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Nutrient concentrations in many estuaries have increased over the past century due to increases in wastewater discharge and increased agricultural intensity, contributing to multiple environmental problems. Numerous biogeochemical and physical processes in estuaries influence nutrient concentrations during transport, resulting in complex spatial and temporal variability and challenges identifying predominant processes and their rates. Mechanistic models which require these rates to quantify biogeochemical processes become complex and difficult to calibrate as the number of processes and parameters grows, owing to the high dimensionality of the parameter space and the computational cost of simultaneously modeling the transport and transformations of constituents. We developed a modeling approach that decouples transport from transformations, enabling fast, data-driven exploration of the parameter space. The approach extracted information including water age, cumulative exposure to specific habitats, and mean water depth exposure from a hydrodynamic model. Using this information, a biogeochemical model was implemented to predict ammonium and nitrate concentrations in a Lagrangian frame. The model performed each simulation in milliseconds on a laptop computer, allowing the fitting of rate parameters for key transformations by optimization. The optimization used fixed station nitrate observations and the model was then validated against high-resolution mapping observations of ammonium and nitrate. The results suggest that the observed spatial and temporal variation can be largely represented with five transformation processes and their associated rates. Dissolved inorganic nitrogen (DIN) losses occurred only in shallow vegetated areas in the model, highlighting that biogeochemical processes in these areas should be included in DIN models. [ABSTRACT FROM AUTHOR]

The relevance of assessing the applicability of intelligent wells using autonomous inflow control devices lies in the active development of the relevant sector of the oil and gas industry and the limited understanding of the economic efficiency of intelligent wells. The use of autonomous inflow control devices allows for a change in the composition of flow to the well, thus contributing to delaying the breakthrough of undesirable formation fluids, but at the same time, such an effect affects the dynamics of formation fluid production, which undoubtedly has a huge impact on the economic effect of the project. The analysis of scientific publications on the topic of "intelligent well completion" as a downhole production monitoring and remote production control system has shown that the vast majority of researchers pay attention to the evaluation of technological efficiency, ignoring the economic aspects of the proposed solutions. This study considered the dependence of the economic effect on the geological reservoir and technological well characteristics for variant 1—intelligent horizontal well (HW) completion using autonomous inflow control devices and variant 2—conventional horizontal well completion using the open hole. Calculations of production levels and dynamics in the two variants were performed on a created sector hydrodynamic model of a horizontal well operating in the depletion mode. The analysis of the obtained results allowed us to determine the applicability criteria of the proposed configuration of formation and well characteristics at the object of study, as well as to establish general dependencies of the net discounted income of an intelligent well. As a result of this study, it was determined that the economic efficiency of intelligent well completion with the use of autonomous inflow control devices relative to conventional well completion increases with decreasing permeability and drawdown pressure on the reservoir and reaches maximum values at the object of study at the thickness of the oil-saturated part of the reservoir about 5–6 m and the location of the wellbore in it at 35–40% of the thickness of the oil-saturated part below the gas–oil contact (GOC). This article covers the research gap in evaluating the economic efficiency of intelligent HW completion using AICD relative to conventional HW completion in oil rims. [ABSTRACT FROM AUTHOR]

Correctly measuring of the moments of inertia of fragments of binary fission of actinide nuclei helps solve the important problem in nuclear physics of determining the spins of such fragments. The moments of inertia are calculated using the solid rotation, hydrodynamic, and superfluid models. The best agreement with experimental data is obtained using the superfluid model with an oscillatory potential. [ABSTRACT FROM AUTHOR]

• We propose the Spatial River Recreational Index (SRRI) using a hydrodynamic model and fuzzy synthetic evaluation. • Application in the confluence of the Nakdong-Guemho Rivers highlights safety variations based on velocity, flow direction, and water depth. • The SRRI shows safe zones under various hydraulic and morphological conditions. As demands for river recreational activities increases, assessing their safety has become essential to prevent accidents. The hydraulic conditions of the river critically influence the safety of in-water activities, such as sailing, paddling, and boating. Localized hazardous areas can emerge due to the spatial variability of hydraulic phenomena. This potential risk necessitates providing information about safe zones. Therefore, this study proposes a spatial river recreational index (SRRI) to assess the safety of river recreational activities over river spaces based on hydraulic factors. We reproduce the spatial distribution of the hydraulic parameters under various discharge conditions using a 3D hydrodynamic model and then estimate the SRRI by integrating all membership degrees and weights of these parameters using fuzzy synthetic evaluation (FSE). The application of the SRRI in the confluence of the Nakdong-Guemho River, South Korea, reveals that each hydraulic parameter contributes differently to safety levels, depending on discharge and morphological conditions. Specifically, the flow direction substantially decreases safety near the river confluence, whereas the water depth plays an important role in the meandering reach of the Nakdong River. Under high-flow conditions, velocity becomes a critical factor, especially for nonpowered activities (sailing and paddling/wading). The SRRI indicates that sailing is unsafe in the main flow zone and near the river confluence due to high sensitivity to discharge changes. In contrast, paddling/wading and leisure boating are less sensitive to discharge changes, allowing these activities to be partly allowable even under high-flow conditions, except in the deep-water zones of meandering reach. These results suggest that the SRRI can assist water recreational activity users in safely engaging in river recreational activities by providing spatial safety information based on various hydraulic conditions. [ABSTRACT FROM AUTHOR]

This study aims to develop a robust and adaptable real-time forecasting system for coastal and estuarine regions, considering the challenges posed by the limited or unavailable forecast data. A real-time forecast system has been designed to handle three distinct scenarios: forecast data from global models are available, unavailable, or intermittently unavailable. To address the challenge of data unavailability, this research proposes the application of a deep learning model (DLM). This study involves the construction of a high-resolution numerical model nested within global models. The performance of the DLM is evaluated by comparing the simulation results of the nested model generated using DLM-predicted data against those obtained using data from global models. The results demonstrate a high correlation and around 90% accuracy for up to the initial 5 days of the forecast. Even in the absence of hindcast data up to 4 days prior to the forecast beginning time, the real-time forecast with DLM can achieve an accuracy exceeding 70% of the forecast data from global models. However, direct application of the developed DLM to an unknown domain results in significantly lower performance, highlighting the importance of retraining the DLM with local data. Overall, this study presents a comprehensive approach to constructing a real-time forecasting system for coastal and estuarine regions that adeptly handles various data availability scenarios through the integration of machine learning techniques. [ABSTRACT FROM AUTHOR]

ObjectiveTo improve the safety of wet-towing transportation for offshore wind power multi-bucket jacket foundations, it is necessary to explore the stability and dynamic response during the wet-towing transportation.MethodsA hydrodynamic model was constructed based on the offshore engineering analysis software MOSES, and frequency-domain analysis and time-domain analysis were performed on the wet-towing process. Quantitative analysis was also conducted on the influence of parameters such as wave loads and towing modes on the towing characteristics of the three-bucket jacket foundation.ResultsComputational results show that the three-bucket jacket foundation has good wet-towing stability, and its upright floating state can meet the intact stability checking within a draft of 8−10 m. The amplitudes of towing force, pitching angle, heaving acceleration and air pressure in the bucket of the three-bucket jacket foundation are directly proportional to the wave height, have a linear relationship with draft, and show less influence. The amplitudes of towing force and air pressure in the bucket have no obvious relationship with the wave period, but the wave period will affect the amplitudes of pitching and heaving responses the foundation. The towing force is approximately proportional to the speed squared. The pitching motion of the three-bucket jacket foundation under the conditions of the stern sea is more severe than that under the cross sea. ConclusionThe research results have important guiding significance for improving the safety of wet-towing transportation of multi-bucket jacket foundations.

Against the backdrop of rapid global climate change, the frequency and severity of storm surges in coastal areas are increasing, particularly in tidal river segments that are affected by storm surges and upstream river flooding. Although existing storm surge models have introduced a variety of different boundary settings, the boundary conditions provided are limited and cannot meet the current generalization needs of complex hydraulic engineering projects in China. This study considered the Feiyun River Basin as the research subject and coupled the upstream hydrodynamic model IFMS with the oceanic storm surge model ADCIRC. By utilizing the strengths of both models, a flood evolution model for the estuarine tidal river segment was established, enabling the spatiotemporal simulation of tidal levels in the Feiyun River tidal segment. The model not only effectively considers the impact of storm surge propagation at the estuary on flood evolution in the tidal river segment, but also the effect of upstream river flooding on the area. The study first validated the model with Typhoon Meranti in 2016, where the simulation results showed a high degree of agreement with the observed data series and errors were within acceptable limits. Flood processes at the Ruian, Mayu, Bishan Liqiao, and Dongtou tidal stations during Typhoons Doksuri and Khanun were simulated. The results show that the peak flood errors at all four stations were below 0.30 m, with Nash coefficients >0.80, indicating the model's capability to accurately reflect tidal level fluctuations and effectively contribute to disaster prevention and mitigation efforts in estuarine tidal segments. Finally, the study analyzed the impact of the driving forces of the upstream and downstream boundaries on tidal level predictions at three stations (Ruian, Mayu, and Bishan Liqiao). It was concluded that, compared to Mayu and Bishan Liqiao stations, the influence of the upstream boundary on Ruian can essentially be ignored, suggesting that the error from the upstream boundary under the influence of Typhoon Khanun is negligible for predicting errors at Ruian. The degree of the impact of the downstream boundary fluctuations on the three stations, from largest to smallest, was Ruian, Bishan Liqiao, and Mayu. Compared to the changes in the upstream boundary, the downstream boundary had a greater overall impact on all three stations. Additionally, when the downstream boundary changed by the same magnitude, the variation in low tide levels showed a decreasing trend from downstream to upstream, whereas the variation in high tide levels, although following the same trend, did not show a significant difference between the three. In summary, compared to the upstream boundary, the downstream boundary had a greater impact on tidal-level predictions at the three stations. The result shows that the lower boundary has a greater impact on the tidal level forecasts at three stations compared to the upper boundary. The study not only provides a new method for tidal river flood simulation in coastal urbanized areas but also offers directions for improving model simulation accuracy through analysis.

Floods are becoming a frequent phenomenon even in regions where floods are rare; floods in Kerala, India, are one example. The study investigates floods in the Upper Kuttanad region of Kerala, where three rivers – Pamba, Manimala, and Achenkovil – converge while some streams diverge. To tackle this challenge, two distinct scenarios, without considering diverging rivers and considering diverging rivers, are employed in a one-dimensional flood simulation of the August 2018 flood in MIKE Hydro River. The results indicate that accounting for river divergence leads to a more accurate alignment between the simulated and observed discharge with an R2 value of nearly 0.90, aiding in the comprehension of the flood characteristics. [ABSTRACT FROM AUTHOR]

In order to develop an ecological operation strategy that combines cross-basin water transfer and reservoir ecological management, this study investigates the corresponding theoretical framework and methodological approach. A novel optimization model that couples hydrodynamic with reservoir dispatch for ecological water replenishment is proposed. Using the Yongding River ecological operation project as a case study, various scenarios of Yellow River water diversion are analyzed to assess the satisfaction of ecological water demands and associated costs in the downstream channel of the Guanting Reservoir. The results show that: 1) For ideal ecological flow process, suitable ecological flow process, and minimum ecological flow process in the downstream river channel of Guanting Reservoir, the minimum values are 8.67 m3/s, 4.46 m3/s, and 1.66 m3/s respectively, and the maximum values are 49.82 m3/s, 33.69 m3/s, and 8.37 m3/s respectively. 2) The coupling model is applied to the ecological water replenishment project of Yongding River and achieves satisfying effects. The ecological guarantee degree can be increased by 48.8% when the cost of water replenishment is doubled and the Yellow River water is used for ecological water replenishment. 3) According to the water storage situation of Guanting Reservoir, the satisfaction of ecological water demand and the cost of water replenishment are comprehensively considered. In order to ensure the water supply of the Beijing section of Yongding River, two ecological water supply schemes are recommended, and the ecological guarantee degree of the two schemes can reach more than 90%. The research results provide new ideas and methods for the development of ecological water replenishment programs for Yongding River in the future, and also have important reference value for the development of ecological water replenishment programs for other water-scarce rivers. [ABSTRACT FROM AUTHOR]

To investigate the impact of temporal and spatial resolution of rainfall data on watershed flood simulation performance, the rainfall data from meteorological stations and the gridded rainfall data from meteorological forecasts for a rainfall event were adopted in this study. Interpolation methods were applied to generate rainfall processes with different spatial and temporal resolutions. A hydrodynamic model was employed to simulate the flow rates at various sections of the watershed under different rainfall scenarios. The results show that as the spatial and temporal resolutions decreased, the flood variation patterns at various sections remained consistent. Namely, the determination coefficient (R2) decreased, whereas the root means square error (RMSE) and mean absolute error (MAE) increased, and the errors in peak flow rates and the fluctuation amplitudes of the flow rates at the sections increased as well. Moreover, a decrease in temporal resolution led to a delay in the peak flow timing. Significant differences were observed between the simulation results generated from the two different rainfall datasets. The R2 values for the simulated flow rates at each section were all above 0.75 for the observed rainfall data, while 40% of the results based on meteorological forecast data were below 0.5. Overall, the simulation results using observed rainfall data outperformed those using meteorological forecast data. Through the comparative analysis of simulation results including the rainfall characteristic parameters such as the watershed-averaged precipitation (AVP) and the coefficient of variation (CV), it was found that AVP had a strong correlation with the peak flow and its increase or decrease directly affected the peak flow. On the contrary, CV showed a negative correlation with the peak flow. [ABSTRACT FROM AUTHOR]

This study aims to identify suitable sites for Corrigiola litoralis (Strapwort) using hydrological and hydrodynamic models and geographical information techniques. It was conducted on the lower Elbe River in Czechia for 1981–2020 at six research sites. Hydrological models BILAN, GR4J and TUW were used together with HEC‐RAS hydrodynamic model. In addition to hydrological model simulations, we also used observed flows. We addressed identifying sites suitable for Corrigiola litoralis by introducing conditions reflecting the ecological requirements of this species. We compared the results with the findings recorded in the literature. The accuracy of this approach was 0.750 when the source of hydrological data was the observations, and the accuracy was, on average, 0.776 when using model simulations. The determined size of a suitable area had a significant variance. The closest to the size determined from the observed data were results based on the simulation of the TUW model. The GR4J model and BILAN model overestimated the size of suitable areas. The presented approach proved to be reasonable for modelling spatio‐temporal dynamics of sites suitable for Corrigiola litoralis. [ABSTRACT FROM AUTHOR]

Tide‐dominated sandy shelf seas, such as the Dutch North Sea, are covered by sand waves. Yet, basin‐scale hydrodynamic models do not include any sand wave information because their grid sizes are too coarse to resolve sand waves individually. We explore the possibility of parametrizing the effects of sand waves on the larger‐scale tidal flow by means of a form roughness. Specifically, our aim is to see to what extent the flow over a sand wave field can be reproduced by that over a flat seabed with an increased effective roughness (accounting for both grain and form roughness). To do so, we use two process‐based hydrodynamic models: a second order perturbation approach, and Delft3D. Both models demonstrate that the presence of sand waves causes amplitude decrease and phase shift of the tidal flow. We explore the dependencies of form roughness on different sand wave characteristics (wavelength, height and asymmetry). Shorter and higher sand waves cause a higher form roughness, while our analysis does not reveal any dependency on sand wave asymmetry. Notably, the consideration of a tidal flow, characterized by several tidal constituents, each represented by an amplitude and a phase, results in a more complex form roughness analysis than in a fluvial setting, where the flow is unidirectional and steady. We thus obtain an amplitude‐based form roughness and a phase‐based form roughness, each yielding a different value, yet displaying the same qualitative dependencies. Plain Language Summary: Tide‐dominated seas, such as the Dutch North Sea, are often covered by tidal sand waves, that is, seabed undulations characterized by wavelengths of hundreds of meters, heights of several meters and migration rates of several meters per year. The presence of sand waves causes an increase in the roughness experienced by the tidal flow. As a result, the tidal flow may for example, slow down or lower in amplitude. Yet, the effects of sand waves are generally not considered in larger‐scale hydrodynamic models. We explore the possibility of representing the effects of sand waves through an increase in bed roughness on a flat seabed, that is, a form roughness. To do so, we use two process‐based hydrodynamic models. Results show that higher and shorter sand waves result in a higher form roughness. Furthermore, the unsteady nature of the tidal flow gives rise to multiple criteria to determine form roughness. These criteria yield different values for form roughness, highlighting the complexities of considering form roughness in a tidal setting. Key Points: The characteristics of tidal flow (unsteady, multiple tidal constituents) make studying form roughness more complex than in a river settingThe presence of sand waves causes amplitude decrease and phase shift of the tidal flow through an increased effective roughnessHigher and shorter sand waves result in an increased form roughness [ABSTRACT FROM AUTHOR]

Wind is a critical driving force in hydrodynamic and water quality modeling of large shallow lakes, and is characterized by the wind drag coefficient Cd, representing the momentum transfer at the air‐water interface. Contemporary empirical formulae for Cd estimation were derived over oceans and some of which are solely wind velocity U10 dependent. These formulae were previously found to be inadequate in inland lake models often resulting in the water velocity underestimation. To address this problem, a physical scale experiment was designed, in which Cd was measured using a wind profile and eddy covariance methodology. A new wind‐induced wave‐dependent Cd parameterization was also established and validated in two lake studies. The driving force was modified by the wave‐dependent Cd formula in a hydrodynamic model of the shallow Upper Klamath Lake (UKL), OR, USA. The experimental Cd was negatively correlated to the wind velocity up until the critical U10 = 1.6 m s−1 which was 1.0~3.1 times previous empirical extrapolations at light winds. The variation partitioning results showed that wave parameters contributed to more than 30% of Cd variation combined with wind parameters. The modified wind stress field was spatially heterogeneous and the modeled water velocity was closer to the observations at two sites. Significant main circulation and outer bank circulation were modeled accompanied by higher surface vorticity, compared to the original UKL model. Overall, the wave‐dependent Cd formula provided an improvement of the surface flow field in the UKL model and will improve the management of the lake ecosystems. Plain Language Summary: As a critical driving force in large shallow lakes, wind parameterization is of great importance for accurate hydrodynamic modeling. Previous wind‐dependent wind drag formulae over oceans usually generate large underestimates of water velocity in lakes. We thus propose a new wave‐dependent Cd parameterization based on an experimental study to improve the Cd parameterization in lakes. The Cd measurements were compared and confirmed by two typical methodologies of wind profile and eddy covariance. The newly derived wave‐dependent Cd parameterization was validated in two lake studies and adapted to a hydrodynamic model of the Upper Klamath Lake, OR, USA. Results showed an improved representation of the wind stress field, surface water velocity, and surface circulation. Our work should therefore be useful when using mechanistic models to manage hydrodynamics and water quality in large shallow lakes. Key Points: A wave‐dependent Cd formula was developed based on an experimental study, indicating a negative correlation of Cd with U10 at light windsSpatial heterogeneity of the wind stress field and surface circulation was identified in lake hydrodynamic modelingThe adaptation of Cd parameterization in a hydrodynamic model was improved through the wave‐dependent Cd formula [ABSTRACT FROM AUTHOR]

This study investigates the effects of the gulf stream (GS) on sea-level oscillations across various time scales and assesses the performance of a coastal and estuarine model nested within a global model in simulating these variations. It aims to improve boundary conditions to simulate sea-level oscillations more accurately by considering the influence of GS flow. An inverse correlation is observed between observed sea-level oscillation and GS flow, which becomes more pronounced over longer time scales. Using Delft3D, a high-resolution coastal and estuarine model is developed to simulate circulation dynamics in the central Indian River Lagoon (IRL), FL, and adjacent coastal areas on the Florida east coast. The model is nested into the HYCOM (Hybrid Coordinate Ocean Model), and meteorological forcings are derived from the NARR (North American Regional Reanalysis) model. The model demonstrates satisfactory performance across key parameters, including tide, salinity, water temperature, and currents. However, there remains a noticeable difference between the modeled and observed data. To address this, the model is executed with modified flow boundary conditions at eastern boundary nodes, integrating HYCOM tide, and observing low-frequency sea-level variations. The implementation of the new boundary conditions results in an improved simulation of sea-level oscillations. This study presents the conceptual framework and detailed methodologies employed in the creation of a high-resolution model tailored for estuarine and coastal areas nested into global models capable of satisfactorily simulating sea-level oscillations even when the global model does not represent GS effects. [ABSTRACT FROM AUTHOR]

The influence of cold seep methane on the surrounding benthos is well-documented but the fate of dissolved methane and its impact on water column biogeochemistry remains less understood. To address this, the distribution of dissolved methane was determined around three seeps on the south-east Hikurangi Margin, south-east of New Zealand, by combining data from discrete water column sampling and a towed methane sensor. Integrating this with bottom water current flow data in a dynamic Gerris model determined an annual methane flux of 3 x 105 kg at the main seep. This source was then applied in a Regional Ocean Modelling System (ROMS) simulation to visualize lateral transport of the dissolved methane plume, which dispersed over ~100 km in bottom water within 1 year. Extrapolation of this approach to four other regional seeps identified a combined plume volume of 3,500 km³ and annual methane emission of 0.4-3.2 x 106 kg CH4 y-1. This suggests a regional methane flux of 1.1-10.9 x 107 kg CH4 y-1 for the entire Hikurangi Margin, which is lower than previous hydroacoustic estimates. Carbon stable isotope values in dissolved methane indicated that lateral mixing was the primary determinant of methane in bottom water, with potential methane oxidation rates orders of magnitude lower than the dilution rate. Calculations indicate that oxidation of the annual total methane emitted from the five seeps would not significantly alter bottom water dissolved carbon dioxide, oxygen or pH; however, superimposition of methane plumes from different seeps, which was evident in the ROMS simulation, may have localized impacts. These findings highlight the value of characterizing methane release from multiple seeps within a hydrodynamic model framework to determine the biogeochemical impact, climate feedbacks and connectivity of cold seeps on continental shelf margins. [ABSTRACT FROM AUTHOR]

AbstractThe purpose of this paper is to develop a hydrodynamic model of two-phase, three-component fluid flow in a heterogeneous layered reservoir, taking into account cross-flow between layers, and to predict the process of oil displacement by water under conditions of water shut-off in the vicinity of injection or production wells. Numerical calculations at different water cuts (38%, 50%, 96%) showed that in the presence of cross-flow between layers, the current oil recovery coefficient of the reservoir at water shut-off in the vicinity of the producing well increases by 0.3254, 0.3067, and 0.0429 respectively, compared to water shut-off in the vicinity of the injection well. In the absence of cross-flow between layers, there is a decrease in oil recovery coefficient by 0.0082 and 0.0072 at 38 and 50% water cut, respectively. Additionally, there is an increase in recovery coefficient by 0.007 at 96% water cut. It was also obtained that in the presence of cross-flow between layers the gel washout period at water shut-off in the vicinity of the injection well is less at different water cut in 1.24–1.81 times than in the vicinity of the production well. In the absence of cross-flow between layers, the washout time at 38 and 50% water cut is almost the same, but increases by 1.084 times at 96% water cut. Comparison of results of water shut-off prediction using proposed hydrodynamic model and real data showed that calculations describe real data with an average error of about 7%. [ABSTRACT FROM AUTHOR]

Using hydrodynamic models to carry out early warning and flash floods forecasting is an essential measure for loss reduction. Nevertheless, many current hydrodynamic models lack the necessary forecasting timeliness. To address this limitation, a method combining a hydrodynamic model with the K nearest neighbours (KNN) algorithm is proposed to facilitate the rapid prediction of flash flood processes. With the rainfall sequence as the input data and the simulation results of the hydrodynamic model as the target data, the rapid forecast of water depth, water velocity and discharge are achieved. Then the Baogai Temple basin is utilized as a case study, and the rapid forecast model (RFM) is established and subjected to verification for reliability and timeliness. The results demonstrate that the established model exhibits remarkable accuracy, with 99% of the test data effectively limiting the error of accumulated inundation extent within 20%. Furthermore, the Nash-Sutcliffe efficiency (NSE) for cross-sectional discharge achieves a value of 0.98. In 75% of rainfall scenarios, both the maximum average water depth and velocity errors for the cross-sections are effectively confined to 7.5% and 10%, respectively. The model also boasts a substantial improvement in computational efficiency, enabling it to complete the prediction of the flooding process for the next 10 h within 25s. This enhancement offers valuable lead time for emergency decision-making and highlights its extensive application potential in managing flash floods. [ABSTRACT FROM AUTHOR]

With the increasing frequency of extreme convective weather, the spatial–temporal variability of rainfall becomes more diversified. As a result of the insufficient quality of rainfall monitoring data in mountainous areas, the flash flood simulation usually does not consider the effect of the rainfall center location. In this work, the GPU Accelerated Surface Water Flow and Associated Transport hydrodynamic model is used to simulate the flash flood discharge process. The effect of the rainfall center location and the basin scale on the discharge process were analyzed based on simulated data. The results show that when the rainfall center is in the upstream and midstream basins, because of gravitational potential energy conversion, the total flood volume and the flood peak discharge increase to 2–10 times, and the peak time of flash flood caused by 100 mm rainfall amount can be advanced by up to 3,000 s compared to the 20 mm rainfall amount condition. The peak discharge and the delay of peak time increase with the increase of rain peak coefficient. In addition, the increase of the basin area enhances the effect of the rainfall center location. This work is helpful to quantify the effect of the rainfall center location, which can clarify the uncertainty of flash flood simulation caused by not considering the rainfall center factor. HIGHLIGHTS When the rainfall center is in the upstream and midstream basins, the total flood volume and the peak discharge increase to about 2–10 times, the flood peak time can be advanced by 3,000 s.; The flood peak discharge increases with the increase of the rain peak coefficient, while the delay of the flood peak time is longer.; The increase of the basin area enhances the effect of the rainfall center location on flash flood.;

There was an increase in the groundwater level and increased waterlogging of the terrain at the "Šaški potok" flotation tailing dump in Majdanpek, due to a damage of drainage collector. The stability of man-made materials of the landfills is directly dependent on the position of the free water surface in the body of the landfill. The rise of the underground water level leads to a decrease in the strength parameters of the materials from which the dam is built, which reduces the safety factor of the outer slope. For the purpose of interventional lowering the high level of underground water in the main dam body of the landfill, a hydrodynamic terrain model was created and various conceptual solutions were evaluated, using the hydrodynamic analysis. A group of wells was selected as the most optimal technical solution for lowering the groundwater level below the designed elevation.

Pathogen dispersal from infected aquaculture sites into the surrounding ocean poses risks of infection to wild and farmed species, but is difficult to predict. This study aimed to build a framework using an ocean circulation and a particle tracking model in conjunction with a dynamic infection model and a virus inactivation model to simulate the dispersal of the infectious salmon anemia virus (ISAV) from Atlantic salmon farms. Simulated particles were released from hypothetically infected farms and advected by modelled currents. Inactivation of viral cohorts by ambient ultraviolet radiation and natural microbial communities was simulated during advection. Simulations showed that ISAV concentration varied spatiotemporally with the progression of the outbreak, current speed and direction, tidal elevation amplitude, and environmental decay. Connectivity among aquaculture sites varied in relation to seaway distances, though simulations showed that connectivity can also be asymmetrical between farm sites. Sensitivity analyses showed that the dispersal of ISAV was moderately sensitive to uncertainty associated with the viral decay model, highlighting the importance of obtaining accurate estimates of inactivation rates of ISAV. This framework provides an approach to simulate waterborne viral transmission that considers the biology and epidemic features of significance for pathogens and the dynamic conditions of the ocean.

Estimating ecological environmental flow in tidal rivers is one of the major challenges for sustainable water resource management in estuaries and river basins. This paper presents an ecological environmental flow framework that was developed to accommodate highly dynamic medium tidal estuaries found along the Yellow Sea coast of China. The framework not only proposes a method of water quality-based ecological flow for tidal gate-controlled rivers but also proposes a method of water demand for scouring and silting to protect ports in coastal viscous sediment environments. The framework integrates the instream water requirements of water quality, sediment and basic ecological flow, and considers the temporal and spatial variation differences for the environmental flow requirements of tidal rivers. This study emphasizes the significance and necessity of continuous monitoring of ecological data in determining the environmental flow of tidal rivers. The output of this study could provide vital references for decision-making and management of the water resource allocation and ecological protection in tidal rivers. HIGHLIGHTS This study develops an ecological environmental flow framework for highly dynamic medium tidal estuaries.; This study suggests a method of water quality-based ecological flow for tidal gate-controlled rivers.; This study proposes a method of water demand for scouring and silting.;

The response capacities of urban flood forecasting and risk control can be improved by strengthening the computational abilities of urban flood numerical models. In this work, a GPU-based hydrodynamic model is developed to simulate urban rainstorm inundations. By simulating rainstorm floods in a certain area of Xixian New City, the established model can implement high-resolution urban rainstorm inundation simulations with significantly accelerated computing performances. The accelerated computation efficiencies of the different rainstorm event simulations under resolutions of 5 and 2 m are quantitatively analysed, showing that the absolute and relative speedup ratios for all scenarios of applying two GPUs range from 10.8 to 12.6 and 1.32 to 1.68 times as much as those of a CPU and a single GPU, respectively. The application of a large-scale rainstorm inundation simulation shows the excellent acceleration performance of the model compared to previous research. In addition, the greater the number of computational grids included in the simulation, the more significant the effect on the acceleration computing performance. The proposed model efficiently predicts the spatial variation in the inundation water depth. The simulation results provide guidance for urban rainstorm inundation management, and they improve the time and efficiency of urban flood emergency decision-making. HIGHLIGHTS The GPU-based hydrodynamic model is used to evaluate sponge city rainstorm inundation.; Significant speedup of the model executed on multi-GPU compared to a single GPU.; The model is efficient for performing high-resolution sponge city inundation simulation.; Validation and speedup computing performance tests on real urban city-scale areas.;

Estuaries worldwide are of substantial ecological value due to the presence of various gradients, such as salinity. Preserving the natural value of estuaries is vital for meeting the climate stabilization goals of the Paris Agreement. Recognizing nature as a stakeholder is imperative, given the surpassing value of ecosystem services over global gross domestic product. Quantifying the current ecological state and future ecological shifts faces challenges, including variable dependencies, spatial-temporal disparities, and the limitations in available information. This study introduces EMMA (Ecotope-Map Maker for Abiotics), a method for quantifying the effects of human interventions or climate change scenarios on estuarine ecosystems by linking abiotic characteristics derived from a hydrodynamic model to ecotopes. The Western Scheldt, an estuary connecting the Scheldt river to the North Sea in the Netherlands, serves as a case study. The method successfully reproduced an existing ecotope-map, which is dependent on real-time data such as aerial photographs. The developed method not only proves applicable in assessing the current ecological state and future ecological shifts for hypothetical scenarios but also demonstrates utility in predicting future situations, providing valuable insights for decision-makers in estuarine ecosystem management and contributing to climate and environmental preservation goals.

Numerous sudden water pollution (SWP) incidents have occurred frequently in recent years, constituting a potential risk to human, socio‐economic, and ecological health. This paper systematically reviews the current literature, with the view to establishing a management framework for SWP incidents. Only 39 of the 327 downloaded articles were selected, and the ROSES protocol was utilized in this review. The results indicated industries, mining sites, and sewage treatment plants as key SWP contributors through accidental leakages, traffic accidents, illegal discharge, natural disasters, and terrorist attacks. These processes also presented five consequences, including the contamination of drinking water sources, disruption of drinking water supply, ecological damage, loss of human life, and agricultural water pollution. Meanwhile, five mitigation strategies included reservoir operation, real‐time monitoring, early warning, and chemical and biological treatments. Although an advancement in mitigation strategies against SWP was observed in this review, previous studies reported only a few prevention strategies. Considering that this review provided an SWP‐based management framework and a hydrodynamic model selection guideline, which provide a foundation for implementing proactive measures against the SWP. These guidelines and the SWP‐based management framework require practical field trials for future studies. Practitioner Points: Sudden water pollution increases with industrial growth but decrease with awareness.Human and ecosystem health and social economy are the endpoint receptacles.Mitigation strategies include reservoir dispatch, early warning, and treatments.DPSIR model forms the basis for proving proactive measures against sudden pollution.This review provides a guideline for the selection hydrodynamic models application. [ABSTRACT FROM AUTHOR]

The work describes the possibility of using a conducting fluid model (single-fluid model) to analyze physical phenomena observed in the inhomogeneous gas discharge plasma. A technique for calculation of the heat fluxes and temperature fields in a discharge in a cylindrical glass tube with metal sections is proposed. The presence of metal sections leads to a change in the thermal balance in the plasma volume. Specific calculations have been carried out for conditions with significantly different thermal conductivity coefficients of gases (argon and helium) and metals (steel and copper). Two cases of the discharge state—diffuse and constricted—are considered. Spatial distributions of heat sources, temperature fields and heat fluxes depending on the gas type, and discharge tube configuration are presented. The considered discharge configuration and the proposed calculation method can be useful for practical applications, for example, in laser physics. [ABSTRACT FROM AUTHOR]

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Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study examines the hydrodynamic regimes in Shediac Bay, located in New Brunswick, Canada, with a focus on the breach in the Grande-Digue sand spit. The breach, which was developed in the mid-1980s, has raised concerns about its potential impacts on water renewal time and water quality in the inner bay. The aims of this study, using mathematical modeling approaches, were to evaluate the flow regimes passing through the breach and influences on the distribution of dissolved matter, providing insights into whether the breach should be allowed to naturally evolve or be artificially infilled to prevent contaminant stagnancy in the bay. The study considered three simulation scenarios to comprehend the water renewal time and the role of the breach in the environmental management of Shediac Bay. Results indicated that completely closing the breach would significantly increase the water renewal time in the inner bay, although the spatial extent of this increase is limited. However, the study identified some limitations, including the need to better define the concentration limit for considering water as renewed and the lack of consideration of dynamic factors such as wind and wave effects. [ABSTRACT FROM AUTHOR]

In this paper, we study the well-posedness, ill-posedness and uniqueness of the stationary 3-D radial solution to the bipolar isothermal hydrodynamic model for semiconductors. The density of electron is imposed with sonic boundary and interiorly subsonic case and the density of hole is fully subsonic case. It is difficult to estimate the upper and lower bounds of the holes due to the coupling of electrons and holes and the degeneracy of electrons at the boundary. Thus, we use the topological degree method to prove the well-posedness of solution. We prove the ill-posedness of subsonic solution under some conditions by direct mathematical analysis and contradiction method. The ill-posedness property shows significant difference to the unipolar model. Another highlight of this paper is the application of specific energy method to obtain the uniqueness of solution in two cases. One case is the relaxation time τ = ∞ , namely, the pure Euler-Poisson case; the other case is j τ ≪ 1 , which means that, when the current flow is sufficiently small and the relaxation time is sufficiently large both can satisfy. [ABSTRACT FROM AUTHOR]

Deception Island is an active volcano with a submerged caldera open to the sea called Port Foster. Several post-caldera-collapsed volcanic events, as well as hydrodynamics, have changed its inner coastline, shaping new volcanic deposits. A hydrodynamic model is presented to predict accretion and erosion trends in this bay, which could have an impact on the mobility of researchers and tourists. New historical orthophotos and spatio-temporal differences between digital elevation and bathymetric models were used for validation purposes. The model reveals that the south-facing coast is more susceptible to erosion, while the east- or west-facing coast experiences sedimentation. A visual study for the periods 1970–2003 and 2003–2020 in Port Foster obtained similar annual erosion/accretion lineal rates (0.3–2 m/year) in the areas not affected by the last eruptive period, as well as increases of 0.023 km2/year and 0.028 km2/year of the inner bay and coastal sedimentation rates of 0.007 km2/year and 0.002 km2/year, respectively. Only part of the significant total volume loss is received within the bay, including its own erosion, and accumulates on the bay bottom. This is largely because the volume input is composed of snow, and it is also due to the transfer of material outside to balance the figures. [ABSTRACT FROM AUTHOR]

A model simulating the complex marine dynamics along the central-eastern coast of Tunisia is set up aiming at its application to coastal management and conservation studies. The model includes a zoom on the Bay of Monastir in the centre of the domain, a coastal area that suffers from environmental problems exacerbated by the intense economic activities it hosts. Model validation was performed using observational and analysis data. The model closely reproduces the main hydrodynamic characteristics of the water masses in relation to the complex bathymetry of the area and the effects of the large scale circulation, in particular the intrusion of the water masses of Atlantic origin. The seasonal variability and the effects of particular events as heavy precipitation episodes were also studied using the principal component analysis. It is concluded that the high resolution of the model allows a fine analysis of the water movements in particular in and around the Bay of Monastir which acts as a barrier to the water flow on the larger scale. As an application, the particle transport module included in the model was used to test the dispersion of matter along the coasts and offshore. It is shown that the release of particle-charged water when currents are directed offshore can improve the dispersion of particles away from the coasts, thus enabling better environmental conditions for the region. [ABSTRACT FROM AUTHOR]

This study presents the adaptation of a torus-shaped prime mover of a wave energy converter to an onshore or nearshore fixed platform by a hinged arm, with the objective of providing more favorable conditions for device survivability at extreme sea state. An optimization code is developed to obtain the best prime mover and arm geometries, as well as the power take-off parameters, with the objective to maximize the total absorbed power. In this paper, the power take-off system is modeled as a simplified damper and spring system, where the parameters are optimized for the power absorption of the wave energy converter in each sea state, whereas the optimization process is performed with a genetic algorithm. The results indicate that better survivability performance may be achieved with the torus-shaped prime mover in comparison to a conventional one without a moonpool, despite a relatively lower wave-absorbed power. [ABSTRACT FROM AUTHOR]

We investigated the seasonal variation in the current field in Harima-Nada using a high-resolution three-dimensional numerical model. The model showed sufficiently good performance at recreating its spatial and seasonal variation. Additionally, the model successfully reproduced the observed temperature and salinity patterns and values, as well as the observed surface current fields. The seasonal variation was consistent with previous studies, showing downwind circulation in winter induced by northwesterly winds and cyclonic circulation in summer induced by density-driven circulation. The water was well-mixed during winter and stratified in summer. During summer, a bottom cold water (BCW) dome develops beneath the thermocline in the central basin, where a surface cyclonic eddy occurs. Cold water from the previous winter is trapped at the bottom in topographic depressions after the onset of spring, forming BCW in the Harima-Nada (HNBCW). Meanwhile, pressure gradients associated with the density difference across the BCW drive geostrophic flow and form a cyclonic eddy at the surface above the HNBCW. HNBCW experiences a temperature increase of approximately 12.8 °C from spring to summer, which is associated with vertical diffusion and horizontal advection processes. Air–sea heat flux is the main factor influencing water temperature and its changes in the HNBCW. In addition, topographic features and river discharge factors affected water circulations as well as the formation and variation in the HNBCW. Harima-Nada is a small, shallow semi-enclosed coastal sea, and therefore any small change in these dynamic factors can affect water characteristics. [ABSTRACT FROM AUTHOR]

River flood routing computes changes in the shape of a flood wave over time as it travels downstream along a river. Conventional flood routing models, especially hydrodynamic models, require a high quality and quantity of input data, such as measured hydrologic time series, geometric data, hydraulic structures, and hydrological parameters. Unlike physically based models, machine learning algorithms, which are data-driven models, do not require much knowledge about underlying physical processes and can identify complex nonlinearity between inputs and outputs. Due to their higher performance, lower complexity, and low computation cost, researchers introduced novel machine learning methods as a single application or hybrid application to achieve more accurate and efficient flood routing. This paper reviews the recent application of machine learning methods in river flood routing. [ABSTRACT FROM AUTHOR]

Simulating river–lake systems while accounting for climate change and human activity is challenging, particularly when dealing with the complex interactions between rivers and lakes. In this study, we developed an integrated model coupling long short-term memory (LSTM), a two-dimensional hydrodynamic model (NewFlood), and the time-variant gain model (TVGM). We applied and validated this model using the Yangtze River–Poyang Lake system. The coupled model accurately and efficiently simulated the water levels, streamflow, and water exchange between the Yangtze River and Poyang Lake. The average Nash-Sutcliffe efficiency coefficient of the coupled model reached 0.92, indicating high simulation accuracy. The coupled model holistically accounts for the impacts of climate change and human activities on the spatiotemporal dynamics of river–lake systems, providing a robust scientific basis for quantifying the relative contributions of different factors influencing river–lake interactions. [ABSTRACT FROM AUTHOR]

To help determine whether planktonic eggs of fishes on the West Florida Shelf (WFS) are retained locally or exported elsewhere, we collected fish eggs by plankton net from 17 locations (stations) and identified them using DNA barcoding. We then entered the station coordinates into the West Florida Coastal Ocean Model (WFCOM) and simulated the trajectories of the passively drifting eggs over 2 weeks at three depths (surface, midwater, and near bottom). The results indicated there were two groups of trajectories: a nearshore group that tended to be retained and an offshore group that tended toward export and potential long‐distance dispersal. We also found evidence of a relationship between retention and higher fish‐egg abundance; nearshore stations were associated with higher fish‐egg abundances and higher retention. We suggest this is the result of (1) increased spawning in high‐retention areas, (2) increased drift convergence in high‐retention areas, or both processes acting together. Community analysis using SIMPROF indicated the presence of a depth‐related (retention‐related) difference in species assemblages. Fish‐egg species were also categorized as pelagics or non‐pelagics; there was no evidence of pelagic species being more likely to be exported. [ABSTRACT FROM AUTHOR]

Spatial heterogeneity or "patchiness" of plankton distributions in the ocean has always been an attractive and challenging scientific issue to oceanographers. We focused on the accumulation and dynamic mechanism of the Acetes chinensis in the Lianyungang nearshore licensed fishing area. The Lagrangian frame approaches including the Lagrangian coherent structures theory, Lagrangian residual current, and Lagrangian particle-tracking model were applied to find the transport pathways and aggregation characteristics of Acetes chinensis. There exist some material transport pathways for Acetes chinensis passing through the licensed fishing area, and Acetes chinensis is easy to accumulate in the licensed fishing area. The main mechanism forming this distribution pattern is the local circulation induced by the nonlinear interaction of topography and tidal flow. Both the Lagrangian coherent structure analysis and the particle trajectory tracking indicate that Acetes chinensis in the licensed fishing area come from the nearshore estuary. This work contributed to the adjustment of licensed fishing area and the efficient utilization of fishery resources. [ABSTRACT FROM AUTHOR]

With the development and popularity of advanced RISC machines(ARM), adapting the X86-based scientific computing software to ARM-based computing platforms is one of the key issues for scientific research and operational applications. It is urgent to explore the software-hardware-adaptation methods of advanced RISC machines for professional computational models. This paper systematically analysed the key points for software hardware adaptation of ARM. By comparing the existing software adaptation technologies, it selected container technology to enable the hydrodynamic model to run on ARM-based computing platforms. Container technology could package the application software and its dependencies into a portable container, which made the suggested software run freely without any dependency on the underlying architecture and operating system. Taking the hydrological hydrodynamic model, TELEMAC, as an example, it explained the principle of Docker image composition in detail, and built the TELEMAC image environment through Dockerfile. The method was verified by carrying out the computational cases. The results show that the TELEMAC image can run safely on the Kunpeng 920 processor-based openEuler and Kirin V10. The case calculation results are consistent with the standard results, and the model calculation efficiency is high. The proposed method realizes the adaptation from an X86-based platform to ARM-based computing platforms for professional scientific computing models. This study can also provide a reference for the localization adaptation of other software. [ABSTRACT FROM AUTHOR]

The evolution trend of wireless communication systems tends to ultra-high data rate, ultra-low latency, and high bandwidth systems. It is foreseen that 6G wireless communication systems will be developed in the range of 100–300 GHz (upper mmWave band) and 300–3000 GHz (terahertz band). In such frequencies, the performance of junctionless field effective transistors is limited due to the reduction of carrier mobility in the device channel. In this paper, for the first time, a shell doped device is proposed to improve RF merit parameters and high-frequency noise performance of GaN junctionless double surrounding nanotube FET device with dual material outer gate (SD-GaN-JNFET). Simulation results show that the doping engineering in the proposed device reduces scattering caused by phonon and doping and increases electron mobility significantly. Parameters gmmax and ƒT of the SD-GaN-JNFET device in channel length of 15 nm are 666 μS and 8.47 THz, respectively, and NFmin<0.025 dB is satisfied in the frequency range of 0-500 GHz. The effect of shell doped area on the linearity performance is evaluated. Moreover, the device shows excellent reliability in terms of trap charges. A non-quasi-static small signal model is developed for the device and incorporated into a low noise amplifier (LNA) design. The LNA with S21 = 22.10 dB and NF = 0.032 dB in central band frequency (140 GHz) was attained. This article opens up an opportunity to achieve high-performance LNA for D-Band 6G applications with the reliable SD-GaN-JNFET device. [ABSTRACT FROM AUTHOR]

The interactions of charged particles moving paraxially in multi-walled carbon nanotubes may excite electromagnetic modes. This wake effect has recently been proposed as a potential novel method of short-wavelength high-gradient particle acceleration and for obtaining brilliant radiation sources. In this work, the excitation of wakefields in double-walled carbon nanotubes is studied by means of the linearized hydrodynamic theory. General expressions have been derived for the excited longitudinal and transverse wakefields and related to the resonant wavenumbers which can be obtained from the dispersion relation. In the absence of friction, the stopping power of the wakefield driver, modelled here as a charged macroparticle, can be written solely as a function of these resonant wavenumbers. The dependencies of the wakefields on the radii of the double-walled carbon nanotubes and the driving velocity have been studied. Double-walled carbon nanotubes with inter-wall distances much smaller than the internal radius may be a potential option to obtain higher wakefields for particle acceleration compared to single-walled carbon nanotubes.

The influence of cold seep methane on the surrounding benthos is well-documented but the fate of dissolved methane and its impact on water column biogeochemistry remains less understood. To address this, the distribution of dissolved methane was determined around three seeps on the south-east Hikurangi Margin, south-east of New Zealand, by combining data from discrete water column sampling and a towed methane sensor. Integrating this with bottom water current flow data in a dynamic Gerris model determined an annual methane flux of 3 x 105 kg at the main seep. This source was then applied in a Regional Ocean Modelling System (ROMS) simulation to visualize lateral transport of the dissolved methane plume, which dispersed over ∼100 km in bottom water within 1 year. Extrapolation of this approach to four other regional seeps identified a combined plume volume of 3,500 km3 and annual methane emission of 0.4–3.2 x 106 kg CH4 y-1. This suggests a regional methane flux of 1.1–10.9 x 107 kg CH4 y-1 for the entire Hikurangi Margin, which is lower than previous hydroacoustic estimates. Carbon stable isotope values in dissolved methane indicated that lateral mixing was the primary determinant of methane in bottom water, with potential methane oxidation rates orders of magnitude lower than the dilution rate. Calculations indicate that oxidation of the annual total methane emitted from the five seeps would not significantly alter bottom water dissolved carbon dioxide, oxygen or pH; however, superimposition of methane plumes from different seeps, which was evident in the ROMS simulation, may have localized impacts. These findings highlight the value of characterizing methane release from multiple seeps within a hydrodynamic model framework to determine the biogeochemical impact, climate feedbacks and connectivity of cold seeps on continental shelf margins.

Autonomous underwater vehicle (AUV) equipped with ducted propellers exhibit increased maneuverability. However, ducting also influences the AUV's dynamic characteristics. Accordingly, it is crucial to analyze the effect that ducted propellers exert on an AUV's hydrodynamic performance. This paper utilizes computational fluid dynamics (CFD) to study this impact. Firstly, two AUV models with identical geometry except for the presence of ducted propellers were constructed using 3D software. Subsequently, two sets of overlapping grids for the CFD hydrodynamic analysis were created, each for one of the AUVs. Hydrodynamic coefficients for both models were obtained by calculating their translational and rotational motions, and differences between these coefficients were analyzed to evaluate the ducted propellers' effect. The computational results reveal that ducted propellers augment the inertial hydrodynamic forces in surge motion while reducing those in sway, heaven, pitch, and yaw motions. In addition, the presence of ducted propellers heightens the viscous hydrodynamic forces during translational motion and diminishes them during rotational motion. The ducted propeller further impacts the AUV's streamlined shape, thereby altering the AUV's inertial and viscous hydrodynamic characteristics. Therefore, when designing AUV with ducted propellers, it is critical to consider the effect of ducting on the AUV.

Satellite altimetry (SA) is one of the most valuable techniques that measure the sea level data at both the near-coast and offshore. There exists, however, multiple challenges and hindrances in determining and using accurate sea level data. The most pertinent is that evaluation of SA performance requires that all data sources (such as tide gauges (TG) and hydrodynamic models (HDMs)) refer to the same vertical datum. Thus, knowledge of the geoid (equipotential surface of the earth) is essential in linking different sources of sea level. Accordingly, this study examines performance of along-track data for three satellite missions (Sentinel-3A, Jason-3, and Sentinel-6A) to obtain realistic sea level variation and to determine the accuracy of the various missions in the complex area of the eastern Baltic Sea. The methodology consisted of utilizing SA, HDM, and TG data and a high-resolution geoid model. Results show that root-mean-square error (RMSE) varied for Jason-3 within a range of 1.68–50.14 cm, Sentinel 3A with a range of 2.8–46.27 cm, and Sentinel 6A with a range of 3.5–43.90 cm. Sentinel 6A was determined to be the most accurate and reliable satellite mission. Results also showed higher RMSE (15.7–46.2 cm) during (i) the seasonal sea ice month (e.g. March 2018); (ii) at locations of several islands (e.g. eastern section of Gulf); and (iii) at locations where rivers discharged into the Gulf (e.g. Nava, Kemi, Luga, and Neva rivers). These features tended to show up as peaks in the final results even though robust data processing for outliers were undertaken. These results suggests that improvements can still be made in the SA retrackers and also in the data-processing techniques utilized.

This study aims to develop a robust and adaptable real-time forecasting system for coastal and estuarine regions, considering the challenges posed by the limited or unavailable forecast data. A real-time forecast system has been designed to handle three distinct scenarios: forecast data from global models are available, unavailable, or intermittently unavailable. To address the challenge of data unavailability, this research proposes the application of a deep learning model (DLM). This study involves the construction of a high-resolution numerical model nested within global models. The performance of the DLM is evaluated by comparing the simulation results of the nested model generated using DLM-predicted data against those obtained using data from global models. The results demonstrate a high correlation and around 90% accuracy for up to the initial 5 days of the forecast. Even in the absence of hindcast data up to 4 days prior to the forecast beginning time, the real-time forecast with DLM can achieve an accuracy exceeding 70% of the forecast data from global models. However, direct application of the developed DLM to an unknown domain results in significantly lower performance, highlighting the importance of retraining the DLM with local data. Overall, this study presents a comprehensive approach to constructing a real-time forecasting system for coastal and estuarine regions that adeptly handles various data availability scenarios through the integration of machine learning techniques.