposed tidal constituents is not fully understood yet. The reflection properties of estuaries that are characterized by abrupt changes in geometry are systematically investigated on the basis of simplified estuary model approaches to improve the understanding of the oscillation and reflection behavior of tidal waves in estuaries. The reflection coefficients at abrupt cross-sectional changes are determined by two different methods, i.e., an analytical energy-based approach and a hydrodynamic numerical (HN) model. Comparisons indicate a high agreement of the results of the different methods when evaluating the reflection coefficient. The tidal constituents are reflected at partial and total reflectors and amplified by shoaling depending on the water depths, the height of the bottom step and the horizontal constriction. A harmonic analysis of simulated water level data partly shows the formation and amplification of higher harmonic components as a result of shallow water effects. The interaction with reflectors results in an increasing amplification of the tidal constituents and the tide.
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Muarif, Muarif. "Karakteristik Hidrooseanografi di Perairan Pesisir Kabupaten agam". JURNAL MINA SAINS 4, nr 2 (11.01.2019): 100. http://dx.doi.org/10.30997/jms.v4i2.1549.
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The research objectives to explore the characteristic of hydrooceanography in coastal of Agam Regency. The observations parameters included physical aspecs such as bathymetric, tide, wave, water current, Transparancy, and temperature; and so chemical aspecs such as pH, salinity, dissolved oxygen, and COD. Hydrooseanographic characteristics on Agam Regency coastal described the bathymetry was shallow to deep , high wave, high tidal range, water currents dependent on season, and water quality were in good criteria to life support of aquatic biota. Key words: Hydrooceanography, wave, tidal, water quality
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Falahat, Saeed, Jonas Nycander, Fabien Roquet i Moundheur Zarroug. "Global Calculation of Tidal Energy Conversion into Vertical Normal Modes". Journal of Physical Oceanography 44, nr 12 (26.11.2014): 3225–44. http://dx.doi.org/10.1175/jpo-d-14-0002.1.
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Abstract A direct calculation of the tidal generation of internal waves over the global ocean is presented. The calculation is based on a semianalytical model, assuming that the internal tide characteristic slope exceeds the bathymetric slope (subcritical slope) and the bathymetric height is small relative to the vertical scale of the wave, as well as that the horizontal tidal excursion is smaller than the horizontal topographic scale. The calculation is performed for the M2 tidal constituent. In contrast to previous similar computations, the internal tide is projected onto vertical eigenmodes, which gives two advantages. First, the vertical density profile and the finite ocean depth are taken into account in a fully consistent way, in contrast to earlier work based on the WKB approximation. Nevertheless, the WKB-based total global conversion follows closely that obtained using the eigenmode decomposition in each of the latitudinal and vertical distributions. Second, the information about the distribution of the conversion energy over different vertical modes is valuable, since the lowest modes can propagate over long distances, while high modes are more likely to dissipate locally, near the generation site. It is found that the difference between the vertical distributions of the tidal conversion into the vertical modes is smaller for the case of very deep ocean than the shallow-ocean depth. The results of the present work pave the way for future work on the vertical and horizontal distribution of the mixing caused by internal tides.
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Kumaat, Joyce C., Kalvin S. Andaria i Denny Maliangkay. "Hydro-Oceanographic and Bathymetric Survey in Tanjung Merah as a Basis for Modelling Coastal Spatial Plans of Bitung City". E3S Web of Conferences 328 (2021): 08006. http://dx.doi.org/10.1051/e3sconf/202132808006.
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The purpose of this study was to examine the parameters of Hydro-Oceanography (Tidal and Tidal Currents) and Bathymetry (Sea Depth) in Tanjung Merah, Bitung City. The method used in this research is a field survey method. The survey was carried out at the research location, precisely in Tanjung Merah, Matuari District, Bitung City. Equipment such as GPS Fish Finder, Floater Current Meter, Tidal Pole and Boats are supporting devices in obtaining accurate data on tides, tidal currents, and bathymetry in the waters of Tanjung Merah. The results showed that the tidal current conditions at the study site with several variations in the depth of the tidal current velocity ranged from 0.2 – 0.3 cm/sec with the dominant direction of the current towards the south. While the tides using tidal harmonic analysis for 15 days of observation, the Formzal Index is 0.93 which means that the tides in this location are mixed type with a single daily trend. Bathymetric conditions in Tanjung Merah identified the topography of the bottom of the waters is steep with depth variations between 2 -30 meters along the coast of Tanjung Merah while shallow areas are found at the mouth of the Tanjung Merah river.
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Zhang, E. F., H. H. G. Savenije, S. L. Chen i X. H. Mao. "An analytical solution for tidal propagation in the Yangtze Estuary, China". Hydrology and Earth System Sciences 16, nr 9 (18.09.2012): 3327–39. http://dx.doi.org/10.5194/hess-16-3327-2012.
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Abstract. An analytical model for tidal dynamics has been applied to the Yangtze Estuary for the first time, to describe the tidal propagation in this large and typically branched estuary with three-order branches and four outlets to the sea. This study shows that the analytical model developed for a single-channel estuary can also accurately describe the tidal dynamics in a branched estuary, particularly in the downstream part. Within the same estuary system, the North Branch and the South Branches have a distinct tidal behaviour: the former being amplified demonstrating a marine character and the latter being damped with a riverine character. The satisfactory results for the South Channel and the South Branch using both separate and combined topographies confirm that the branched estuary system functions as an entity. To further test these results, it is suggested to collect more accurate and dense bathymetric and tidal information.
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Robel, Alexander A., Victor C. Tsai, Brent Minchew i Mark Simons. "Tidal modulation of ice shelf buttressing stresses". Annals of Glaciology 58, nr 74 (kwiecień 2017): 12–20. http://dx.doi.org/10.1017/aog.2017.22.
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ABSTRACT Ocean tides influence the flow of marine-terminating glaciers. Observations indicate that the large fortnightly variations in ice flow at Rutford Ice Stream in West Antarctica originate in the floating ice shelf. We show that nonlinear variations in ice shelf buttressing driven by tides can produce such fortnightly variations in ice flow. These nonlinearities in the tidal modulation of buttressing stresses can be caused by asymmetries in the contact stress from migration of the grounding line and bathymetric pinning points beneath the ice shelf. Using a simple viscoelastic model, we demonstrate that a combination of buttressing and hydrostatic stress variations can explain a diverse range of tidal variations in ice shelf flow, including the period, phase and amplitude of flow variations observed at Rutford and Bindschadler Ice Streams.
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Krien, Y., C. Mayet, L. Testut, F. Durand, A. R. Tazkia, A. K. M. S. Islam, V. V. Gopalakrishna i in. "Improved Bathymetric Dataset and Tidal Model for the Northern Bay of Bengal". Marine Geodesy 39, nr 6 (21.09.2016): 422–38. http://dx.doi.org/10.1080/01490419.2016.1227405.
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Di Silvio, Giampaolo, Chiara Dall’Angelo, Davide Bonaldo i Giacomo Fasolato. "Long-term model of planimetric and bathymetric evolution of a tidal lagoon". Continental Shelf Research 30, nr 8 (maj 2010): 894–903. http://dx.doi.org/10.1016/j.csr.2009.09.010.
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Uda, Takaaki, Yutaka Ohashi, Toshiro San-nami, Seiji Kainuma i Toshinori Ishikawa. "TOPOGRAPHIC RESPONSE TO EXTENSION OF AN OBLIQUE TRAINING JETTY AT IMAGIRE-GUCHI TIDAL INLET". Coastal Engineering Proceedings, nr 36v (31.12.2020): 47. http://dx.doi.org/10.9753/icce.v36v.papers.47.
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At Imagire-guchi tidal inlet connecting Lake Hamana to the Pacific Ocean, a jetty had been extended by 1973 to stabilize the entrance channel of the inlet. Although 45 years has passed from the completion of the extension of the jetty to 2018, large topographic changes are still occurring offshore of the tidal inlet. One of the authors investigated the topographic changes until 2005, and the beach changes around the inlet were analyzed using the BG model (a model for predicting 3-D beach changes based on Bagnold's concept). In this study, topographic changes were analyzed again using the bathymetric survey data collected by 2017, and the development and deformation of the ebb tidal delta were studied.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/V1o3QXO-q1g
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Tang, K. K. W., M. R. Mahmud, A. Hussaini i A. G. Abubakar. "EVALUATING IMAGERY-DERIVED BATHYMETRY OF SEABED TOPOGRAPHY TO SUPPORT MARINE CADASTRE". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W16 (1.10.2019): 633–39. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w16-633-2019.
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Abstract. The Department of Survey and Mapping Malaysia has introduced marine cadastre system to register the rights, other valid interests therein and ownership of spatially determined parcels in the context of the marine environment yet the implementation of the system is still at the rudimentary stage. One of the big issues here is gathering land-to-seabed data to create a seamless topographic base map to support its marine cadastre project. Seabed bathymetric mapping in coastal zone is one of the major components to support marine cadastre. In the past, accurate bathymetric measurements can be a very laborious task in hydrographic surveying. Traditional vessel-based acoustic soundings require a lot of time, operation cost and others. Today, human’s ingenuity to yield bathymetric depths from multispectral images as an alternative source to chart the seabed topography has brought in new revolution to hydrography. The paper is initiated for evaluating water depth determination by using imagery-derived bathymetry technique and check its correlation with in-situ bathymetry depths. In the course of experiment, it demonstrates a good correlation between the imagery-derived bathymetric depths and the in-situ bathymetric depths, and majority of the derived depths have passed the minimum requirement of the IHO S-44 survey standard. The result also shows that these empirical models deliver promising outcome which can be use over the turbid environment setting. Hence, imagery-derived bathymetry approach can be an efficient and repeatable way to derive the seabed topography over a huge segment of coastal region. This study also suggests that imagery-derived bathymetry approach can be recognised as an aid in seabed topographic mapping to support marine cadastre initiative.
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Zhang, E. F., H. H. G. Savenije, S. L. Chen i X. H. Mao. "An analytical solution for tidal dynamics in the Yangtze Estuary, China". Hydrology and Earth System Sciences Discussions 9, nr 2 (20.02.2012): 2213–44. http://dx.doi.org/10.5194/hessd-9-2213-2012.
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Abstract. An analytical model for tidal dynamics has been applied to the Yangtze Estuary, a large branched estuary with three-order branches and four outlets to the sea. This study shows that the analytical model developed for a single-channel estuary can also accurately describe the tidal dynamics in a branched estuary, particularly in the downstream part. For given geometry, friction, and tidal amplitude at the mouth of every branch, the tidal damping/amplification, the phase lag, the wave celerity, and the velocity amplitude along the estuary can be computed. Within the same estuary system, the North Branch and the South Branches have a distinct tidal behavior: the former being amplified demonstrating a marine character and the latter being damped with a riverine character. The satisfactory results for the South Channel and the South Branch using both separate and combined topographies confirm that the branched estuary system functions as an entity. To further test these results, it is suggested to collect more accurate and dense bathymetric and tidal information.
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Guruh Pratomo, Danar, Khomsin i Khariz Syaputra. "Comparison of Sea Surface Variation Derived from Global Navigation Satellite System (GNSS) and Co-tidal in Java Sea". E3S Web of Conferences 94 (2019): 01007. http://dx.doi.org/10.1051/e3sconf/20199401007.
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Tide represents the vertical variation of sea surface. This parameter plays important rules in bathymetric survey. The conventional method to observe the sea surface variation is by using tide pole. Nowdays, a Global Navigation Satellite System (GNSS) can be used as a means to measure the variation of sea surface as it provides high accuracy coordinates. In this research, the vertical component of GNSS was utilized to analyze the variation of sea surface. The distance between tidal stations and the survey area can be a constrain to the depth reduction because its tidal zoning. The traditional tidal zoning is a discrete model. This can be minimalized using a co-tidal chart. In this research, the vertical variation of sea surface from GNSS and co-tidal chart approachs were examined and compared to the conventional method. The comparative analysis was performed with Root Mean Square Error (RMSE). The maximum and minimum RMSE during 3 days period between the GNSS and conventional approach are 0.246 m and 0.051 m, respectively. Whereas, the maximum and minimum RMSE between the co-tidal chart model and the conventional approach at the same time are 0.286 m and 0.109 m.
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Ekpa, A. U., i N. I. Eyakndue. "Determination of a Section of Woji Riverbed Depths for Safe Navigation". Nigerian Journal of Environmental Sciences and Technology 1, nr 1 (marzec 2017): 55–68. http://dx.doi.org/10.36263/nijest.2017.01.0033.
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The depths of the oceans, seas, rivers, etc. and charting the shape and topography of the ocean floor are only determined though bathymetric processes. And mariners primarily depend on water depths beneath their vessels for safe navigation. Bathymetry also goes a long way to enhance the identification of possible features on the seabed such as elevation changes, rock outcrop, wreckages, sunken vessels, pipeline, or any other obstructions that could cause hazard to navigation. This study employs the bathymetric principles to determine river-bed depths of a section of the Woji River for the purpose of creating a two-dimensional view of the underlying sub-surface and a threedimensional model of the river-bed, to enhance safe navigation. Data acquisition was done using satellite imagery from Google Earth, total tide prediction data, sounding depths using Midas echo sounder and GPS data. Data processing performed on observed bathymetric data include spike removal, tidal correction on instantaneous depths. The processed depths were analysed and presented in form of profile view, graphs, and charts. A flow and sedimentation simulation was carried out using ArcGIS 10.3, to show the nature of the river. The tidal data aided in sounding reduction, and river average depth of 6.022m was obtained. The levelling mis-closure was 0.001m and the average variation in echo sounder calibration was 0.08m. Based on the acquired and output data, the produced chart revealed sedimentation effect on the convex coastline, uneven riverbed topography possibly due to sand excavation, which could pose serious danger to the safety of navigation. Based on these results, the use of Sub-Bottom Profiler and a Multi-Beam Echo Sounder (MBES) is therefore recommended in order to improve the quality of data obtained.
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Letard, M., A. Collin, D. Lague, T. Corpetti, Y. Pastol i A. Ekelund. "USING BISPECTRAL FULL-WAVEFORM LIDAR TO MAP SEAMLESS COASTAL HABITATS IN 3D". International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B3-2022 (30.05.2022): 463–70. http://dx.doi.org/10.5194/isprs-archives-xliii-b3-2022-463-2022.
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Abstract. Mapping coastal habitats is essential to their preservation, but the presence of water hinders seamless data collection over land-water interfaces. Thanks to its dual-wavelength and optical properties, topo-bathymetric lidar can address this task efficiently. Topo-bathymetric lidar waveforms contain relevant information to classify land and water covers automatically but are rarely analysed for both infrared and green wavelengths. The present study introduces a point-based approach for the classification of coastal habitats using bispectral waveforms of topo-bathymetric lidar surveys and machine learning. Spectral features and differential elevations are fed to a random forest algorithm to produce three-dimensional classified point clouds of 17 land and sea covers. The resulting map reaches an overall accuracy of 86%, and 65% of the prediction probabilities are above 0.60. Using this prediction confidence, it is possible to map coastal habitats and eliminate the classification errors due to noise in the data, that generate a clear tendency of the algorithm to over-estimate some classes at the expense of some others. By filtering out points with a low prediction confidence (under 0.7), the classification can be highly improved and reach an overall accuracy of 97%.
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Bolaños, Rodolfo, Jennifer M. Brown, Laurent O. Amoudry i Alejandro J. Souza. "Tidal, Riverine, and Wind Influences on the Circulation of a Macrotidal Estuary". Journal of Physical Oceanography 43, nr 1 (1.01.2013): 29–50. http://dx.doi.org/10.1175/jpo-d-11-0156.1.
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Abstract The effect of tides, river, wind and Earth’s rotation on the three-dimensional circulation in the Dee, a macrotidal estuary, are investigated using a fine-resolution model. The interactions of the large tidal amplitude, currents, river, and wind-generated circulation require baroclinic and unsteady studies to properly understand the estuarine dynamics. Assessment of the model skill has been carried out by model–observation comparisons for salinity, which is the main control for density, surface elevation, current, and turbulence. Stationary nondimensional numbers were only partially able to characterize the dynamics in this (real) complex macrotidal estuary. At low water, tidal straining and constrained river flow cause stratification. Large spatial variability occurs in the current and residual patterns, with flood-dominated maximum values occurring within the tidal channels. The tides control residual circulation by modulating stratification through tidal straining and bathymetric constraint on river flow. Tide–stratification–river interaction causes an unsteady pattern of residual circulation and tidal pulses. River-induced pulses are enhanced near low tide–inducing density-driven circulation. Wind effects are concentrated near the surface, mainly occurring at high tide because of increased fetch. Even though Coriolis has, overall, a small contribution it produces tidal pulses modifying the current and salinity distribution.
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Gesch, Dean, i Robert Wilson. "Development of a Seamless Multisource Topographic/Bathymetric Elevation Model of Tampa Bay". Marine Technology Society Journal 35, nr 4 (1.12.2001): 58–64. http://dx.doi.org/10.4031/002533201788058062.
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Many applications of geospatial data in coastal environments require knowledge of the near-shore topography and bathymetry. However, because existing topographic and bathymetric data have been collected independently for different purposes, it has been difficult to use them together at the land/water interface owing to differences in format, projection, resolution, accuracy, and datums. As a first step toward solving the problems of integrating diverse coastal datasets, the U.S. Geological Survey (USGS) and the National Oceanic and Atmospheric Administration (NOAA) are collaborating on a joint demonstration project to merge their data for the Tampa Bay region of Florida. The best available topographic and bathymetric data were extracted from the USGS National Elevation Dataset and the NOAA hydrographic survey database, respectively. Before being merged, the topographic and bathymetric datasets were processed with standard geographic information system tools to place them in a common horizontal reference frame. Also, a key part of the preprocessing was transformation to a common vertical reference through the use of VDatum, a new tool created by NOAA's National Geodetic Survey for vertical datum conversions. The final merged product is a seamless topographic/bathymetric model covering the Tampa Bay region at a grid spacing of 1 arc-second. Topographic LIDAR data were processed and merged with the bathymetry to demonstrate the incorporation of recent third party data sources for several test areas. A primary application of a merged topographic/bathymetric elevation model is for user-defined shoreline delineation, in which the user decides on the tidal condition (for example, low or high water) to be superimposed on the elevation data to determine the spatial position of the water line. Such a use of merged topographic/bathymetric data could lead to the development of a shoreline zone, which could reduce redundant mapping efforts by federal, state, and local agencies by allowing them to customize their portrayals of the shoreline using a standard baseline elevation dataset.
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Vroom, Julia, Edwin Elias, Jamie Lescinski i Zheng Bing Wang. "ASSESSMENT OF THE EFFECTS OF THE ZUIDER SEA CLOSURE ON THE HYDRODYNAMICS OF THE WADDEN SEA INLETS". Coastal Engineering Proceedings 1, nr 33 (25.10.2012): 47. http://dx.doi.org/10.9753/icce.v33.management.47.
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Large hydrodynamic and morphodynamic changes have taken place in the western Dutch Wadden Sea due to the closure of the Zuider Sea in the early 1930s. Hydrodynamic simulations for three situations, viz. just before the closure, just after the closure and at present, have been carried out in order to investigate the hydrodynamic changes since the closure and to improve our understanding of the observed morphodynamic changes. The model results show a large increase in tidal range after the closure of the Zuider Sea. This increase continued to grow after the closure due to bathymetric change and sea level rise. The morphodynamic analysis focuses on the changed behavior of the ebb-tidal deltas of the Texel Inlet and the Vlie Inlet. Both ebb-tidal deltas have undergone a re-orientation in up-drift direction. Two possible explanations based on the literature for this change are discussed with the help of the hydrodynamic simulations.
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Waterhouse, Amy F., Arnoldo Valle-Levinson i Rubén A. Morales Pérez. "Tidal asymmetries of velocity and stratification over a bathymetric depression in a tropical inlet". Continental Shelf Research 48 (październik 2012): 87–99. http://dx.doi.org/10.1016/j.csr.2012.08.002.
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Lee, Jungwoo, Bret M. Webb, Brian Dzwonkowski, Kyeong Park i Arnoldo Valle-Levinson. "Bathymetric influences on tidal currents at the entrance to a highly stratified, shallow estuary". Continental Shelf Research 58 (kwiecień 2013): 1–11. http://dx.doi.org/10.1016/j.csr.2013.03.002.
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Samat, Olivier, François Sabatier i Adrien Lambert. "Bathymetric impacts of a seawall on a micro-tidal beach, Gulf of Lions, France". Méditerranée, nr 108 (1.01.2007): 119–24. http://dx.doi.org/10.4000/mediterranee.189.
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Wachler, Benno, Rita Seiffert, Caroline Rasquin i Frank Kösters. "Tidal response to sea level rise and bathymetric changes in the German Wadden Sea". Ocean Dynamics 70, nr 8 (7.06.2020): 1033–52. http://dx.doi.org/10.1007/s10236-020-01383-3.
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Karamma, Riswal, Muhammad Saleh Pallu, Muh Arsyad Thaha i Mukhsan Putra Hatta. "Hydrodynamic Condition of Tides and Wave Diffraction in the Estuary of Jeneberang River". INTEK: Jurnal Penelitian 7, nr 1 (10.05.2020): 32. http://dx.doi.org/10.31963/intek.v7i1.2103.
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The coastal hydrodynamic pattern around the estuary is determined by the wave, river discharge, and the tidal condition which work simultaneously. The wave factor contributes to more dominant influence on estuaries located in the open sea. Wave coming towards the coast can generate current on the coast. The current pattern around the estuary is determined mainly by the magnitude of the angle formed between the incoming wave and the coastline. The objective of this research is to analyze the wave diffraction patterns and the length of tidal propagation towards the direction of the coast in the estuary. Investigated area is situated in the estuary of Jeneberang River. The analysis of tidal propagation and wave diffraction covers a reach of 4270 meters upstream. Data collected include bathymetric, wind, and tidal data. Furthermore, the result of this analysis can be used as an input in efforts to manage and develop the coastal area in the estuary of Jeneberang River. The length of the tidal propagation in the estuary of Jeneberang River is approximately 1220 meters upstream. Wave diffraction occurs from the north, northwest, and west direction. The highest wave diffraction came from the west direction with the value of 0.73 m and the lowest wave diffraction came from the north direction with the value of 0.04 m.
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Trottier, Annie-Pier, Patrick Lajeunesse, Alexandre Normandeau i Antoine Gagnon-Poiré. "Deglacial and postglacial paleoseismological archives in mass movement deposits of lakes of south-central Québec". Canadian Journal of Earth Sciences 56, nr 1 (styczeń 2019): 60–76. http://dx.doi.org/10.1139/cjes-2018-0167.
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Investigation of seismic activity in eastern Canada is important for natural hazard management as two major active seismic zones with many historical records are located in the region: the Western Québec seismic zone (WQSZ) and the Charlevoix–Kamouraska seismic zone (CKSZ), with the latter being the most active in northeastern America. This paper describes and analyses a dataset of high-resolution swath bathymetric imagery, sub-bottom profiles, and sediments cores collected in three lakes (Maskinongé, Aux-Sables, and St-Joseph) located between two active seismic zones. The geomorphology observed on high-resolution swath bathymetric imagery, the acoustic sub-bottom profiles, and the sediment analysis indicate that the lakes were disturbed by three phases of seismically induced mass movements since deglaciation: (i) during the deglacial Champlain Sea transgression and the rapid initial glacio-isostatic rebound between ∼13 and 10.5 ka cal BP; (ii) around 1180 AD; and (iii) the well-documented CKSZ 1663 AD M >7 historical earthquake. The second phase of earthquake events (1180 AD) corresponds chronologically to a previously documented large landslide in western Québec, dated at ∼1020 years BP. This earthquake is responsible for remobilizing the largest volume of sediments in the entire stratigraphic sequence of Lake Maskinongé, the westernmost lake. This earthquake was not recorded in Lake Aux-Sables and St-Joseph, which are located eastward from Maskinongé, but the largest mass movement deposits are associated with the well-known 1663 AD event of eastern Québec. Therefore, both earthquake events are interpreted to have different epicenters and the lakes of southeastern Québec recorded earthquakes from both seismic zones.
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Bermúdez-Romero, Anahí, Vanesa Magar, Markus S. Gross, Victor M. Godínez, Manuel López-Mariscal i Julio Candela. "In-Stream Tidal Energy Resources in Macrotidal Non-Cohesive Sediment Environments: Effect of Morphodynamic Changes at Two Bays in the Upper Gulf of California". Journal of Marine Science and Engineering 9, nr 4 (12.04.2021): 411. http://dx.doi.org/10.3390/jmse9040411.
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Because of the need to diversify the renewable energy matrix and because hydrokinetic tidal energy technologies are mature, many in-stream tidal energy resource studies are available globally. Still, there are many questions regarding the effect of seabed changes on tidal energy resources. For coastal regions in particular, where the seabed is generally more mobile than in deep waters, bathymetric evolution could significantly affect tidal energy production. Here, two models are used to analyse the potential effect of natural morphodynamic change on tidal energy resources at two macro-tidal sandy bays, Adaír Bay and San Jorge Bay, in the Upper Gulf of California, Mexico. One of the models is (purely) hydrodynamic, and the other is a morphodynamic model (with hydrodynamic–morphodynamic coupling). The models are validated against tidal current observations obtained with acoustic Doppler current profilers in the region of interest, using three different error statistics, which showed good agreement between models and observations. The results also showed that the most significant bed changes and the largest renewable energy resources are located near the shore. Moreover, there was a good correlation between (a) regions with the most significant depth changes and (b) the areas where the difference in annual energy production with and without depth change was largest. Finally, a two-year simulation with the morphodynamic model permitted to analyse the seabed evolution of a zonal profile off Punta Choya, the headland between the two bays. This profile evolved towards a featureless equilibrium, as expected from the morphological classification for macro-tidal sandy environments under a dominant tidal forcing. However, most importantly, this natural evolution would not be detrimental to tidal energy exploitation at the site.
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Mandlburger, G., M. Pfennigbauer, M. Wieser, U. Riegl i N. Pfeifer. "EVALUATION OF A NOVEL UAV-BORNE TOPO-BATHYMETRIC LASER PROFILER". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B1 (6.06.2016): 933–39. http://dx.doi.org/10.5194/isprs-archives-xli-b1-933-2016.
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We present a novel topo-bathymetric laser profiler. The sensor system (RIEGL BathyCopter) comprises a laser range finder, an Inertial Measurement Unit (IMU), a Global Navigation Satellite System (GNSS) receiver, a control unit, and digital cameras mounted on an octocopter UAV (RiCOPTER). The range finder operates on the time-of-flight measurement principle and utilizes very short laser pulses (<1 ns) in the green domain of the spectrum (λ=532 nm) for measuring distances to both the water surface and the river bottom. For assessing the precision and accuracy of the system an experiment was carried out in October 2015 at a pre-alpine river (Pielach in Lower Austria). A 200 m longitudinal section and 12 river cross sections were measured with the BathyCopter sensor system at a flight altitude of 15-20 m above ground level and a measurement rate of 4 kHz. The 3D laser profiler points were compared with independent, quasi-simultaneous data acquisitions using (i) the RIEGL VUX1-UAV lightweight topographic laser scanning system (bare earth, water surface) and (ii) terrestrial survey (river bed). Over bare earth the laser profiler heights have a std. dev. of 3 cm, the water surface height appears to be underestimated by 5 cm, and river bottom heights differ from the reference measurements by 10 cm with a std. dev. of 13 cm. When restricting the comparison to laser profiler bottom points and reference measurements with a lateral offset below 1 m, the values improve to 4 cm bias with a std. dev. of 6 cm. We report additionally on challenges in comparing UAV-borne to terrestrial profiles. Based on the accuracy and the small footprint (3.5 cm at the water surface) we concluded that the acquired 3D points can potentially serve as input data (river bed geometry, grain roughness) and validation data (water surface, water depth) for hydrodynamic-numerical models.
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Kostaschuk, R. A., J. L. Luternauer, J. V. Barrie, P. H. Leblond i L. Werth Von Deichmann. "Sediment transport by tidal currents and implications for slope stability: Fraser River delta, British Columbia". Canadian Journal of Earth Sciences 32, nr 7 (1.07.1995): 852–59. http://dx.doi.org/10.1139/e95-071.
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Tidal currents on the sandy, southern slope of Fraser River delta have generated dunes with heights of 0.5–3.5 m and lengths of 11–108 m. Dune geometry and migration measurements indicate net sediment transport to the northwest in the direction of flood tidal currents. Two current meters moored in the dune field showed greater frequencies of occurrence and higher mean current speeds in the flood direction compared with the ebb. Predictions from two bed-material load models indicate sediment transport is overwhelmingly dominated by flood currents. There is no obvious source of sand to replace sediment transported in the dune field, suggesting net erosion of the surface. A previous analysis of bathymetric data also shows recent erosion of the lower slope and overall slope steepening. These patterns of erosion could lead to slope failure and damage to coastal structures.
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Ono, Nobuyuki, i Satoshi Nakamura. "SAND WAVE EVOLUTION MODEL FOR EFFICIENT CHANNEL DEPTH MANAGEMENT". Coastal Engineering Proceedings, nr 36 (30.12.2018): 97. http://dx.doi.org/10.9753/icce.v36.sediment.97.
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Sand wave is a consecutive wavy bedform on seabed with several meters in wave height and several tens-hundreds of meters in wave length. If the crests of sand waves rise above the required channel depth, they often prevent vessels from safe navigation. In this study, a prediction model of sand wave evolution is applied to predict depth change at the crest of sand waves in Kanmon route, Japan. Kanmon route is a long, narrow and winding channel where strong tidal currents take place due to large tidal difference between Japan sea and Seto-island sea. In these area, a lot of bathymetric survey data have been collected to monitor the water depth. Also, channel deepening project up to -14 m is underway, and therefore reliable prediction model of sand wave evolution is needed for channel depth management in the future.
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Chen, Changsheng, Jianhua Qi, Hedong Liu, Robert Beardsley, Huichan Lin i Geoffrey Cowles. "A Wet/Dry Point Treatment Method of FVCOM, Part I: Stability Experiments". Journal of Marine Science and Engineering 10, nr 7 (28.06.2022): 896. http://dx.doi.org/10.3390/jmse10070896.
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A 3-dimensional wet/dry point treatment method was developed for the unstructured-grid Finite-Volume Community Ocean Model (FVCOM). Analytical equations were derived to examine discretized errors that occurred during the flooding/drying process by the wet/dry point treatment for the flooding/drying process. Numerical experiments were carried out for an idealized estuary, including the inter-tidal zone. The model results show that if the ratio of internal to external mode time steps (Isplit) is appropriately selected, FVCOM was capable of simulating the flooding/drying process with sufficient accuracy to ensure the mass conservation. The up-bound limit of Isplit was restricted by the bathymetric slope of the inter-tidal zone, external mode time step, horizontal/vertical resolution, and amplitude of tidal forcing at the open boundary, as well as the thickness of the viscous layer specified in the model. Criteria for time steps via these parameters were derived from these experiments, which provide a helpful guide in selecting Isplit for applying FVCOM to realistic geometric estuaries.
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Jiménez-Robles, Alfonso Miguel, Stefano Lanzoni i Miguel Ortega-Sánchez. "IMPLICATIONS OF PLUME DISCHARGE FOR TIDAL CHANNELS MORPHODYNAMICS: A COUPLED ONSHORE AND OFFSHORE SYSTEM". Coastal Engineering Proceedings, nr 35 (23.06.2017): 12. http://dx.doi.org/10.9753/icce.v35.sediment.12.
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This contribution investigates the morphodynamic equilibrium of a funnel-shaped, well-mixed tidal channel taking into account the existing dynamical coupling between the tidal channel itself and the related offshore sediment-laden plume. We use a quasi two-dimensional numerical model that resolves the fully nonlinear unsteady shallow water, sediment bed load transport and suspended sediment advection-diffusion equations along with the Exner equation for the bathymetric changes. We close this model by including a dynamic boundary condition at the channel mouth that transfers the offshore plume sediment concentration to the channel dynamics. This model reveals that the offshore plume reduces the timescales to reach equilibrium of the channel and plays a crucial role on shaping it. At equilibrium, the non-plume influence case attains a quasi-linear profile of constant slope in the seaward part. However, the bottom profile in the case that includes the offshore plume tends to increase the concavity of the bottom profile, reducing the final channel mouth depth. Finally, numerical results suggest that the plume characteristics are altered as a consequence of tidal channel evolution.
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Shaeri, S., R. B. Tomlinson, A. Etemad-Shahidi, D. Strauss i L. P. Hughes. "Hydrodynamics of a small trained tidal inlet (Currumbin Creek, Australia)". Advances in Geosciences 39 (1.04.2014): 45–53. http://dx.doi.org/10.5194/adgeo-39-45-2014.
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Abstract. Small tidal inlets are important features of coastal areas, in terms of provision of access from a back barrier water-body to the ocean as well as periodic circulation of fresh nutrients for the local ecology. Usually, dimensional and geometrical characteristics contribute significantly to morphological stability or instability of a particular inlet and necessitate an individual investigation of any desired location. In other words, generalized usage of previous empirical and experimental research of a different position can hardly be used for other places. In this regard, one of the powerful tools to understand the physical processes of a particular region is to collect as much field data as possible. Such a dataset is used to further analyse and explore the governing processes and can also be used for building a numerical computer model for supplementary studies. In this research, the results of a comprehensive field measurement at Currumbin Creek, Queensland, Australia are presented. This study is part of broader research to investigate the long term evolution of the Currumbin entrance and its adjacent beaches. Currently, an annual dredging campaign is needed to reduce the risk of flooding due to excess rainfall inundations and to maintain water quality. The majority of data were collected over a three month period consistent with the time of the 2012 dredging operation. However, due to the loss of some instrumentation, data collection for some of the parameters was repeated till the middle of May 2013. All collected data included: (1) nearshore waves and tide; (2) creek tidal variation; (3) creek flow discharge and velocity; (4) bathymetric survey of the creek; (5) beach profile evolution survey; and (6) sediment sampling. The measurement showed that the creek entrance is tidally dominated, with flood events having a major role in sediment transport into the creek. The nearshore stations' wave data illustrated the marginal effect of the beach curvature between updrift and downdrift stations. Thus, the historical dataset available from the updrift wave rider buoy will be selected to be used for future numerical modelling. Although changes of some beach profiles were comparatively insignificant, the dramatic changes of the profile lines nearby the inlet channel and also rapid bathymetric change of the flood shoal following the dredging completion are valuable information to better calibrate and interpret a local sediment modelling study for the next phase. Essentially, this evaluation needs to be considered for proposing any alternative maintenance activities.
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Zhang, Hongqiang, Daming Li, Yanqing Li, Ting Yang, Shan Luo, Shunfa Tian i Shilong Bu. "Study on Impact of Turbine Location on Hydrodynamics in Tidal Farm". Discrete Dynamics in Nature and Society 2019 (9.01.2019): 1–21. http://dx.doi.org/10.1155/2019/7983907.
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This work aims at investigating the impact of different tidal turbine locations on hydrodynamics in near-field and far-field flow; thus, three- and two-dimensional (3- & 2-D) models were exploited in combination and applied in a case study of Putuo-Hulu Islands’ tidal farm. We present a method for the simplification of tidal turbine which, based on the energy equation, determines turbine’s equivalent roughness by calculating resistance loss in flow passage. A 3-D turbine model of near-field flow in the frame of Computational Fluid Dynamics was constructed, and the flow velocity distributions in 7 combinations of “impeller rotating speed - inflow velocity” were simulated. Also a 2-D tidal model of far-field flow was established, and Finite Element Method was adopted to solve the 2-D shallow water circulation equations; thus, the impact of tidal turbine could be simulated by utilizing different location’s compositive roughness. The results show that the impact of turbine location on hydrodynamics is depending on the open degree of sea area, channel trend, and bathymetric and geographic features and that the farther distance from the turbine, the less impact on the flow field. Overall, the impact of turbine location on far-field flow is not significant, and the flow velocity varies below 8% relative to the velocity prior to turbine installation.
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Levin, E., G. Meadows, R. Shults, U. Karacelebi i H. S. Kulunk. "BATHYMETRIC SURVEYING IN LAKE SUPERIOR: 3D MODELING AND SONAR EQUIPMENTS COMPARING". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W10 (17.04.2019): 101–6. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w10-101-2019.
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<p><strong>Abstract.</strong> This paper represents the overview of hydrographic surveying and different types of modern and traditional surveying equipment, and data acquisition using the traditional single beam sonar system and a modern fully autonomous underwater vehicle (AUV) IVER3. During the study, the data sets were collected using the vehicles of the Great Lake Research Center at Michigan Technological University. This paper presents how to process and edit the bathymetric data on SonarWiz5. Lastly, it compares the accuracy of the two different sonar systems in the different missions and creates 3D models to display and understand the elevations changes. Moreover, the 3D models were created after importing the data sets in the same coordinate system. In this study, the data sets were recorded by two different sensors in the two study locations in the Keweenaw Waterway in Michigan, U.S. between the cities of Houghton and Hancock. The first one equipment is the Lowrance HDS-7 sonar on the surveying boat, and other one is the EdgeTech 2205 sonar on the fully AUV of IVER3. One of the purposes of this study is to explore the sonar post processing programs, which are very important to interpret sonar and bathymetric data, and obtained the same coordinate system of the study areas. During the project, three main processing programs were used. The first one is UnderSee Explorer 2.6, which has been used to process the data sets of Polar SV boat. Secondly, EdgeTech Discover 4600 bathymetric software used EdgeTech 2205 sonar data sets to create bathymetric files that were used in SonarWiz5. Lastly, SonarWiz5 sonar processing software can be used to process the data sets. After the data acquisition and the data process, six profiles from the first study area and the five profiles from the second study are created to compare the data sets and elevations difference. It is shown that single beam sonar might miss some details, such as pipeline and quick elevation changes on seabed when we compare to the side scan sonar of IVER3 because the single side scan sonar can acquire better resolutions to understand the 3D features, such as pipelines, reliefs etc.</p>
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Minoubi, A., M. Bouchkara, K. El Khalidi, M. Chaibi, M. Ayt Ougougdal i B. Zourarah. "IMPACT OF THE PORT STRUCTURE IN THE SPATIO-TEMPORAL EVOLUTION OF THE SEDIMENTARY AND BATHYMETRIC CHARACTERISTICS OF A MOROCCAN ATLANTIC BAY, STUDY CASE BAY OF SAFI CITY". International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVI-4/W3-2021 (11.01.2022): 215–21. http://dx.doi.org/10.5194/isprs-archives-xlvi-4-w3-2021-215-2022.
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Abstract. This study focuses on morpho-sedimentary changes in the bay of Safi (Atlantic coast of Morocco), due to a progressive extension of the port. For this purpose, several bathymetric and sedimentary surveys carried out by the Hydrographic and Oceanographic Service of the Navy (SHOM) in 1892, 1906 and 1940 respectively, coupled with a bathymetric and sedimentary measurement mission in 2009, were analyzed to understand the impact of the port developments on the bottom of Safi Bay. This analysis consists of making maps of the evolution of (i) sedimentary facies (of different dates 1892, 1906, 1940 and 2009) and (ii) the shallow seabed of the three periods 1892–1906, 1906–1940 and 1940–2009. The sedimentary facies maps show that the facies appear unstable and evolve intermittently in response to environmental changes in the bay (port construction and expansion). In addition, the overlay of the bathymetric maps indicates that the bay has undergone changes (lowering, stability, and raising) controlled by hydrodynamic conditions before, during, and even after harbor construction. Analysis of the data showed that the expansion of the port often reshaped the morphology of the bay's seabed. The consequences of these evolutions are the appearance of the fattening or the erosion of the bank and the filling of small depressions of sediments. This evolution is reflected in the modification of the funds near the port and the beach of Safi.
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Ubara, Motoki, Yusuke Uchiyama i Taichi Kosako. "Sediment Transport and Associated Long-term Bathymetric Changes due to Tidal Currents in The Seto Inland Sea, Japan". IOP Conference Series: Earth and Environmental Science 945, nr 1 (1.12.2021): 012041. http://dx.doi.org/10.1088/1755-1315/945/1/012041.
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Abstract The topography of the seafloor is essential for determining physical phenomena such as ocean currents, favorable habitats for marine organisms, optimal vessel navigation, and so on. Prevailing currents and waves, as well as associated shear stresses acting on the ocean floor, are responsible for the formation of typical topographic features including sea caldrons and sandbanks through erosion of bedrock and sediments and their deposition processes. In the Seto Inland Sea (SIS), the most extensive semi-enclosed estuary in Japan, tidal currents affect pronouncedly the formation of seafloor topographic features; however, they have not been fully studied, particularly from a hydrodynamic viewpoint. This study aims to understand bathymetric formation under the predominance of tidal currents in the SIS. A 3-D high-resolution SIS circulation model based on the JCOPE2-ROMS system in a triple-nested configuration was utilized to examine the detailed hydrodynamic processes for the topography formations. A high correlation between the bottom shear stress and the scour depth of the erosive areas was observed, demonstrating that local tidal forcing has continuously been exerted on the seafloor to erode. A diagnostic sediment budget analysis was then conducted for sediments typical of the SIS, that is, gravel, sand, and clay, using the modeled circulation field. The horizontal divergence of the residual flows indicates consistency between divergence (convergence) and erosion (deposition). The sediment budget model also shows that these sediments are generally transported from deep to shallow areas in eroded terrains to form deposited terrains fringing the eroded terrains, whereas sedimentation tendency differs largely from location to location.
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Molen, Wim van der, Holly Watson i David Taylor. "ALLOWANCE FOR FORMATION OF MEGA SAND WAVES ON THE SEABED IN THE DESIGN OF FAIRWAYS IN ESTUARIES WITH STRONG CURRENTS". Coastal Engineering Proceedings, nr 36v (28.12.2020): 35. http://dx.doi.org/10.9753/icce.v36v.sediment.35.
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The declared depth in port access channels is often maintained by dredging and monitored by regular bathymetric surveys. However, at remote sites these activities are not cost-effective and the channel depth would need to be defined based on the surveyed depth plus an allowance for sedimentation and variability in bed levels. This allowance can especially be significant in estuaries with strong tidal currents, where mega bedforms, including sand waves, develop on the seabed due to the prevailing strong current flows. The mega sand waves are highly mobile and fluctuate in height as they migrate over the seabed. Mega sand waves and mega ripples with a height up to approx. 3.2 m were observed in multi-beam bathymetric survey undertaken in the offshore entrance to the Geba River estuary in Guinea Bissau. Supramax bulk carriers with a draft of 11-12 m are planned to transit this area on departure from a proposed phosphate export terminal located further upstream in the estuary.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/5Gmy9yQkfno
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Sentchev, Alexei, Thinh Duc Nguyen, Lucille Furgerot i Pascal Bailly du Bois. "Underway velocity measurements in the Alderney Race: towards a three-dimensional representation of tidal motions". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, nr 2178 (27.07.2020): 20190491. http://dx.doi.org/10.1098/rsta.2019.0491.
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The Alderney Race, located northwest of the Cotentin Peninsula (France), is a site with high tidal-stream energy potential. Circulation through the Alderney Race is complex, with current speed exceeding 3 m s −1 at neap tide. Towed acoustic Doppler current profiler (ADCP) measurements and static point velocity measurements were performed in July 2018 focusing on assessment of circulation and vertical structure of tidal currents. Transect surveys revealed peculiar features of local dynamics such as change in location of the tidal jet on ebb and flood flow. The spatial expanse of the tidal jet was quantified and regions with largely sheared or nearly homogeneous velocity distributions were identified on the cross-sections. Velocity profiles acquired along the cross-sections were accurately characterized using a power law. The spatial variability of the power-law exponent α was found to be large and correlated with the tidal conditions. The largest variation in profile shape was observed in the northern sector and assumed to be generated by the current interaction with a bathymetric constriction. The velocity profiles were found to vary from highly sheared on flood flow to nearly homogeneous on ebb flow, with corresponding range of power-law exponent α variation from 6 to 14. In the southern sector, over a relatively smooth bathymetry, the velocity profile shape was accurately approximated using the 1/7 power law with a range of variation of α from 6.5 to 8, with respect to the tidal conditions. To our knowledge, this is the largest field survey done using towed ADCP and the results could represent a significant advance in tidal site characterization and provide advanced information to turbine developers. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race'.
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Seifi, Fardin, Xiaoli Deng i Ole Baltazar Andersen. "Assessment of the Accuracy of Recent Empirical and Assimilated Tidal Models for the Great Barrier Reef, Australia, Using Satellite and Coastal Data". Remote Sensing 11, nr 10 (22.05.2019): 1211. http://dx.doi.org/10.3390/rs11101211.
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The latest satellite and in situ data are a fundamental source for tidal model evaluations. In this work, the satellite missions TOPEX/Poseidon, Jason-1, Jason-2 and Sentinel-3A, together with tide gauge data, were used to investigate the performance of recent regional and global tidal models over the Great Barrier Reef, Australia. Ten models, namely, TPXO8, TPXO9, EOT11a, HAMTIDE, FES2012, FES2014, OSUNA, OSU12, GOT 4.10 and DTU10, were considered. The accuracy of eight major tidal constituents (i.e., K1, O1, P1, Q1, M2, S2, N2 and K2) and one shallow water constituent (M4) were assessed based on the analysis of sea-level observations from coastal tide gauges and altimetry data (TOPEX series). The outcome was compared for four different subregions, namely, the coastline, coastal, shelf and deep ocean zones. Sea-level anomaly data from the Sentinel-3A mission were corrected using the tidal heights predicted by each model. The root mean square values of the sea level anomalies were then compared. According to the results, FES2012 compares more favorably to other models with root mean square (RMS) values of 10.9 cm and 7.7 cm over the coastal and shelf zones, respectively. In the deeper sections, the FES2014 model compares favorably at 7.5 cm. In addition, the impact of sudden fluctuations in bottom topography on model performances suggest that a combination of bathymetric variations and proximity to the coast or islands contributes to tidal height prediction accuracies of the models.
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Dias, João Miguel, Francisco Pereira, Ana Picado, Carina Lurdes Lopes, João Pedro Pinheiro, Sérgio Miguel Lopes i Paulo Gabriel Pinho. "A Comprehensive Estuarine Hydrodynamics-Salinity Study: Impact of Morphologic Changes on Ria de Aveiro (Atlantic Coast of Portugal)". Journal of Marine Science and Engineering 9, nr 2 (22.02.2021): 234. http://dx.doi.org/10.3390/jmse9020234.
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Shallow coastal lagoons driven by tidal processes are extremely dynamic environments prone to continuous natural and anthropogenic pressures. The hydrodynamics of these systems deeply depends on the effect of local morphology on the tidal propagation, so their permanent evolution constantly changes tidal dependent processes. For this reason, the present work aims to review the main characteristics of Ria de Aveiro hydrodynamics, a shallow lagoon located at the Atlantic Coast of Portugal, evaluating its evolution over the last 30 years (between 1987 and 2020) and investigating the main morphological changes in its origin. For this purpose, a comparative analysis is performed to determine the main process, including the observed hydrodynamic changes: Deepening of the inlet channel or of the main lagoon channels. To achieve these goals, the authors explored a remarkable database including bathymetric, tide gauge, and salinity data from 1987 until the present. This analysis is completed by the exploitation of a hydrodynamical model (Delft3D), validated against field data. Several simulations were performed to analyse changes in tidal propagation along the lagoon channels (considering the main semi-diurnal constituent M2), tidal asymmetry, tidal currents, tidal prism, and salinity patterns. The results show that the general deepening of the lagoon observed between 1987 and 2020 led to important changes in the lagoon hydrodynamics, namely the increase/decrease of the M2 constituent amplitude/phase, as well as the increase of tidal currents and salt intrusion within the entire lagoon, with the changes being amplified towards the head of the main channels. Although the inlet deepening partially contributed to the modifications found, the results revealed that the deepening of the main lagoon channels had the most significant contribution to the changes observed during the last 30 years.
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Elias, E. P. L., A. J. F. van der Spek, Z. B. Wang i J. de Ronde. "Morphodynamic development and sediment budget of the Dutch Wadden Sea over the last century". Netherlands Journal of Geosciences - Geologie en Mijnbouw 91, nr 3 (listopad 2012): 293–310. http://dx.doi.org/10.1017/s0016774600000457.
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AbstractThe availability of nearly 100 years of bathymetric measurements allows the analysis of the morphodynamic evolution of the Dutch Wadden Sea under rising sea level and increasing human constraint. The historically observed roll-over mechanisms of landward barrier and coastline retreat cannot be sustained naturally due to numerous erosion control measures that have fixed the tidal basin and barrier dimensions. Nevertheless, the large continuous sedimentation in the tidal basins (nearly 600 million m3), the retained inlets and the similar channel-shoal characteristics of the basins during the observation period indicate that the Wadden Sea is resilient to anthropogenic influence, and can import sediment volumes even larger than those needed to compensate the present rate of sea-level rise. The largest sedimentation occurs in the Western Wadden Sea, where the influence of human intervention is dominant. The large infilling rates in closed-off channels, and along the basin shoreline, rather than a gradual increase in channel flat heights, render it likely that this sedimentation is primarily a response to the closure of the Zuiderzee and not an adaptation to sea-level rise. Most of the sediments were supplied by the ebb-tidal deltas. It is, however, unlikely that the sediment volume needed to reach a new equilibrium morphology in the Western Wadden Sea can be delivered by the remaining ebb-tidal deltas alone.
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Agrafiotis, P., D. Skarlatos, A. Georgopoulos i K. Karantzalos. "SHALLOW WATER BATHYMETRY MAPPING FROM UAV IMAGERY BASED ON MACHINE LEARNING". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W10 (17.04.2019): 9–16. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w10-9-2019.
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Abstract. The determination of accurate bathymetric information is a key element for near offshore activities, hydrological studies such as coastal engineering applications, sedimentary processes, hydrographic surveying as well as archaeological mapping and biological research. UAV imagery processed with Structure from Motion (SfM) and Multi View Stereo (MVS) techniques can provide a low-cost alternative to established shallow seabed mapping techniques offering as well the important visual information. Nevertheless, water refraction poses significant challenges on depth determination. Till now, this problem has been addressed through customized image-based refraction correction algorithms or by modifying the collinearity equation. In this paper, in order to overcome the water refraction errors, we employ machine learning tools that are able to learn the systematic underestimation of the estimated depths. In the proposed approach, based on known depth observations from bathymetric LiDAR surveys, an SVR model was developed able to estimate more accurately the real depths of point clouds derived from SfM-MVS procedures. Experimental results over two test sites along with the performed quantitative validation indicated the high potential of the developed approach.