Water Velocity Research Articles

Study on the Swimming Behavior of Black Carp (Mylopharyngodon piceus) and Silver Carp (Hypophthalmichthys molitrix) in Early Developmental Stage

Fish need to make different responses to different water flow conditions, as a variety of fish utilize or overcome the water flow while fish are in the water. This study aims to analyze the response of two types of carp (black carp and silver carp) to water flow in different body lengths (2.0–10.0 cm) in early developmental stages in an open channel. By analyzing the water velocity and fish swimming behavior, swimming against the water flow was the most frequent swimming behavior, and the frequencies of this behavior increased with the increased body length of fish. The results demonstrated that the detectable water velocity of two carp species of different body lengths remained in a certain range (0.020–0.060 m/s). Black carp and silver carp can swim against the water flow of 0.295–0.790 m/s and 0.245–0.825 m/s, respectively. The results of this study can provide invaluable data for engineers and biologists to protect fish in the early developmental stage and restore the ecological habitats in the regulated river systems.

Experimental study of hydrodynamic characteristics in three-phase coarse particle fluidized flotation column

Understanding multiphase flow regimes and hydrodynamic characteristics in the three-phase coarse particle fluidized flotation column (TFC) is crucial in mineral processing. This study systematically investigated the influence of gas velocity (Ug) and water velocity (Uw) on the flow regimes in TFC, focusing on the identification and hydrodynamic characteristics of different flow regimes in the freeboard and bulk fluidized bed regions. Three distinct flow regimes (heterogeneous flow, pseudo-homogeneous flow and mono-homogeneous flow) and two transition water velocities (transitions from a heterogeneous flow regime to a pseudo-homogeneous flow (Ut1) and transitions from a pseudo-homogeneous flow to a mono-disperse homogeneous flow regime (Ut2)) were identified in the freeboard region based on the visual observation and bubble characteristic parameter acquisition system (BVW-2) monitoring the variations in the bubble size distribution. Visual observation combined with electrical resistance tomography (ERT) monitoring the solid concentration variations facilitated accurate determination of three flow regimes (fixed bed regime, agitated bed regime, and complete fluidization regime) and two transition points (minimum agitation water velocity (ULma) and minimum fluidization water velocity (ULmf)) in the bulk fluidized bed region. Furthermore, statistical and spectral methods were used to analyze pressure fluctuation signals and characterize fluidization behavior across different flow regimes, including the average pressure fluctuation (ΔP¯), the probability density function (PDF), normalized standard deviation (δ), kurtosis (K), skewness (S), autocorrelation function (ACF), power spectral density (PSD) and average cycle frequency (fc). The results indicated that it is the changes in dominant flow structures within the three-phase fluidized bed, such as variations in bubble behavior and particle movement under different Ug and Uw, that lead to differences in flow characteristics, thereby forming distinct flow regimes.

Green hydrogen, power, and heat generation by polymer electrolyte membrane electrolyzer and fuel cell powered by a hydrokinetic turbine in low-velocity water canals, a 4E assessment

Thousands of kilometers of man-made low-velocity water transfer canals around the world can be used as a source of renewable energy for electricity and green hydrogen production. These canals have not been well investigated as an energy source, according to the literature. In the present paper, three technologies of Hydrokinetic Turbine (HKT), Polymer Electrolyte Membrane Fuel Cell, and Electrolyzer (PEM-FC/EL) are utilized to produce electricity, green hydrogen, and heat using these canals. Thermodynamic, economic, and environmental models of the cycle are presented, coded in the Engineering Equation Solver software, and finally validated with published research and manufacturers’ data. Two scenarios were examined, first HKT, PEMEL, and PEMFC were used for electricity generation (power-to-hydrogen-to-power, P2X2P) and second only HKT and PEMEL were used for green hydrogen production (power-to-hydrogen, P2X). While both scenarios are economical, the P2X scenario has a smaller payback period (less than 2 years) and a higher net present value. Practical correlations are derived to determine the rate of hydrogen production, power generation, and emission reduction as a function of water velocity. The round-trip energy and exergy efficiency of the system is 46.17% and 20.78% and it reduces carbon dioxide by 0.874 tons/year when water velocity is 1.5 m/s.

Water transport through carbon nanotubes with a peanut-shaped cross-section

Carbon nanotubes are typically characterized by a circular cross-section. However, under hydrostatic pressure, their cross-section can deform into a peanut-like shape. In this study, we explore water transport in carbon nanotubes that exhibit the peanut-shaped cross-section. Our findings reveal that the axial separation in the peanut-shaped carbon nanotube significantly impacts water transport. We attribute these effects to changes in water molecule occupancy, average water velocity, and the order parameter of water, all of which are finely influenced by the axial separation. These results enhance our understanding of the water transport mechanisms in carbon nanotubes with peanut-shaped cross-sections.

Prediction of Scour Depth for Diverse Pier Shapes Utilizing Two-Dimensional Hydraulic Engineering Center’s River Analysis System Sediment Model

Examining scouring around bridge piers is crucial for ensuring water-related infrastructure’s long-term safety and stability. Accurate forecasting models are essential for addressing scour, especially in complex water systems where traditional methods fall short. This study investigates the application of the HEC-RAS 2D sedimentation model, which has recently become available for detailed sediment analysis, to evaluate its effectiveness in predicting scoring around various pier shapes and under different water conditions. This study offers a comprehensive assessment of the model’s predictive capabilities by focusing on variables such as water velocity, shear stress, and riverbed changes. Particular attention was paid to the influence of factors like floating debris and different pier geometries on scour predictions. The results demonstrate that while the HEC-RAS 2D model generally provides accurate predictions for simpler pier shapes—achieving up to 85% precision—it shows varied performance for more complex designs and debris-influenced scenarios. Specifically, the model overpredicted scouring depths by approximately 20% for diamond-shaped piers and underpredicted by 15% for square piers in debris conditions. Elliptical piers, in contrast, experienced significantly less erosion, with scour depths up to 30% shallower compared to other shapes. This study highlights the novel application of the HEC-RAS 2D model in this context and underscores its strengths and limitations. Identified issues include difficulties in modeling water flow and debris-induced bottlenecks. This research points to the improved calibration of sediment movement parameters and the development of advanced computational techniques to enhance scour prediction accuracy in complex environments. This work contributes valuable insights for future research and practical applications in civil engineering, especially where traditional scour mitigation methods, such as apron coverings, are not feasible.

Simulation and Experiments on Optimization of Vortex-Induced Vibration Power Generation System Based on Side-by-Side Double Blunt Bodies

In order to improve the utilization efficiency of converting low-flow current energy into electric energy for Reynolds number 10,000 ≤ Re ≤ 40,000, this paper proposes a vortex-induced vibration power generation system based on a side-by-side double blunt body. In this system, the side-by-side double blunt body structure is used in the current energy capture part to enhance the collection of low-flow current energy; the permanent magnet linear motor is used in the electric energy conversion part to improve the efficiency of electric energy conversion; and a laboratory device is constructed for testing. The effects of the blunt body structure parameters and the center spacing ratio on the energy harvesting performance of the system are qualitatively explained by constructing a simulation model. Compared with the single blunt body energy capture structure, the side-by-side double blunt body structure increases the vibration amplitude by 1.04 times and the lift by 1.14 times at the center spacing S/D = 2.4. Meanwhile, energy harvesting can be realized at a lower flow velocity, increasing the vortex-induced vibration’s energy capture range. Finally, the power generation system was experimentally verified in the laboratory, and the results showed that the vibration amplitude of the double blunt body structure was increased by 1.12 times compared to the single blunt body. The maximum output power of the generator is 10.55 W when the water velocity is 0.7 m/s. The energy conversion efficiency of the power generation system can reach a maximum of 52.93%, which is 12.33% higher than that of a single blunt body structure, which proves that the system has a higher power conversion efficiency than that of a conventional single conversion system.

Spatiotemporal variations and driving factors of fine-scale habitat use by the Yangtze finless porpoise population in the Yangtze River.

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is critically endangered and has suffered from extensive habitat loss and fragmentation. Knowledge of its habitat preference could assist the conservation of the species and associated ecosystem. In the present study, spatiotemporal variations and driving factors of habitat use of a Yangtze finless porpoise population were studied in a 30-km section of the Yangtze mainstream. Seasonal variation in porpoise occurrences was observed based on visual surveys conducted from 2022 to 2023, with five surveys during the dry season and seven surveys during the wet season. Biological and environmental factors were synchronously sampled in both seasons. The maximum entropy model (MaxEnt) was applied to get the effects of biological and environmental variables on porpoise habitat preference. Within the study area, high-suitability habitats of the finless porpoises accounted for 19.0% and 15.4% of the area during the dry and wet seasons, respectively. The high-suitability habitat shifted from the mainstream in the dry season to the sandbar head and tributary area in the wet season. In the dry season, variables influencing the distribution were phytoplankton biomass, water velocity, and zooplankton biomass, which contributed 97.05% variation in the MaxEnt modeling. In the wet season, water depth, surface water temperature, and zooplankton biomass accounted for 97.69% variation of the distribution. Above results highlight that food availability plays an important role in porpoises distribution regardless of seasons, particularly in the dry season. This is because plankton is the primary food source for filter-feeding and omnivorous fish, especially those in the upper-middle layer which are frequently preyed on by finless porpoises. Suitable areas for finless porpoises, particularly those with high suitability, differed significantly across seasons at a fine-scale in the Yangtze mainstream. Seasonal variations in habitat were driven by different factors. But food availability plays an important role in porpoises distribution regardless of seasons, particularly in the dry season. These results suggest prioritizing conservation of the finless porpoise in the dry season when fish resources are relatively scarce. Measures including monitoring and evaluating prey resources should be considered. More attention should also be paid on management of shipping in the dry season given that the high-suitability habitat of the finless porpoises shifts to the mainstream.

Modeling the Impact of Wind Drag Coefficient on Wind-Driven Currents in Lake Taihu, China

The wind drag coefficient, Cd, has a great influence on the numerical results obtained from shallow lakes. To analyze the modeling impacts of Cd on wind-driven currents, a series of numerical simulations of Lake Taihu were conducted at three grid resolutions (800 m × 800 m, 400 m × 400 m, and 100 m × 100 m) using the empirical formulae of Flather (F76), Large and Pond (LP81), Large and Yeager (LY04), Andreas (A12), and Gao (G20). The G20 formula produced the optimum results of all the formulae for both the water level and velocity simulations; however, the grid resolution was found to have a significant influence on simulation in G20 cases. Thus, the G20 formula is only recommended when using a high-resolution grid to meet the accuracy requirements of analyzing wind-driven currents in the numerical modeling of Lake Taihu. A combination of the A12 formula and a coarse grid is preferred when taking computational efficiency into consideration.

Study of the influence of rheological parameters on the behavior of a submarine debris flow

Submarine debris flows are events that occur with great frequency on a geological scale and can cause major damage to offshore structures or even loss of human life. Understanding the mechanisms involved in the development of a debris flow requires not only knowledge of soil mechanics, but also knowledge of fluid mechanics, since the incorporation of water during the flow causes changes in shear strength. Unlike soils, the shear strength of fluids is represented by mathematical models called rheological models. The objective of this paper is to propose a new rheological model capable of representing the changes caused by water entrainment into a submarine debris flow, by correlating it with the Liquidity Index of the soil. A rheological analysis of marine clay samples from the pre-salt layer has made it possible to represent the variation in strength due to water content. The influence of water content and velocity on flow behavior has also been studied through the analysis of centrifuge tests performed in a previous study.

Synergistic effects of temporal variations in flow and chemistry on colloid retention and remobilization in saturated porous media

Rapid infiltration due to rainfall events, groundwater pumping, and artificial recharge of groundwater result in temporal variations in both flow and chemistry in the subsurface and may lead to remobilization of retained colloids, thereby re-contaminating the groundwater resources. Many researchers have studied the effects of temporal variations in water velocity and in water chemistry separately. These variations, however, almost always occur simultaneously. To the best knowledge of the authors, there are no studies reported in the literature where the effect of simultaneous temporal variations in flow velocity and ionic strength on colloid release is investigated. One cannot assume that those effects can be simply superimposed. In fact, in this study, we show that these effects are not simply additive. We have performed eight sets of saturated column experiments on the effects of temporal variations in flow velocity alone and simultaneous temporal variations in flow velocity and ionic strength on retention and remobilization of colloids. Temporal increases in average water velocity caused an instantaneous spike release of colloids in the measured breakthrough curve, with the time to peak coinciding with the instant of velocity increase. Further, the effect of temporal variations in average water velocity on remobilization of deposited colloids is ionic-strength dependent. The simultaneous temporal increases in flow and decreases in ionic strength caused a spike release of colloids followed by long tails. The release curve for every step-change in velocity and ionic strength was unimodal for deposition ionic strengths of 100 and 10 mM, with the peak coinciding with the instant of arrival of ionic strength front at the column outlet. However, the release curve was bimodal for deposition ionic strengths of 50 and 25 mM. There, the first instantaneous spike coincided with the instant of increase in flow velocity, and the second delayed one coincided with the passage of the ionic strength front. Temporal variations in both flow and ionic strength released more colloids in the effluent than when only ionic-strength or only flow velocity was varied. This is due to the combined effects of greater hydrodynamic torque exerted on attached particles together with smaller adhesive torque.

Spawning Redd Habitat Use and Selection by Invasive Brown Trout (Salmo trutta) Along a Longitudinal Gradient in a Headwater Stream

ABSTRACTAs stream habitats change from upstream to downstream, choice of spawning redd sites by brown trout may shift as habitat availability changes. In a previous study, we examined the importance of overhead cover or shade in redd site selection. Here, we examined spawning site habitat use and selection by brown trout by assessing physical characteristics at redd sites in a 4.8‐km reach of Garvin Brook (southeastern Minnesota, USA) during each of five spawning seasons, 2016–2020. We measured redd dimensions, water depths, and current velocities, and compared these among four separate sections (900–1900 m in length) of the stream. We also assessed available habitats within each section to examine possible selection of habitats by spawning trout, plus quantified the size distribution of gravel substrate at redd sites within two stream sections. Habitat availability varied dramatically among stream sections. After analyzing 1844 redds from the five spawning seasons, brown trout displayed strong selection for water depths between 10 and 29 cm and current velocities between 10 and 49 cm/s. Preferred/selected water depths and current velocities increased by 7 cm and 10 cm/s, respectively, between upstream and downstream sections. All redds were located in gravel/cobble substrates, with variations in size distributions of gravels not correlated to redd dimensions or any measured habitat variable. Spawning site preferences of brown trout can change along a stream reach of moderate length, likely in relation to changing availability of various combinations of water depth, velocity, substrate, available cover, and trout abundance.

Simulation of the Full‐Process Dynamics of Floating Vehicles Driven by Flash Floods

AbstractFlash flooding has become more prominent under climate change, threatening people's life and property. Post‐event investigations of recent events emphasize the role of floating debris, such as vehicles, in exacerbating damage. Few modeling methods and tools have been developed to simulate the full‐process dynamics of floating debris driven by large‐scale flood waves in real world. In this work, a fully coupled model is developed for simulating the full‐process interactive movements of vehicles driven by flash flood hydrodynamics, from entrainment, transport to deposition. The proposed coupled modeling system consists of a finite volume shock‐capturing hydrodynamic model solving the 2D shallow water equations and a 3D discrete element method (DEM) model. The proposed two‐way coupling approach estimates the hydrostatic and hydrodynamic forces acting on solid objects using the water depth and velocity predicted by the hydrodynamic model; the resulting counter forces on the fluid flow are then considered by adding extra source terms in the hydrodynamic model. A multi‐sphere method is further embedded in the DEM model to better represent vehicle shapes. New calculation modules are further implemented to represent the vehicle entrainment, contact and stopping motions. The coupled model is applied to reproduce a flash flood event hit Boscastle in the UK in 2004. Over 100 vehicles were moved and carried downstream by the highly transient flood flow. The model well predicts the hydrodynamics, interactive transport process and the final locations of vehicles. The proposed coupled model provides a new tool for simulating large‐scale flash flooding processes, including debris dynamics.

Design of experimental section of a water tunnel for simulation of heat dissipation condition of seawater-activated battery

Abstract A water tunnel is a crucial experimental apparatus in hydrodynamic research, as the traditional water tunnel has drawbacks such as a small cross-sectional area of the test section and higher costs, which makes it difficult to meet the requirements of a water tunnel for simulating the heat dissipation conditions of the seawater-activated battery. This paper proposes a water tunnel specifically designed for simulating the heat dissipation conditions of seawater-activated batteries, and the water tunnel consists of an external cooling water circulation system and an internal electrolyte circulation system. The experimental section’s design determines the water tunnel’s size and key technical indexes. The temperature distribution contour maps of the experimental section were obtained using Ansys Fluent software simulation. The cooling effect was analyzed, and a cooling water flow rate of 10 m/s was selected. Pressure and velocity contour maps were obtained by simulating the experimental section of the water tunnel. The results show that when the cooling water velocity is 10 m/s, the pressure drop of the experimental section is approximately 1.76 atmospheres. The flow field is uniform and stable, and the heat dissipation power can reach 45.5 kW, meeting the technical requirements.

Design and Fabrication of a Wind and Hydropower Turbines

Abstract Nowadays, there is an increase in the use of fossil fuels in energy production and the increase in the pollutants of its combustion. Governments have reinforced over the past few years to reduce the dependence on fossil fuels and reduce the pollution emitted by traditional methods of producing energy. By using hydropower and wind, energy can move away from the use of fossil fuels and negative effects. Therefore, hydropower and wind energy have been created that depend on renewable and environmentally safe energy. This work focused on building a device that integrates hydropower and wind energy together. This project focused on designing the combined between the hydropower and wind. Therefore, a model of a wind and hydropower turbine has been designed and fabricated. The idea of the paper is to develop a combined system between the wind and hydropower to generate the electricity. The system consists of a wind turbine and hydropower turbine. The wind one is on the top facing the winds directions and the hydropower part is inside the water to convert the water velocity to electricity. The wind turbine and hydropower turbine were connected. The idea behind that to ensure the wind turbine will not be stopped in working while there is no wind.

Long-Term Changes in Deep Ocean Currents between Ulleung Island and Dok Island in the East Sea from 1996 to 2023

This study presents a comprehensive analysis of long-term deep ocean currents between Ulleung Island and Dok Island in the East Sea, based on data observed from the East Sea Current Measurement 1 (EC1) mooring station spanning from 1996 to 2023. The deep current at the Ulleung Interplain Gap, a trough situated between Ulleung Island and Dok Island, originates from the Japan Basin, a region where deep water formation occurs within the East Sea. The southward flow and velocity of this deep water are reflective of both regional and global climate dynamics. Understanding these dynamics is crucial for assessing environmental impact, both locally in Korea and globally. Significant trends and anomalies were identified in the zonal and meridional velocities within the 1,800 and 2,500-meter depth range. Data from 2012 to 2014 required corrections due to unit inconsistencies, which, after adjustment, revealed a deceleration of the southward bottom current, with speeds decreasing from 1.49 cm s<sup>-1</sup> in November 1996 to 1.14 cm s<sup>-1</sup> in April 2023. These changes may be linked to global climate variations and bottom water formation in the Japan Basin, influencing regional circulation patterns. The findings highlight the importance of sustained ocean monitoring and enhanced data management to ensure the accuracy and utility of long-term oceanographic datasets.

Effect of Fine-Pore Aeration Tube Layout on Dissolved Oxygen Distribution and Aeration Performance in Large-Scale Pond

Dissolved oxygen (DO) is a crucial water quality characteristic in the cultivation of vannamei shrimp. Increasing the DO concentration in shrimp ponds can be carried out using the aeration method with a tool called an aerator. In this study, types of fine-pore aeration tubes are chosen. This aerator offers multiple benefits, such as superior aeration efficiency, effortless installation, and minimal clogging. In practice, fine-pore aeration tubes can be arranged according to needs, so the layout used can influence the resulting aeration performance. This research uses the computational fluid dynamics (CFD) method to analyze DO distribution, water circulation, and aeration performance (KLa20, SOTR, and SOTE) produced in various aerator layouts, namely straight-type, ring-type, and square-type, in a vannamei shrimp pond. The results show that the straight-type layout has the best DO distribution because it is spread throughout the pond area. The square-type layout has the best water circulation because it has the largest area with water velocities of less than 5 cm/s. The optimal aeration performance was achieved with the straight-type layout, which demonstrated a KLa20 value of 3.16 h−1, SOTR value of 19.20 kg/h, and SOTE of 29.30%.

Bioecology of blackflies (Diptera: Simuliidae) of the water basin of the Huebra River (Western Spain)

The objectives of this study were to analyse the diversity and geographical distribution of the blackfly species from the Huebra River basin located in Salamanca province, Western Spain. This research significantly contributes to expanding our knowledge of the Simuliidae family. The study not only increases and ameliorates faunal and bioecological data, but also enhances the understanding of blackfly species across the Spanish national territory. The identification of 23 species has led to the addition of six new records to the simuliid fauna of the region: Simulium (Nevermannia) armoricanum Doby & David, 1961; Simulium (Nevermannia) carthusiense Grenier & Dorier, 1959; Simulium (Nevermannia) naturale Davies, 1966; Simulium (Nevermannia) vernum Macquart, 1826; Simulium (Simulium) bezzii (Corti, 1914) and Urosimulium faurei (Bernard, Grenier & Bailly-Choumara, 1972), expanding the previously recorded 19 species to 25. This study also provides valuable insights into the biology and geographical distribution of these species. It sheds light on the ranges of altitude, water velocity, temperature and the depth of watercourses conducive to preimaginal development. Additionally, it offers new information on the abundance of larvae and pupae, revealing the diverse ecological gradients that influence their occurrence and distribution patterns. The results indicate that the diversity of blackfly species varies according to factors such as altitude, water velocity, turbidity, and water temperature.

Research on the technical improvement of the turbine runner of a power station based on improving stability

AbstractIn view of problems such as the narrow efficiency area, large hydraulic vibration area, pressure pulsation, and serious sediment wear of turbines at the Futang hydropower station, the technical transformation of turbine runners was carried out by modifying the blade shape and increasing the blade thickness, and a combination of numerical simulations based on shear stress transport k–ω turbulence model and tests was adopted to improve the operational stability of power station units. Calculation and testing demonstrate an enlargement of the high‐efficiency zone. Specifically, the optimal efficiency of the runner increases by 0.37%, while the rated efficiency rises by 0.19%. Significant reductions are observed in pressure pulsation within the draft tube and vaneless area decrease of approximately 50%. There is a high‐frequency pressure pulsation in the vaneless zone and the runner under low‐load conditions, and the influence of dynamic and static interference gradually weakens with the increase of opening. The draft tube is prone to eccentric vortex bands under partial working conditions, which causes the unit to be affected by low‐frequency pulsation. This optimization also leads to a notable decrease in runner blade wear, with the maximum sand and water velocity reduced from 45 to 40 m/s, resulting in a 30% reduction in sand wear. Moreover, there is a substantial enhancement in the runner's stiffness, with the thickness of the blade near the high stress area of the upper crown and lower ring increasing by over 50%, and the weight of each individual blade increasing by more than 50%. These research findings validate that modifying the runner blade effectively improves flow patterns, reduces eddy current generation, minimizes pressure pulsation, widens the high‐efficiency zone, decreases wear, and enhances the operational stability of the unit. The technical transformation method and research results of this study have important guiding significance for similar technical transformation of other power stations

Reduced Streamflow From Water Diversion Alters Stream Ecology and Fish Behavior

ABSTRACTUnderstanding invertebrate and fish responses to altered streamflows is important for water management that balances ecological function and societal needs. We studied the impacts of a significant water diversion on a stream food web, including benthic biofilms, benthic macroinvertebrates (BMI), and drifting macroinvertebrates. In the dry season, drift flux (number of aquatic individuals or biomass/s) and drift concentration (individual/m3) were lower below the diversion than above. Drift concentration (biomass/m3) was slightly higher below the diversion, due to the presence of large Trichopterans. All measures of drift dropped to nearly zero at the end of the dry season below the diversion, when streamflows were reduced by > 90% below the diversion relative to above, representing a significant loss of food resources for trout. Simultaneously, native Rainbow Trout (Oncorhynchus mykiss) switched from drift to benthic foraging 1 month earlier below the diversion as drift and water velocities declined. The ecology of the benthos was not as impacted by the diversion: BMI densities were higher below the diversion, while benthic biofilm densities were similar at the two sites. The taxonomic composition of BMI was also similar between the sites, but fewer Ephemeroptera entered the drift below the diversion. Overall, the late season decrease in drift below the diversion despite the similar or higher benthic production suggests that streamflows influence food availability for trout even in the absence of benthic responses. Reduced streamflows, due to water diversions as studied here, or due to climate change, will likely reduce food resources and growth opportunities for fishes.

Tsunami propagation and flooding maps: An application for the Island of Lampedusa, Sicily Channel, Italy

AbstractThe Mediterranean coastlines are densely populated zones which host key socio‐economic and commercial activities. For this reason, coastal areas are vulnerable sites in case of natural disasters as tsunamis that can strike coasts causing widespread damage to the population and facilities. For these reasons, several studies were performed over the last decade to study the impact of tsunami waves on the coasts. This research assessed the inundation risk due to a tsunami wave which can hit the southeastern coast of Lampedusa Island. The coastal low‐lying geomorphological setting of the southeastern part of the island led to significant socio‐economic growth, but Lampedusa falls within the Mediterranean Sea, a high‐tsunamigenic area, therefore, the need to investigate tsunami propagation and coastal flooding of this sensitive site emerged. For this scope, a calculation chain model was implemented incorporating three steps: the DELFT‐3D software for earthquake effects modelling, MIKE 21 Flow Model FM for nearshore propagation and HEC‐RAS for onshore tsunami inundation modelling. The simulations illustrate the impact of three tsunami scenarios with different magnitudes (Mw 8.5, 7.5, 6.5) generated by hypothetical earthquakes in the Hellenic Arc. In the Mw 8.5 magnitude scenario, significant flooding occurs in the harbour region, with maximum water depths reaching approximately 3.5 m. The maximum water velocity in this scenario reaches about 15 m/s in the eastern portion, adjacent to cliffs impacted by the tsunami wave. In contrast, the Mw 7.5 magnitude scenario demonstrates reduced flooded areas, with the cliffs containing the waves and preventing further flooding. Water depths and velocities in the Mw 7.5 scenario remain minimal. Changes in both propagation and flooding are not significant between scenarios Mw 7.5 and Mw 6.5. This methodology can be employed for more accurate tsunami wave simulations not only in the Mediterranean region but also in various case studies.