This study assesses the feasibility of a beach and dune system as flood defense against storm surge along the coastlines of the Houston-Galveston area, proposed as a part of the Coastal Texas Project. We apply a semiempirical analytical model to predict dune erosion in a dual-dune system under changing climate conditions. Synthetic storms were simulated using validated hydrodynamic, wave, and hurricane models to produce input data (storm surge, wave height, and period) for the dune erosion model, reflecting both present day and future climate scenarios that incorporate projected sea level rise (SLR). Bias-correction techniques were applied to climate model output using historical observations of storm surge and wave data. An alternative sampling approach was also developed to stochastically predict dune erosion by integrating synthetic data into a copula-based framework. Results indicate that the annual-average dune erosion is approximately 8%-10% of system volume in the present scenario and increases to 33%-40% in future scenarios with higher SLR, leading to estimated dune rehabilitation cycles of 8-10 and 2-2.5 years, respectively. These findings suggest that, although the proposed beach and dune system is likely to be effective for storm surge protection under the present climate condition, significant adjustments will be desirable to maintain its resilience in the face of evolving climate and sea level rise. Importantly, bias correction of input data yielded substantial reductions in predicted storm surge and significant wave height, resulting in more accurate dune erosion predictions. This demonstrates the necessity of bias correction of hydrodynamic and wave parameters derived from global climate simulations for reliable coastal risk assessment and future planning. The copula sampling approach produced results comparable to the original results, which considered storms with extremely low or high occurrence probabilities, while providing lower sensitivity to bias-correction methods and copula generator types.

The Ike Dike is a concept of coastal barrier system designed to protect the Houston-Galveston area (HGA), which is highly susceptible to flood risks from storm surges. The barrier system has been proposed with different alignments and configurations: movable, permanent, and extended permanent barrier systems. We have evaluated and compared the feasibility of three barrier types as a function of sea level rise (SLR), taking into account the reliability of the movable barrier. We employ the Delft3D Flexible Mesh suite to simulate storm surges in a hydrodynamic model, incorporating pressure and wind velocity fields spatialized by the Holland’s model from synthetic storm tracks. Simulations are driven by a range of SLR projections and synthetic storm tracks, with different barrier types. Probabilistic flood depths are predicted for specific return periods by fitting the 30-year maxima flood depths from the simulations to a probability distribution function. Using the CoreLogic database of residential properties in the HGA and building damage functions, we calculate probabilistic flood damages for each predicted flood depth. This allowed us to quantify flood risk as the expected annual damage, integrated over a range of return periods. Our results indicate that the permanent and extended permanent barrier systems are more effective at mitigating storm surge risk than the movable barrier system. Moreover, the necessity of the extended permanent barrier system becomes more significant as SLR increases.

Land subsidence is a significant issue in many coastal megacities, including Shanghai, where it poses risks to infrastructure and economic stability. Although numerous studies have used SAR datasets to monitor land subsidence in Shanghai, multi-decadal displacement measurements obtained from multi-sensor SAR data remain unavailable. Moreover, the contributions and variations of driving factors behind the evolution of land subsidence remain poorly understood. This study employs multi-sensor SAR fusion method and a Random Forest model, along with Shapley Additive exPlanations (SHAP), to examine subsidence evolution and assess the influence of key drivers over the past 30 years. The results show that severe subsidence has spread from central urban areas to surrounding suburban regions, particularly in the eastern coastal and southern industrial zones in Shanghai. SHAP analysis identified that evapotranspiration, sediment thickness, and groundwater extraction were the dominant factors in the early stage of subsidence, while recent groundwater management and recharge practices have significantly mitigated the subsidence rate. These findings demonstrate the shifting importance of different subsidence factors over time and provide valuable insights for long-term prevention and control measures.

As the energy system undergoes a growing reliance on renewable energy while the role of conventional thermal power declines, a utility-scale energy storage system of sufficient capacity may help to ensure supply reliability. Pumped Hydro Storage (PHS) technology dominates utility-scale energy storage and, with its unique advantages, is poised to serve as a mature solution for addressing the inherent intermittency and unpredictability of renewable energy. Past research on PHS has given priority to a substantial elevation difference, which has led to an underestimation of its potential. Therefore, this study focuses on mid-head PHS (30–100 m) and explores its technical feasibility in the Great Lakes region, where large natural basins and suitable topography provide favorable conditions for this type of PHS, aligning with the possible future development of lake-based wind power, indicating potential synergies in power integration and infrastructure co-location. This study identifies the distribution of potential open-loop PHS sites along the Great Lakes shoreline within Michigan and demonstrates that their storage potential far exceeds the storage required for carbon reduction goals in the following decades. The economic analysis also demonstrates that the levelized cost of energy (LCOE) for these storage systems, which meet the demand, is only $30–40/MWh, far lower than other utility-scale energy storage technologies. The study also conducts a sensitivity analysis on the technical parameters of site identification, aiming to address various circumstances regarding preferences and conditions, and demonstrates that the storage in each scenario still far exceeds the required amount.

Floating offshore wind turbines (FOWTs) are gaining increasing attention as a promising solution for harnessing wind energy in deep-water regions, where traditional bottom-fixed turbines are not feasible. Among the various floating platform designs, semi-submersible platforms have emerged as a leading candidate due to their balance of stability, adaptability, and cost-effectiveness. This paper presents a detailed comparative analysis of two typical types of semi-submersible platforms: the three-column design and the three-column with central column design. The study employs a coupled aero-hydro-mooring simulation system using OpenFOAM to evaluate the hydrodynamic, aerodynamic, and mooring dynamics of both platform configurations. High-fidelity computational fluid dynamics (CFD) simulations, along with a lumped-mass mooring model and the actuator line model (ALM), are employed to capture the coupled fluid-structure interactions and mooring line dynamics. The results reveal significant differences in platform behavior, highlighting the impact of platform geometry on dynamic stability and mooring line response. The additional central column significantly improves pitch stability, reducing the maximum pitch angle by 38.7 % under combined wind and wave loading, indicating enhanced dynamic stability of the additional central column design. Additionally, an economic assessment is provided to evaluate the material costs, installation, and operational expenses for each platform type. The findings suggest that both configurations offer distinct advantages depending on operational and environmental conditions, contributing to the optimization of FOWT platform selection for future offshore wind farms.

Tropical cyclones (TCs) significantly influence coastal sedimentation, geomorphologic features, and morphodynamic processes through strong winds, heavy rains, and storm surges. These effects are particularly pronounced in the east China coastal ocean. However, the impacts of poleward and landward shifts in TC tracks on sedimentology, specifically sediment transport and erosion-deposition processes, remain insufficiently understood. This study utilizes the Delft3D-FM numerical model integrated with TC best track data and field measurements to investigate sediment transport patterns under historical TC tracks and to quantify erosion responses to poleward and landward track shifts. From the historical sediment transport pattern derived from the typical historical TC track, results reveal that sediment in waters shallower than 30 m is highly sensitive to TC activity, with four distinct zones where net sediment transport is sensitive to the change of typical historical TC tracks. Coastal erosion depth changes due to poleward and landward shifts of typical TC tracks during the peak TC intensity period are quantified as 0.24–1.63 cm°N⁻¹ and 0.05–1.06 cm°E⁻¹, respectively. Under global warming scenarios, these values are projected to increase by 2.45%–8.00% and 4.71%–13.33%, respectively. Identifying the coastal areas more susceptible to TC-induced sediment transport and quantitatively assessing the effects of poleward and landward track shifts are important for understanding local TC variability and supporting research on sedimentology during TCs and the future protection of coastal areas.

Hydropower plays a critical role in global renewable energy production, yet its environmental impacts on aquatic ecosystems remain a concern. This study investigates the biological impacts of Shaft-Driven Variable-Speed Contra-Rotating Propeller Reversible Pump Turbines (SDCRRPTs) on fish populations, using Atlantic salmon (Salmo salar) and European eel (anguilla) as experimental models. These species present critical ecological and conservation traits, making them ideal models for assessing hydropower-induced stressors such as rapid decompression, shear, collision, and turbulence. Through Computational Fluid Dynamics (CFD) simulations and the Biological Performance Assessment (BioPA) tool, two SDCRRPT prototypes were evaluated under varying operating conditions. Results indicate that rapid decompression posed minimal risks, while shear stress was the primary cause of mortality for salmon, and collision effects were moderate but species-dependent. The optimized turbine design (Prototype 1) demonstrated improvements in adult fish passage safety compared to the initial design, particularly for eels, yet persistent vulnerabilities highlight the need for further refinements and protective measures, such as physical, mechanical or sensory behavioral barriers combined with bypass systems, to mitigate unavoidable mortality risks during turbine passage. The findings highlight the potential for species-specific design optimization to balance ecological conservation with sustainable energy production. This work underscores the importance of integrating environmental considerations into hydropower technologies to support the EU's decarbonization goals while safeguarding aquatic biodiversity.

The structural response of masonry walls during flood events is a critical concern for the flood resilience of (Dutch) buildings, as they typically constitute part of the load-bearing structure. This study investigates the out-of-plane behaviour of a full-scale single-wythe fired-clay-brick masonry wall under out-of-plane hydrostatic pressure and debris impact loads. Experimental tests were conducted on a 2.7 × 2.7 m masonry wall subjected to a vertical pre-compression and simultaneously varying water levels and debris impacts at the Flood Proof Holland facility in Delft, the Netherlands. Results demonstrated that the wall remained within the linear-elastic regime up to a water depth of approximately 90 cm when the interior side was dry. Beyond this threshold, crack initiation and stress redistribution occurred, leading to significant deformation. On the basis of calibrated models, failure was predicted at approximately 150 cm water depth for a fully restrained wall. Debris impact tests showed that soft debris, represented by a floating log, caused negligible additional damage, whereas repeated impacts with a steel cube (hard debris) resulted in progressive cracking and local failure, particularly at higher water levels. Numerical models, including analytical, linear-elastic finite element method (FEM), and non-linear FE approaches, were calibrated using the experimental data. While one-way bending models predicted conservative failure thresholds, two-way, non-linear models accurately captured the wall’s deformation and cracking behaviour, demonstrating the importance of lateral boundary constraints in determining wall capacity and stability. The findings emphasise that traditional masonry walls in Dutch buildings can safely withstand water depths up to 90 cm without significant damage. However, higher water levels or hard debris impacts pose substantial risks, highlighting the need for improved flood resilience strategies. Future work should focus on cavity wall systems, leakage effects, and the behaviour of walls with openings.

Floating Offshore Wind Turbines (FOWTs) operate under complex environmental conditions, where unsteady hydrodynamic forces such as vortex-induced vibrations (VIV) can significantly influence structural response. However, conventional modeling approaches often neglect VIV effects, leading to underestimation of platform motion and hydrodynamic loading. This study incorporates a VIV-induced lift force model into the Morison equation framework within OpenFAST to assess its impact on the dynamic behavior of a spar-type FOWT under steady current conditions. Two simulation cases are compared: one assuming a stationary platform and the other allowing for platform motion through relative velocity coupling. Results show that VIV introduces multi-frequency oscillations in both hydrodynamic force and platform sway response, with amplitudes increasing with current speed. These findings focus on the importance of including VIV effects in hydrodynamic models for accurate prediction of FOWT behavior.

The design of coastal and hydraulic structures must account for extreme conditions, such as wave overtopping, and consider variables that may not be relevant under normal circumstances to ensure safety. This research investigates the characteristics of air cavity pressure and cavity water depth beside an overflowed vertical caisson breakwater, focusing on the influence of flow conditions and hydraulic parameters for a slowly varying, surging-type tsunami. A physical model was used to conduct controlled experiments, enabling the study to explore various scenarios, including subcritical and supercritical downstream flows with varying downstream flume outlet heights and different upstream water depths. Dimensionless equations for air cavity pressure and cavity water depth were derived through multivariate regression analysis, providing a systematic approach to analyze their behaviors under different flow conditions. The results show that air cavity pressure is significantly influenced by the presence of air in the cavity, with a transition from fully ventilated to partially or non-ventilated conditions as the upstream water depth increases. Cavity water depth is observed to be deeper in the non-ventilated case, aligning with previous studies. The derived dimensionless equations demonstrate strong correlations, offering valuable tools for predicting air cavity pressure and cavity water depth under various scenarios, contributing to the design and analysis of hydraulic structures. This study provides insights into wave-structure interactions, extreme wave loads, and the dynamic responses of coastal infrastructures under wave-induced conditions. Overall, this research advances our understanding of air cavity pressure and cavity water depth behaviors, providing essential data for optimizing the design, performance, and safety of hydraulic and marine structures in response to complex ocean wave loads.

The July 2021 flood heavily affected many inhabitants, buildings and critical infrastructure throughout Germany, Belgium and the Netherlands. Specifically, the Ahr Valley (Germany) showcased the destructive power associated with these extreme events. Hence, this region was the focus of a field survey, aiming at describing the flood-induced damage to buildings and assessing the possible underlying processes that led to structural failures. The field assessment revealed a close connection between building failures and (1) local flow depths and velocities, (2) building location, (3) distance from the riverbank and (4) construction type. Although it is difficult to identify the exact causes that induced failures, the detailed assessment revealed that damages mainly originated from local scour and hydraulic loads, often unevenly distributed around buildings. Importantly, many buildings were significantly affected by (large) floating debris impacts and damming, both responsible for additional loads, highlighting their importance in flood-resistant building design. Furthermore, data showed that buildings near the riverbanks and in the upstream part of villages were more severely damaged. Altogether, data provide a better understanding of the flood processes that lead to building failures, fostering future research towards the development of safer protection measures and more effective flood risk management strategies.

Background: The share of renewable energy feeding the European grid has been growing over the years, even though the intermittency of some renewable energy sources can induce electric grid instability. Energy storage has proven to be an effective way of reducing grid instability. Various solutions for large-scale energy storage are being researched nowadays. This study focusses on the innovative low-head pumped hydro storage (LH PHS) technology, a large-scale energy storage scheme suitable for shallow seas (5 – 30 m depth). Implementation of renewable energy technologies, such as wind farms in Europe, Asia and North America, has faced public opposition which has delayed or even cancelled the implementation of renewable energy projects. Literature about public perception of projects highlights the importance of involving stakeholders from the early stages of project planning. Considering this, the present study aims to collect stakeholder opinions (via an online survey) to determine what is necessary for a smooth implementation of LH PHS in the North Sea, both from technical and policy points of view. Results: Stakeholders from commercial parties, government authorities and local groups recognized the potential of LH PHS as a means to increase the share of renewable energies within the European power grid. Economics, bureaucratic burden, and structural safety have emerged as primary aspects of concern respecting the implementation of LH PHS. The impression of the respondents is that a low-head pumped hydro station would not have negative effects on their organizations. Furthermore, most of the engineering firms participating in the study communicated that their knowledge and resources could be involved in the construction of such an energy storage facility. Conclusion: As identified stakeholder concerns such as economics and structural safety are currently being researched, effective communication of the findings of this research is paramount to keep stakeholders informed of the ongoing progress. Two-way communication between researchers and stakeholders is recommended to enhance public acceptance of future technologies. Furthermore, is it advisable to undertake an examination of the available energy policies relevant to LH PHS.