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Dalrymple, Robert A., Jamie H. MacMahan, Ad J. H. M. Reniers, and Varjola Nelko. "Rip Currents." Annual Review of Fluid Mechanics 43, no. 1 (2011): 551–81. http://dx.doi.org/10.1146/annurev-fluid-122109-160733.
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Choi, Junwoo, Sung-Bum Yoon, Jimin Ko, and Tae-Soon Kang. "PERFORMANCES OF THE RIP CURRENT WARNING SYSTEM AT THE HAEUNDAE COAST OF SOUTH KOREA." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 20. http://dx.doi.org/10.9753/icce.v36.currents.20.
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Haeundae is one of the most beautiful beaches in Korea, and is also notorious for frequent and strong rip currents. Every recent year in this beach, hundreds of swimmers rescued from rip currents have been reported. The large-scale Haeundae rip current is known to be a kind of transient rip currents which is hardly predicted. The successive ends of wave-crest pattern (i.e., honeycomb wave-crest pattern(Dalrymple et al., 2011)), which generate rip current, are mainly formed by two-directional wave trains due to the refraction of incident swells over submerged shoals and ridges of the Haeundae coast. Many people are caught by the rip current in the relatively calm sea and weather conditions. The incident waves generating rip currents are nearly monochromatic with the wave period of 7-13 seconds. These swells are supposed to be generated by distant typhoons formed in the Philippine Sea. Some of them might propagate with dispersion and dissipation during the travel toward the south coast of the Korean Peninsula, especially to the Haeundae coast. In order to protect the swimmers from the rip current accidents, Choi et al. (2014) proposed a method for a rip current warning system, and Korea Hydrographic and Oceanographic Administration (KHOA) has established and operated the rip current warning system to the Haeundae beach. The rip current warning system estimates the rip current risk level based on the real-time incident wave conditions measured near the beach and the database pre-calculated by a numerical model according to various wave and tide conditions and the topography of the Haeundae coast. The Boussinesq wave model, FUNWAVE (Wei et al., 1999; Choi et al., 2015) was utilized for resolving the ends of the wave crests. This study showed the performance of the forecast and warning system of the rip current at the Haeundae coast of South Korea.
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Winter, Gundula, Ap Van Dongeren, Matthieu De Schipper, and Jaap Van Thiel de Vries. "A FIELD AND NUMERICAL STUDY INTO RIP CURRENTS IN WIND-SEA DOMINATED ENVIRONMENTS." Coastal Engineering Proceedings 1, no. 33 (2012): 36. http://dx.doi.org/10.9753/icce.v33.currents.36.
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Rip currents are wave-induced and off-shore directed flows which occur frequently in the surf zone and can pose a serious threat to swimmers. While the behaviour of rip currents has been studied in swell-dominated environments, less is known about their characteristics in wind-sea dominated environments. This study aims to improve the knowledge on rip currents in these environments such as the Dutch coast. In a field campaign at Egmond aan Zee (The Netherlands), Lagrangian velocities in the surf zone were measured with drifter floats. An extensive dataset of rip current measurements was collected from which parameters that initiate rip currents and affect their mean flow properties were identified. Numerical simulations with XBeach aided to understand and confirm the observations made in the field. A reduction of the hydrodynamic parameters along with simplification of the bathymetry in the model allowed for identification of the governing rip current parameters, which can be the basis for a warning system.
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Zhu, Daoheng, Zhiqiang Li, Pengpeng Hu, Bingfu Wang, Qianxin Su, and Gaocong Li. "Preliminary Investigation and Analysis of Beachgoers’ Awareness of Rip Currents in South China." International Journal of Environmental Research and Public Health 20, no. 5 (2023): 4471. http://dx.doi.org/10.3390/ijerph20054471.
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Among many coastal hazards, rip currents have gradually become one of the most noticeable hazards. Studies have demonstrated that most drowning accidents at beaches around the world are related to rip currents. In this study, online and field questionnaires were combined for the first time to reveal beachgoers’ awareness of rip currents in China from four aspects: demographic characteristics, swimming ability, information about visiting beaches, and knowledge about rip currents. One educational strategy was introduced to the field survey. The results suggest that (i) the proportion of online and field respondents who have heard of “rip currents” and seen warning signs of rip currents is extremely small. This reflects that beachgoers lack awareness of rip current hazards. Thus, China needs to strengthen the safety education of rip current knowledge. (ii) The level of awareness of rip currents can significantly affect the community’s ability to identify the location of rip currents and their choice of escape direction. (iii) In the field survey, we implemented an educational strategy as an intervention for respondents, and the accuracy of identifying rip currents and choosing the correct escape route improved by 34% and 46.7%, respectively. This implies that the intervention of educational strategy can significantly deepen beachgoers’ awareness of rip currents. It is recommended that more educational strategies about rip current knowledge be implemented on Chinese beaches in the future.
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Pitman, Sebastian J., Katie Thompson, Deirdre E. Hart, et al. "Beachgoers' ability to identify rip currents at a beach in situ." Natural Hazards and Earth System Sciences 21, no. 1 (2021): 115–28. http://dx.doi.org/10.5194/nhess-21-115-2021.
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Abstract. Rip currents (“rips”) are the leading cause of drowning on surf beaches worldwide. A major contributing factor is that many beachgoers are unable to identify rip currents. Previous research has attempted to quantify beachgoers' rip identification ability using photographs of rip currents without identifying whether this usefully translates into an ability to identify a rip current in situ at the beach. This study is the first to compare beachgoers ability to identify rip currents in photographs and in situ at a beach in New Zealand (Muriwai Beach) where a channel rip current was present. Only 22 % of respondents were able to identify the in situ rip current. The highest rates of success were for males (33 %), New Zealand residents (25 %), and local beach users (29 %). Of all respondents who were successful at identifying the rip current in situ, 62 % were active surfers/bodyboarders, and 28 % were active beach swimmers. Of the respondents who were able to identify a rip current in two photographs, only 34 % were able to translate this into a successful in situ rip identification, which suggests that the ability to identify rip currents by beachgoers is worse than reported by previous studies involving photographs. This study highlights the difficulty of successfully identifying a rip current in reality and that photographs are not necessarily a useful means of teaching individuals to identify rip currents. It advocates for the use of more immersive and realistic education strategies, such as the use of virtual reality headsets showing moving imagery (videos) of rip currents in order to improve rip identification ability.
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Choi, Junwoo, Min Roh, and Hyung-sik Hwang. "LABORATORY MODEL TEST OF TRANSIENT RIP CURRENTS DUE TO PSEUDO HONEYCOMB PATTERN WAVES." Coastal Engineering Proceedings, no. 36 (December 30, 2018): 19. http://dx.doi.org/10.9753/icce.v36.currents.19.
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The Haeundae coast of South Korea is famous for its beautiful beach, but the rip current, from which the beach-guards rescue more than 100 people every summer at the beach, is now a notorious phenomenon. The large-scale Haeundae rip current is known to be a transient rip current caused by multi-directional wave trains rather than the topography-induced rip current, for example, due to a gap of sandbar. In other words, the rip current seems develop along the cross-shore nodal line area in the honeycomb wave-crest pattern (Dalrymple et al., 2011) which are generated in a shallow water when two wave trains propagate with slightly different wave directions (i.e., interference pattern). The wave pattern is formed by the refraction of incident swells over submerged shoals and ridges of the Haeundae coast. The Haeundae rip current is an example explained by the vortex generation due to the ends of wave crests in Peregrine(1998), which is known of the basic generation mechanism of rip currents(Johnson and Pattiaratchi, 2006; Clark et al., 2012; Feddersen, 2014). To understand the generation mechanism and verify the numerical model results of the Haeundae rip current, the laboratory experiment was planned. This study showed the preliminary laboratory observations which include the pseudo honeycomb pattern of incident waves and its resultant rip current.
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Marshall, David P., Bendix Vogel, and Xiaoming Zhai. "Rossby rip currents." Geophysical Research Letters 40, no. 16 (2013): 4333–37. http://dx.doi.org/10.1002/grl.50842.
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Ngo Nam Thinh and Nguyen Thi Bay. "Development of a Two-Dimensional Hydrodynamic Model to Simulate Rip Currents in the Bai Dai-Cam Ranh Coast, Vietnam." Journal of Environmental & Earth Sciences 7, no. 4 (2025): 203–16. https://doi.org/10.30564/jees.v7i4.8574.
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Rip currents are a significant threat to swimmers worldwide, responsible for numerous drowning incidents each year. In Vietnam, Bai Dai Beach in Cam Ranh Bay, Khanh Hoa Province, has experienced an increase in drowning events due to rip currents in recent years. To address this issue, a comprehensive study was conducted based on developing a depth-averaged 2D hydrodynamic model to simulate rip currents in the Bai Dai-Cam Ranh coast. The HYDIST-2D numerical model was applied to simulate the rip current evolution in space and time for the study area. The results showed that the HYDIST-2D numerical model can accurately predict the location, magnitude, and microstructure of rip currents, including rip current speed, width, and length. The simulation results revealed that the rip current speed is greater during the low tide phase, with an average speed of 0.5 m s–1, while during high tide, the rip current speed is lower, around 0.1–0.8 m s–1. The width and length of the rip current also vary with the tide phase, with a wider and longer rip current observed during the low tide phase. The results also showed that the rip current speed and microstructure are influenced by the wave features, tide current, and bathymetry of the study area. The present study provides valuable insights into the dynamics of rip currents in the Bai Dai-Cam Ranh coast. The findings can be used to support the management of bathing activities and provide early warnings for potential risks associated with rip currents.
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Ji, Xinran, Chuanle Xu, Zhiyuan Ren, Sheng Yan, Daoru Wang, and Zongbing Yu. "Study on the Formation Characteristics and Disaster Mitigation Mechanisms of Rip Currents on Arc-Shaped Beach." Journal of Marine Science and Engineering 11, no. 12 (2023): 2381. http://dx.doi.org/10.3390/jmse11122381.
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Rip currents are fast offshore currents generated during the breaking process of waves propagating nearshore, posing a potential life safety threat to coastal bathers. This study utilizes a Boussinesq phase-resolving model to investigate the formation mechanism of rip currents at Dadonghai Beach, based on its actual topography, and explores the characteristics of rip current formation under various wave conditions, with an emphasis on analyzing vortices, the mean water level and the spatial distribution of average velocity. The results indicate that rip current formation is significantly influenced by wave height and period. The increase in wave height and period results in more intense rip currents and higher water level fluctuations on arc-shaped beaches and on both sides of the bay, leading to complex vortex distributions. An increase in the angle of wave incidence hinders rip current formation in arc-shaped beach areas but is favorable to the generation of deflection rips on both sides of the bay. Furthermore, an increase in bottom friction inhibits rip current formation. When the water depth decreases in the channels, rip currents transition into longshore currents. The findings of this research offer valuable scientific insights into the formation mechanisms of rip currents and contribute to their prediction and prevention.
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Ishikawa, Toshinori, Ryo Shimada, and Tsutomu Komine. "RIP CURRENT DETECTION IN AN OPEN AREA AND ALONG JETTY USING AI." Coastal Engineering Proceedings, no. 37 (September 1, 2023): 7. http://dx.doi.org/10.9753/icce.v37.papers.7.
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The occurrence of drowning accidents on beaches is mainly caused by rip currents. In this study, we created a single AI model that can detect two types of rip currents with different characteristics: a flash rip current that occurs intermittently in open areas, and a fixed rip current that occurs along jetty. As a result of creating the AI model under various conditions, it was possible to detect the rip currents at each location with high accuracy at the stage of making the AI model. At the final point of the model’s evolution, the accuracy, the precision and the recall rates of the rip current detection were 87 percent, 48 percent and 100 percent, respectively. As a result of actually operating this AI model on the study beach, the single AI model could detect rip currents along the jetty and in the open area. However, it was confirmed that the AI model could not detect all rip currents which were continuously generated along the jetty.
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Drozdzewski, D., W. Shaw, D. Dominey-Howes, et al. "Surveying rip current survivors: preliminary insights into the experiences of being caught in rip currents." Natural Hazards and Earth System Sciences 12, no. 4 (2012): 1201–11. http://dx.doi.org/10.5194/nhess-12-1201-2012.
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Abstract. This paper begins a process of addressing a significant gap in knowledge about people's responses to being caught in rip currents. While rip currents are the primary hazard facing recreational ocean swimmers in Australia, debate exists about the best advice to give swimmers caught in rip currents. Such surf rescue advice – on what to do and how to respond when caught in a rip – relies on empirical evidence. However, at present, knowledge about swimmers reactions and responses to rip currents is limited. This gap is a considerable barrier to providing effective advice to beach goers and to understanding how this advice is utilised (or not) when actually caught in the rip current. This paper reports the findings of a pilot study that focussed on garnering a better understanding of swimmers' experiences when caught in rip currents. A large scale questionnaire survey instrument generated data about rip current survivors' demographics, knowledge of beach safety and their reactions and responses when caught in a rip current. A mix of online and paper surveys produced a total of 671 completed surveys. Respondents were predominantly an informed group in terms of rip current knowledge, beach experience and had a high self-rated swimming ability. Preliminary insights from the survey show that most respondents recalled a "swim across the rip/parallel to the beach" message when caught in the rip and most escaped unassisted by acting on this message. However, while nearly a quarter of respondents recalled a message of "not to panic", short answer responses revealed that the onset of panic inhibited some respondents from recalling or enacting any other type of beach safety message when caught in the rip current. Results also showed that despite the research sample being younger, competent and frequent ocean swimmers, they were more likely to swim at unpatrolled beaches and outside of the red and yellow safety flags. Moreover, they were still caught in a rip current and they panicked. The findings of this study have significant implications for a range of demographic groups of differing beach safety knowledge and swimming ability who may be caught in rip currents behave, we know very little about how beach goers may respond to being caught in them.
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Mackellar, Katherine, Robert Brander, and Wendy Shaw. "YouTube Videos and the Rip Current Hazard: Swimming in a Sea of (Mis)information." International Journal of Aquatic Research and Education 9, no. 3 (2015): 348–63. http://dx.doi.org/10.1123/ijare2015-0030.
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Rip currents are strong, narrow, offshore flows found on many global beaches and contribute to hundreds of drownings and tens of thousands of rescues each year. Yet despite long-standing educational efforts, public understanding of rip currents is poor. YouTube represents a new visual-based social media platform with the potential to educate a large and global audience about the rip current hazard. This study analyzed the content of 256 rip current–related YouTube videos with over 5 million total views as of March 2, 2015 finding that the accuracy of informa- tion disseminated about rip currents on YouTube is mixed and of varying quality. Existing videos are good at emphasizing correct rip current terminology, visual imagery, and a range of escape strategies, but greater emphasis in future videos must be placed on rip current avoidance, particularly through promoting the need to swim near lifeguards and how to spot rip currents.
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Ruju, Andrea, Pablo Higuera, Javier L. Lara, Inigo J. Losada, and Giovanni Coco. "RIP CURRENTS ON A BARRED BEACH." Coastal Engineering Proceedings 1, no. 33 (2012): 38. http://dx.doi.org/10.9753/icce.v33.currents.38.
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This work presents the numerical study of rip current circulation on a barred beach. The numerical simulations have been carried out with the IH-FOAM model which is based on the three dimensional Reynolds Averaged Navier-Stokes equations. The new boundary conditions implemented in IH-FOAM have been used, including three dimensional wave generation as well as active wave absorption at the boundary. Applying the specific wave generation boundary conditions, the model is validated to simulate rip circulation on a barred beach. Moreover, this study addresses the identification of the forcing mechanisms and the three dimensional structure of the mean flow.
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Wang, Yan, Zhili Zou, Zhongbo Liu, and Meixia Song. "Vertical Distribution of Rip Currents Generated by Intersecting Waves in a Sandbar–Groin Systems." Journal of Marine Science and Engineering 12, no. 6 (2024): 911. http://dx.doi.org/10.3390/jmse12060911.
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To analyze the impacts of groins, sandbars, and channels on the three-dimensional features of rip currents, we conducted experimental investigations on the vertical distribution of rip currents under intersecting waves along barred beaches with channels. This study employed ADV flow velocity measurements at two distinct locations: within channel and on a sandbar. The results indicate that in nodal sections within channel and on a sandbar, the rip head region manifests surface flow characteristics, characterized by high velocities near water surface. In a rip neck location, the vertical distribution of rip currents on a sandbar exhibits greater variability, whereas within channel, the distribution is more homogeneous. The vertical distribution of rip currents in nodal sections within channel aligns with the logarithmic distribution law. The vertical distributions of the alongshore velocity of rip currents display a consistent pattern of higher at the top and lower at the bottom. However, this pattern varies slightly depending on the wave period. The presence of groins influences the fluctuation characteristics of the alongshore velocity of rip currents by regulating the nearshore circulation system. This results in the alongshore velocity of rip currents in channel pointing towards the groin. In contrast, the alongshore velocity of rip currents on sandbar, situated farther away from groin, exerts a weaker effect on the alongshore velocity of a rip current.
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HALLER, MERRICK C., and R. A. DALRYMPLE. "Rip current instabilities." Journal of Fluid Mechanics 433 (April 25, 2001): 161–92. http://dx.doi.org/10.1017/s0022112000003414.
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A laboratory experiment involving rip currents generated on a barred beach with periodic rip channels indicates that rip currents contain energetic low-frequency oscillations in the presence of steady wave forcing. An analytic model for the time-averaged flow in a rip current is presented and its linear stability characteristics are investigated to evaluate whether the rip current oscillations can be explained by a jet instability mechanism. The instability model considers spatially growing disturbances in an offshore directed, shallow water jet. The effects of variable cross-shore bathymetry, non-parallel flow, turbulent mixing, and bottom friction are included in the model. Model results show that rip currents are highly unstable and the linear stability model can predict the scales of the observed unsteady motions.
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Barlas, Baris, and Serdar Beji. "RIP CURRENT FATALITIES ON THE BLACK SEA BEACHES OF ISTANBUL AND EFFECTS OF WINDS." Coastal Engineering Proceedings, no. 35 (June 23, 2017): 15. http://dx.doi.org/10.9753/icce.v35.waves.15.
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This study investigates fatalities due to rip currents on the Black Sea coast of Istanbul. Results include the incidence rate of fatalities from rip currents, their causes, temporal and spatial distributions. The data shows that, nearly 70% of all drowning fatalities are associated with rip currents, and that on the average 33 people reportedly die from rip currents each year in Istanbul Black Sea coast. Thus, considering the wind speeds versus rip current fatalities, about one third of the fatalities occur when the wind speed is between 1.5-2.0 m/s. For the wind speeds 1.0-1.5 m/s the rip current magnitude is not too intense so people consider themselves capable enough to swim but for poor swimmers this is the most dangerous case. Nearly 60% of the fatalities in this wind speed interval is found to be children.
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Jalali Farahani, Rozita, Robert A. Dalrymple, Alexis Hérault, and Giuseppe Bilotta. "SPH MODELING OF MEAN VELOCITY CIRCULATION IN A RIP CURRENT SYSTEM." Coastal Engineering Proceedings 1, no. 33 (2012): 37. http://dx.doi.org/10.9753/icce.v33.currents.37.
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A Lagrangian numerical model called Smoothed Particle Hydrodynamics is used to analyze rip current system generated by a single bar and a rip channel. The pattern of the wave-induced circulation cell over the bar, the oppositely-rotating circulation cell on-shore and a strong seaward-directed current in the rip channel is modeled numerically. The mean horizontal variations of rip current system as well as three-dimensional circulations are studied. The results in three-dimensional space reveal the wave-current interaction and flow patterns in different parts of rip channel, bar, and the trough located near shore. For comparison to experimental data, Eulerian nodes are introduced to the numerical model and SPH interpolation over neighboring Lagrangian particles is implemented to find fluid parameters at those specific nodes. This methodology leads to a better understanding of depth-integrated flows and a more accurate comparison of numerical results with experimental results. Model predictions are compared to laboratory measurements of Drønen et al. (2002) and show good agreement, including mean velocity profiles, mean surface elevation and three-dimensional velocity components.
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Ishikawa, Toshinori, Ryo Shimada, and Tsutomu Komine. "ANALYSIS OF RIP CURRENT GENERATION USING AI-BASED DETECTION DATA." Coastal Engineering Proceedings, no. 38 (May 29, 2025): 35. https://doi.org/10.9753/icce.v38.papers.35.
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The occurrence of drowning accidents on beaches is mainly caused by rip currents. In this study, we created the AI model that can detect flash rip currents that occur intermittently in open areas. As a result of creating the AI model under various conditions, it was possible to detect the rip currents at each location with high accuracy at the stage of making the AI model. At the final point of the model’s evolution, the accuracy, the precision and the recall rates of the rip current detection were 88 percent, 17 percent and 100 percent, respectively. As a result of investigating the relationship between rip current detection results by the AI model and wave conditions, the characteristics of rip current generation on the study beach were able to be elucidated.
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Shimada, Ryo, Toshinori Ishikawa, and Tsutomu Komine. "PROPOSAL OF IMAGE PROCESSING FOR RIP CURRENT VERIFICATION." Coastal Engineering Proceedings, no. 38 (May 29, 2025): 66. https://doi.org/10.9753/icce.v38.papers.66.
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In Japan, rip currents are a major cause of drowning accidents, as many beachgoers fail to recognize them. Previous research has shown that visualizing rip currents can help users avoid them. While AI-based systems have been developed to detect rip currents from fixed-point camera images, these systems involve high initial costs for AI model creation and equipment. This study explores a cost-effective approach to visualizing rip currents using image processing and evaluates whether beachgoers can identify them effectively. The method involves calculating the difference between consecutive images, with areas of motion highlighted in green. Rip currents were identified by focusing on uncolored areas in the processed images. Data was collected over 45 minutes on three days when lifeguards confirmed the presence of rip currents. A total of 360 responses were gathered from 20 subjects who watched both original and processed videos, marking rip current locations. Accuracy was evaluated by comparing the subjects’ marked areas with those of lifeguards using the Intersection over Union (IoU) metric. Results showed no overall improvement in IoU when comparing processed and unprocessed videos. However, under sunny conditions, the IoU improved up to 62percent. In conclusion, this method can enhance beachgoers’ rip current verification in clear weather conditions which was considered a high number of users, potentially helping beachgoers avoid hazardous areas.
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Schlatter, Thomas. "Weather Queries: Rip Currents." Weatherwise 43, no. 3 (1990): 165. http://dx.doi.org/10.1080/00431672.1990.9927134.
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Cong, Nguyen Chi, Le Dinh Mau, Nguyen Van Tuan, et al. "Rip current simulation on some beaches in coastal Quang Nam province." Tạp chí Khoa học và Công nghệ biển 19, no. 3B (2019): 113–24. http://dx.doi.org/10.15625/1859-3097/19/3b/14519.
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This paper presents modelling results of rip currents on the main beaches along coastal Quang Nam province including Ha My, Binh Minh, Tam Thanh and Rang beaches during two typical wind seasons: Northeast monsoon (Northeast wind direction, wind levels: 4, 5, 6) and Southwest monsoon (Southeast wind direction, wind levels: 4, 5) using Mike 21 model. Calculation results show that during the Northeast monsoon, the rip current formed in all beaches. In the scenario of level 4 of wind speed, average rip speed was about 40–50 cm/s. In particular, at Tam Thanh beach area, the rip was a typical one with the components such as feeder current, rip neck and rip head. With the level 5 of wind field, the formation of the rip was clearer, the speed of the rip was stronger, average value was about 50–60 cm/s. Meanwhile, with the level 6 of wind field, the typical rip structure was broken, creating local eddies or longshore currents at some positions, but strengthened at other positions. During the Southwest monsoon, the rip current did not form at the beaches and the longshore currents were dominant.
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Hamsan, Muhammad Amirul Syafiq, and Muhammad Zahir Ramli. "Rip current occurrence probability at selected recreational beaches along Pahang coastline." Ecofeminism and Climate Change 1, no. 1 (2020): 37–50. http://dx.doi.org/10.1108/efcc-03-2020-0005.
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Purpose Pahang beaches draw more than thousand visitors throughout the year. From the year 2006 to 2018, more than 30 drowning and near-drowning cases were recorded mainly from rip currents. Rip currents are defined as unexpected currents that carried beachgoers away to seaward direction more than approximately 50 m from shore. The prediction of rip current development is very important for the protection of human life. This study aims to conduct preliminary survey and field works to identify rip current hazards. Design/methodology/approach The output would be an early warning preventative mitigation to public in Pahang. Beach state model, dimensionless fall velocity, littoral environment observation and relative tidal range were recorded for five recreational beaches during two different months (March and April 2018). The morphodynamic parameters such sediment fall velocity, sediment grain size and beach slope are then analysed using software PROFILER. Classification of risks was done based on beach morphodynamic model. The morphodynamics are classified as low tide bar rip, barred and low tide terrace associated with rip current, bar dissipative, reflective, non-bar dissipative, low tide terrace and ultra-dissipative. Findings Result shows three out of five recreational beaches may develop high-risk rip currents. During the first month of the survey, Batu Hitam (BH) was recorded the only one recreational beach that may develop high-risk rip current followed by Teluk Cempedak (TC) and Kempadang (KEM) as middle-risk rip current beaches, while Balok (BA) and Sepat (SEP) as low-risk rip current beaches. Different during second month of the survey, BA, BH and SEP were recorded as high-risk rip current beaches while TC and KEM as low-risk rip current beaches. Originality/value The results are consistent with beach incidents (drowning and near-drowning) reported.
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Liu, Yuli, Changming Dong, Xiang Li, and Fan Yang. "Assessing Rip Current Occurrences at Featureless Beaches Using Boussinesq Modeling." Journal of Marine Science and Engineering 13, no. 6 (2025): 1139. https://doi.org/10.3390/jmse13061139.
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Rip currents at featureless beaches (i.e., beaches lacking sandbars or channels) are often hydrodynamically controlled, exhibiting intermittent and unpredictable behaviors that pose significant risks to recreational beach users. This study assessed occurrences of rip currents under a range of idealized morphology configurations and hydrodynamic wave forcing parameters using a wave-resolving Boussinesq-type model. Numerical experiments revealed that rip currents with durations on the time scale of 10 min are generated in the forms of vortex pairs, intensified eddies, mega-rips, and eddies shedding from longshore currents. In general, the key conditions that promote rip current formation at featureless beaches include shoreline curvature, headlands, moderately mild beach slopes (e.g., 0.02–0.03), normal or near-normal wave incidence, and large wave heights. Most importantly, this study highlights inherent uncertainties in rip current occurrences, particularly under conditions usually perceived as low risk: low wave heights, short wave periods, oblique wave incidence, and straight shorelines. These conditions can lead to transient rip currents and pose an unexpected hazard that coastal communities should be aware of.
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Rampal, Neelesh, Tom Shand, Adam Wooler, and Christo Rautenbach. "Interpretable Deep Learning Applied to Rip Current Detection and Localization." Remote Sensing 14, no. 23 (2022): 6048. http://dx.doi.org/10.3390/rs14236048.
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A rip current is a strong, localized current of water which moves along and away from the shore. Recent studies have suggested that drownings due to rip currents are still a major threat to beach safety. Identification of rip currents is important for lifeguards when making decisions on where to designate patrolled areas. The public also require information while deciding where to swim when lifeguards are not on patrol. In the present study we present an artificial intelligence (AI) algorithm that both identifies whether a rip current exists in images/video, and also localizes where that rip current occurs. While there have been some significant advances in AI for rip current detection and localization, there is a lack of research ensuring that an AI algorithm can generalize well to a diverse range of coastal environments and marine conditions. The present study made use of an interpretable AI method, gradient-weighted class-activation maps (Grad-CAM), which is a novel approach for amorphous rip current detection. The training data/images were diverse and encompass rip currents in a wide variety of environmental settings, ensuring model generalization. An open-access aerial catalogue of rip currents were used for model training. Here, the aerial imagery was also augmented by applying a wide variety of randomized image transformations (e.g., perspective, rotational transforms, and additive noise), which dramatically improves model performance through generalization. To account for diverse environmental settings, a synthetically generated training set, containing fog, shadows, and rain, was also added to the rip current images, thus increased the training dataset approximately 10-fold. Interpretable AI has dramatically improved the accuracy of unbounded rip current detection, which can correctly classify and localize rip currents about 89% of the time when validated on independent videos from surf-cameras at oblique angles. The novelty also lies in the ability to capture some shape characteristics of the amorphous rip current structure without the need of a predefined bounding box, therefore enabling the use of remote technology like drones. A comparison with well-established coastal image processing techniques is also presented via a short discussion and easy reference table. The strengths and weaknesses of both methods are highlighted and discussed.
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Shimada, Ryo, Toshinori Ishikawa, and Tsutomu Komine. "STUDY OF METHODS FOR DETECTING OCCURANCE OF RIP CURRENT USING IMAGE ANALYSIS." Coastal Engineering Proceedings, no. 37 (September 1, 2023): 13. http://dx.doi.org/10.9753/icce.v37.papers.13.
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There are from 2,000 to 3,000 rescues every summer at bathing beaches in Japan, and the main cause of drowning accidents is rip currents. To analyze the rip current, a method for visualizing rip currents with average images can be used. However, in case of the investigation over a long period, such as several months, it is necessary to confirm the occurrence of rip currents through thousands of averaged images by human eyes. In this study, we suggested a new method for detecting the occurrence of rip currents automatically by analyzing the pixel values of averaged images. Images for the analysis were created from video data recorded in March and April 2021 by a camera overviewing the study beach located on the west coast of Japan. The accuracy results of this method were 99 percent for the validation dataset and 57 percent for the verification dataset, respectively. When the wave height was 0.5 m and higher for the verification dataset, the accuracy was 75percent. Therefore, it was considered that this method can detect the occurrence of rip currents when the wave height is 0.5 m and higher. As a result of applying this method to the 3-month image data recorded from October to December 2021, it was found that wave steepness was occurring lower under the conditions of rip currents. In conclusion, this method was able to automatically detect the rip currents from the images, and the conditions of waves when the rip currents that occurred could be investigated using this method.
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Deguchi, Ichiro, Mamoru Arita, and Takumi Yoshii. "FLUCTUATION OF RIP CURRENT MEASURED IN SHALLOW WATER REGION WITH SMALL TIDAL RANGE." Coastal Engineering Proceedings 1, no. 32 (2011): 44. http://dx.doi.org/10.9753/icce.v32.currents.44.
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Disappearance and formation processes of rip channel are discussed based on the field measurements of wave height, current velocity, bottom topography and flow pattern of near-shore current. Sudden increase in wave height together with the change in the wave direction took place during a half day caused these phenomena and rip current rose and fell according to the transition of the bottom topography. Furthermore, flow pattern of rip current was not steady but transformed itself with low frequency fluctuations of the period of few minutes. It is found that such low frequency fluctuations are caused by the intrinsic fluctuations of the incident waves (grouping waves) through the numerical simulations.
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Wang, Hsu-Min, Dong-Jiing Doong, and Jian-Wu Lai. "Rip Current Identification in Optical Images Using Wavelet Transform." Journal of Marine Science and Engineering 13, no. 4 (2025): 707. https://doi.org/10.3390/jmse13040707.
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Rip currents are fast-moving, narrow channels of water that flow seaward from the shoreline, typically forming within the surf zone and extending beyond the wave-breaking region. These currents pose significant hazards to swimmers, contributing to numerous drowning incidents, especially with the increasing popularity of ocean recreation. Despite their prevalence, rip currents remain difficult to detect visually, and no universally reliable method exists for their identification by beachgoers. To address this challenge, this study presents a novel approach for detecting rip currents in optical images using wavelet-based edge detection and image convolution techniques. Five identification criteria were established based on previous literature and expert observations. The proposed program incorporates image augmentation, averaging, and frame aggregation to enhance generalization and accuracy. Experimental analysis involving four iterations and four wavelet bases demonstrated that using two iterations with the Daubechies wavelet yielded the highest interpretation accuracy (88.3%). Performance evaluation using a confusion matrix further confirmed an accuracy rate of 83.0%. The results indicate that the proposed method identifies rip currents in images, offering a valuable tool for researchers studying rip current patterns. This approach lays the groundwork for future advancements in rip current detection and related research.
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Wahyudi, Vierda Khairene Tiffany, Yeyes Mulyadi, et al. "Morpho-dynamic Induced Rip Currents in Klayar Beach, Pacitan, East Java, Indonesia." IOP Conference Series: Earth and Environmental Science 1298, no. 1 (2024): 012035. http://dx.doi.org/10.1088/1755-1315/1298/1/012035.
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Abstract Klayar Beach (KB), Pacitan, East Java, Indonesia is a rugged coast with a narrow sand beach, a relatively small embayment with rocky headlands, and a very exotic view as a coastal tourism destination. Despite its attractiveness, KB poses a hazard due to rip currents. From 2009 to 2022, KB visited more than 3 million people, and more than 30 people were reported dead due to drowning in rip currents. This paper presents the result of fieldwork to investigate morpho-dynamic driven rip current hazard of the study area. This study carried out bathymetric and topographic mapping and sediment sampling. The last 10 years’ wave data was used for predicting hydrodynamic parameters. The study shows a good correlation between a variety of incoming significant wave heights and tide fluctuation vs. rip current velocity. The existence of headland plays a significant role in rip current formation in the study area. The headland influences either shadow or deflected rip currents formation for the incoming wave angle. The study also indicates that the type of rip current in the KB is structural boundary controlled, and the most important thing to be alerted for promoting beach safety in this area is that this rip current is predicted permanently to occur.
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Rampal, Neelesh, Christo Rautenbach, and Tom Shand. "INTERPRETABLE ARTIFICIAL INTELLIGENCE FOR RIP CURRENT DETECTION AND LOCALIZATION." Coastal Engineering Proceedings, no. 37 (September 1, 2023): 112. http://dx.doi.org/10.9753/icce.v37.management.112.
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A rip current is a strong, localized current of water which moves along and away from the shore. Identification of rip currents is important for both surf lifesavers/lifeguards when making decisions on where to designate safe swimming areas and for the general public when deciding on where to swim when lifeguards are on patrol. Our motivation is to enable better real-time detection of rip-currents to assist and improve decision-making and reduce the potential for loss of life. Our approach is to develop an artificial intelligence (AI) algorithm that both identifies whether a rip-current exists in a video or image, but also localizes where that rip-current occurs.
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Brander, R., D. Dominey-Howes, C. Champion, O. Del Vecchio, and B. Brighton. "Brief Communication: A new perspective on the Australian rip current hazard." Natural Hazards and Earth System Sciences 13, no. 6 (2013): 1687–90. http://dx.doi.org/10.5194/nhess-13-1687-2013.
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Abstract. Rip currents are strong, narrow offshore flows of water which occur on many of the world's beaches and represent a serious hazard to bathers. In Australia, rip currents account for an average of 21 confirmed human fatalities per year. Based on an analysis of the longest existing data records, rip currents account for more human fatalities in Australia on average each year than bushfires, floods, and cyclones combined. This finding raises important questions regarding the levels of attention placed on the low intensity, but high frequency rip current hazard in relation to high profile and episodic natural hazards.
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Choi, Junwoo. "A Numerical Study of Rip Current Generation Modulated with Tidal Elevations at the Daecheon Beach." Journal of Korean Society of Coastal and Ocean Engineers 34, no. 6 (2022): 247–57. http://dx.doi.org/10.9765/kscoe.2022.34.6.247.
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In order to investigate the generations of rip currents modulated with the tidal elevations at a mega-tidal beach at the West Sea coast, numerical simulations of rip currents over the topography of the Daecheon beach were performed by using a Boussinesq-type wave and current model, FUNWAVE. The mega-tidal coast includes rocky outcrops (i.e., reefs) lying over or under the water surface according to the tidal elevations in the offshore and nearshore bathymetry. The offshore topographically-controlled rip currents were well reproduced due to the alongshore non-uniformities transformed by the tide-modulated topography. This study addressed the generation types of rip currents to occur at the mega-tidal coast with the tide-modulated outcrops and reefs.
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Rui Qi, Rui Qi, Dao-Heng Zhu Rui Qi, and Xue Qin Dao-Heng Zhu. "Research on Rip Currents Detection Method Based on Improved YOLOv5s." 電腦學刊 34, no. 2 (2023): 113–27. http://dx.doi.org/10.53106/199115992023043402009.
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<p>Rip currents are common natural disaster and widely distributed on beaches around the world, which can quickly bring swimmers into deep water and cause safety accidents. Rip currents are generally sudden and insidious, making it difficult for inexperienced beach managers and tourists to identify them, and presenting a high risk to swimmers. Deep learning is a popular technology in the field of computer vision, but its applications in rip currents recognition are rare, and it is difficult to realize real-time detection of rip currents. In response to the above problems, we propose an improved YOLOv5s rip currents identification method. Firstly, a joint dilated convolution module is designed to expand the receptive field, which not only improves the utilization of feature information, but also effectively reduces the amount of parameters. Then, a parameter-free attention mechanism module is added, which does not increase the complexity of the model and can improve the detection accuracy at the same time. Finally, the Neck area of the original YOLOv5s model is simplified, the 80x80 feature map branch suitable for detecting small targets is deleted, and the overall complexity of the model is reduced by reducing the amount of parameters to improve the real-time detection. We have conducted multiple sets of experiments on public data set. The results show that compared with the original YOLOv5s model, the mAP of the improved model for identifying rip currents on the same data sets has increased by 4%, reaching 92.15%, and the frame rate has increased 2.18 frames per second, and the model size is only increased by 0.45 MB. Compared with several mainstream models, the improved model not only has a simplified structure but also significantly improves the detection accuracy, indicating that our model has the accuracy and efficiency in detecting rip currents, and can provide an effective way for embedded devices to perform accurate target detection.</p> <p>&nbsp;</p>
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Mucerino, Luigi, Luca Carpi, Chiara F. Schiaffino, Enzo Pranzini, Eleonora Sessa, and Marco Ferrari. "Rip current hazard assessment on a sandy beach in Liguria, NW Mediterranean." Natural Hazards 105, no. 1 (2020): 137–56. http://dx.doi.org/10.1007/s11069-020-04299-9.
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AbstractRip currents are one of the most significant environmental hazards for beachgoers and are of interest to coastal scientists. Several studies have been conducted to understand rip current dynamics, and several approaches for rip hazard assessment have been proposed. In general, the purpose is to provide knowledge and tools to support authorities and lifeguards in rip current risk prevention. This study proposes the application of an expeditious methodology to evaluate rip current hazard and risk, based on probability theory. The tested area was located along the Alassio beach, a renowned tourist destination located on the western Ligurian coast (NW Italy). A coastal video-monitoring system was used for rip currents individuation, whereas wave data were collected thanks to an oceanographic buoy managed by Regione Liguria. In detail, a yearly analysis was performed to identify the correspondence between rip currents and wave parameters data. The results showed that rip currents occur, in the study area, under moderate wave conditions ($$0.5 \le H_s \le 1.34$$ 0.5 ≤ H s ≤ 1.34 m; $$4.7\le T_m \le 7.0$$ 4.7 ≤ T m ≤ 7.0 s; $$150^{\circ }\,\hbox {N} \le \theta _m \le 227^{\circ }$$ 150 ∘ N ≤ θ m ≤ 227 ∘ N). Based on this analysis, an easy application of the probability theory was applied to evaluate the level of hazard. Moreover, considering the official tourist data, we also perform an expeditious rip currents risk evaluation. The results showed that the hazard level is considered high at annual time scale and moderate during the tourist season; the risk is related to seasonal presences. The study can propose a tool to support authorities and lifeguards in water safety planning and management.
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Yuan, Ye, Huaiwei Yang, Fujiang Yu, Yi Gao, Benxia Li, and Chuang Xing. "A wave-resolving modeling study of rip current variability, rip hazard, and swimmer escape strategies on an embayed beach." Natural Hazards and Earth System Sciences 23, no. 11 (2023): 3487–507. http://dx.doi.org/10.5194/nhess-23-3487-2023.
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Abstract. Drownings due to rip currents are a major threat to beach safety. In this study a high-resolution Boussinesq model with a modified wave-resolving Lagrangian tracking module has been applied to a 2 km long embayed beach, Dadonghai of Sanya, Hainan Island, with the purpose of studying rip current variability, real-time rip hazard identification, and the optimal swimmer escape strategies. The beach stage evolves periodically at the study site and plays an important role in the long-term modulation of the occurrence and strength of rip currents according to the modeling. A series of tests are designed and confirm that rip current strength is closely related to wave properties and tidal levels. Spectral analysis of output time series at specific points shows that the modeled rip currents fluctuate on the orders of 1 and 10 min, which suggests the effects of wave-group-forced infragravity (IG) and very-low-frequency (VLF) motions. Rip hazard levels are defined by combining rip strength and its duration. An attempt to use the GPU-accelerated FUNWAVE-TVD (Total Variation Diminishing version of the Fully Nonlinear Boussinesq Wave Model) embedded with the spectral wave model WAM6-GPU (GPU version of the third-generation spectral wave model WAM Cycle 6) exhibits its capability to evaluate rip hazard levels in real time. One of the differences of the present study from previous works is that the random, wave-resolving tracking of virtual swimmers is performed with 1 m resolution to study beach safety strategies. The results demonstrate that multiple factors contribute to the survival of swimmers caught in the rip currents, including surf-zone bathymetry, rip strength, fine-scale flow patterns, the bather's position, and swimming ability. For weak-to-moderate rip currents and longshore currents, swim onshore consistently seems to be the most successful strategy across all the scenarios in this study. Higher surf-zone exit rates along Dadonghai beach are not favorable for stay afloat action, which puts swimmers at a higher risk of being expelled to deeper water. The effects of wave randomness of incoming wave trains and assignment of wave-following coefficients on Lagrangian tracking are also discussed.
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Withers, Archie, and Sergio Maldonado. "On the swimming strategies to escape a rip current: a mathematical approach." Natural Hazards 108, no. 2 (2021): 1449–67. http://dx.doi.org/10.1007/s11069-021-04740-7.
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AbstractRip currents represent significant hazards to swimmers all around the world. The danger arises when a misinformed swimmer uses an inadequate strategy to escape the rip, such as fighting the current directly. This can lead to fatigue, panic, and in some cases drowning. There exists a range of strategies put forward by experts (both lifeguards and scientists) to escape rip currents. However, these recommendations are based on a limited number of scientific studies and there is still much discrepancy surrounding the best strategy to escape a rip. Thus, here we present a simple, physics-based theoretical model aimed at assessing different escape strategies in terms of their associated ‘energetic cost’ (in work and power) for any given rip current and swimmer’s proficiency level. Many combinations of swimmers and rips are considered, including both idealised and a realistic rip current. Our quantitative results back the common knowledge that swimming against the rip (which is strongly discouraged by lifeguards) is almost universally the worst possible strategy, especially when compared against strategies favoured by experts, such as floating with the current before attempting to swim back to the shore. For a realistic rip, our results suggest that swimming directly against the rip can require several times more power from the swimmer than other strategies advised by lifeguards, thus lending further scientific support to experts’ recommendations. This study may help promote education around the dangers posed by rip currents and how best to address them.
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Islam, Md Ariful, and Mosa Tania Alim Shampa. "Rip Current: A Potential Hazard Zones Detection in Saint Martin’s Island using Machine Learning Approach." ELCVIA Electronic Letters on Computer Vision and Image Analysis 21, no. 2 (2023): 63–81. http://dx.doi.org/10.5565/rev/elcvia.1604.
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Beach hazards would be any occurrences potentially endanger individuals aswell as their activity. Rip current, or reverse current of the sea, is a typeof wave that pushes against the shore and moves in the opposite direction,that is, towards the deep sea. The management of access to the beach sometimes accidentally push unwary beachgoers forward into rip-prone regions,increasing the probability of a drowning on that beach. The research suggestsan approach for something like the automatic detection of rip currents withwaves crashing based on convolutional neural networks (CNN) and machinelearning algorithms (MLAs) for classification. Several individuals are unableto identify rip currents in order to prevent them. In addition, the absenceof evidence to aid in training and validating hazardous systems hinders attempts to predict rip currents. Security cameras and mobile phones have stillimages of something like the shore pervasive and represent a possible causeof rip current measurements and management to handle this hazards accordingly. This work deals with developing detection systems from still beachimages, bathymetric images, and beach parameters using CNN and MLAs.The detection model based on CNN for the input features of beach imagesand bathymetric images has been implemented. MLAs have been applied todetect rip currents based on beach parameters. When compared to other detection models, bathymetric image-based detection models have significantlyhigher accuracy and precision. The VGG16 model of CNN shows maximumaccuracy of 91.13% (Recall = 0.94, F1-score = 0.87) for beach images. Forthe bathymetric images, the highest performance has been found with anaccuracy of 96.89% (Recall= 0.97, F1-score=0.92) for the DenseNet model of CNN. The MLA-based model shows an accuracy of 86.98% (Recall=0.89,F1-score= 0.90) for random forest classifier. Once we know about the potential zone of rip current continuosly generating rip current, then the coastalregion can be managed accordingly to prevent the accidents occured due tothis coastal hazards.
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Brighton, B., S. Sherker, R. Brander, M. Thompson, and A. Bradstreet. "Rip current related drowning deaths and rescues in Australia 2004–2011." Natural Hazards and Earth System Sciences 13, no. 4 (2013): 1069–75. http://dx.doi.org/10.5194/nhess-13-1069-2013.
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Abstract. Rip currents are a common hazard to beachgoers found on many beaches around the world, but it has proven difficult to accurately quantify the actual number of rip current related drowning deaths in many regions and countries. Consequently, reported estimates of rip current drowning can fluctuate considerably and are often based on anecdotal evidence. This study aims to quantify the incidence of rip current related drowning deaths and rescues in Australia from 2004 to 2011. A retrospective search was undertaken for fatal and non-fatal rip-related drowning incidents from Australia's National Coronial Information System (NCIS), Surf Life Saving Australia's (SLSA, 2005–2011) SurfGuard Incident Report Database (IRD), and Media Monitors for the period 1 July 2004 to 30 June 2011. In this time, rip currents were recorded as a factor in 142 fatalities of a total of 613 coastal drowning deaths (23.2%), an average of 21 per year. Rip currents were related to 44% of all beach-related drowning deaths and were involved in 57.4% of reported major rescues in Australian locations where rips occur. A comparison with international operational statistics over the same time period describes rip-related rescues as 53.7% of the total rescues in the US, 57.9% in the UK and 49.4% in New Zealand. The range 49–58% is much lower than 80–89% traditionally cited. The results reported are likely to underestimate the size of the rip current hazard, because we are limited by the completeness of data on rip-related events; however this is the most comprehensive estimate to date. Beach safety practitioners need improved data collection and standardized definitions across organisations. The collection of drowning data using consistent categories and the routine collection of rip current information will allow for more accurate global comparisons.
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Widartono, Barandi Sapta, Muchsin Nur Wachid, Deha Agus Umarhadi, Anggini Nur Azizah, and Restu Dwi Cahyo. "Kite Aerial Photography (KAP) for rip current identification in Parangtritis Beach." E3S Web of Conferences 76 (2019): 03005. http://dx.doi.org/10.1051/e3sconf/20197603005.
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Rip current is being the major cause of the deadly accidents in Parangtritis Beach. This occasion can be prevented by mapping and monitoring the spatial pattern of rip currents at the location which rip currents are located. Rip current location can be identified by remote sensing data or aerial observations, such as Kite Aerial Photography (KAP). This platform is low cost and can be performed in coastal area due to the massive winds there. KAP has been widely used as the platform for mapping, and some of them are implemented in coastal area. This study aims to find out the ability of Kite aerial photography to identify the rip current location in Parangtritis Beach. From several flight tests, the photo mosaic of Parangtritis Beach has been generated after the KAP has flown at the minimum 3 m/s of the wind speed. KAP can be the great potentials in coastal monitoring, especially for rip current monitoring because it is low-cost, low-energy and provides actual information.
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Kenyon, Kern E. "Rip Currents Have Least Friction." Natural Science 12, no. 05 (2020): 292–94. http://dx.doi.org/10.4236/ns.2020.125025.
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Vagle, Svein, David M. Farmer, and Grant B. Deane. "Bubble transport in rip currents." Journal of Geophysical Research: Oceans 106, no. C6 (2001): 11677–89. http://dx.doi.org/10.1029/2000jc000276.
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Takewaka, Satoshi, and Taishi Yamakawa. "RIP CURRENT OBSERVATION WITH X-BAND RADAR." Coastal Engineering Proceedings 1, no. 32 (2011): 43. http://dx.doi.org/10.9753/icce.v32.currents.43.
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X-band radar measurements were conducted at the research pier HORS, of the Port and Airport Research Institute, located in Hasaki, Japan. Ensembles of original radar images over 17 minutes were processed to time-averaged radar images every hour, which were analyzed to estimate the intertidal morphology and occurrence of rip currents. Several streaks extending in the cross shore direction appear in the averaged images which resemble to a neck and head of a rip current captured often in aerial photos or video imageries. The natures of these characteristic patterns in the time-averaged image are investigated through comparisons between optical images, floater release experiment and statistic analyses on sea conditions.
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Ghorbani, Ali. "The modelling of rip channel in creation of rip currents." Indian Journal of Science and Technology 5, no. 4 (2012): 1–5. http://dx.doi.org/10.17485/ijst/2012/v5i4.16.
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Moulton, Melissa, Gregory Dusek, Steve Elgar, and Britt Raubenheimer. "Comparison of Rip Current Hazard Likelihood Forecasts with Observed Rip Current Speeds." Weather and Forecasting 32, no. 4 (2017): 1659–66. http://dx.doi.org/10.1175/waf-d-17-0076.1.
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Abstract Although rip currents are a major hazard for beachgoers, the relationship between the danger to swimmers and the physical properties of rip current circulation is not well understood. Here, the relationship between statistical model estimates of hazardous rip current likelihood and in situ velocity observations is assessed. The statistical model is part of a forecasting system that is being made operational by the National Weather Service to predict rip current hazard likelihood as a function of wave conditions and water level. The temporal variability of rip current speeds (offshore-directed currents) observed on an energetic sandy beach is correlated with the hindcasted hazard likelihood for a wide range of conditions. High likelihoods and rip current speeds occurred for low water levels, nearly shore-normal wave angles, and moderate or larger wave heights. The relationship between modeled hazard likelihood and the frequency with which rip current speeds exceeded a threshold was assessed for a range of threshold speeds. The frequency of occurrence of high (threshold exceeding) rip current speeds is consistent with the modeled probability of hazard, with a maximum Brier skill score of 0.65 for a threshold speed of 0.23 m s−1, and skill scores greater than 0.60 for threshold speeds between 0.15 and 0.30 m s−1. The results suggest that rip current speed may be an effective proxy for hazard level and that speeds greater than ~0.2 m s−1 may be hazardous to swimmers.
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Xu, Jie, Sheng Yan, Zhili Zou, Chengshu Chang, Kezhao Fang, and Yan Wang. "Flow Characteristics of the Rip Current System near a Shore-Normal Structure with Regular Waves." Journal of Marine Science and Engineering 11, no. 7 (2023): 1297. http://dx.doi.org/10.3390/jmse11071297.
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Rip currents are the strong narrow seaward current produced by waves breaking on the coast. Of the many types of rip currents, the present study investigates, experimentally and numerically, the rip current system produced by the wave reflection on a finite-length shore-normal structure (corresponding to groin, jetty and headland in a real-word environment) with strong wave reflection strength. The incident wave condition of an obliquely propagating monochromatic surface gravity wave is considered for the bottom topographies of planar and barred beaches without or with a rip channel. The corresponding laboratory experiment was conducted and used to validate the numerical model. A set of higher order Boussinesq equations is used to reproduce the experimental observation and produce the results for the related prototype cases, with the latter considering more factors which may influence the formation and evolution of rip current flow patterns. The resulting rip current system contains two parts: the node rips formed due to the presence of the longshore standing wave in the wave reflection field and the deflection rip formed due to the interaction between the incoming longshore current and the reflection wave field mentioned above. A new formation mechanism of the deflection rip has been proposed, i.e., the deflection rip is formed by the meeting and then deflection of the longshore current and lateral flow. The effects of different wave reflection strengths of the structure, wave incident angles and bathymetric conditions on the pattern and flow volume of the deflection rip are also studied.
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Suarez, Leandro, Rodrigo Cienfuegos, Eric Barthélemy, Hervé Michallet, and Cristian Escauriaza. "LAGRANGIAN DRIFTER MODELLING OF AN EXPERIMENTAL RIP CURRENT." Coastal Engineering Proceedings 1, no. 33 (2012): 35. http://dx.doi.org/10.9753/icce.v33.currents.35.
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A non-uniform alongshore wave forcing on an experimental uneven mobile bathymetry create mean circulation on a rip channel. A 2D numerical hydrodynamic model that integrates the non-linear shallow-water equations in a shock-capturing finite-volume framework is used to validate the nearshore circulation, and drifters displacement.
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Stokes, Christopher, Timothy Poate, Gerd Masselink, Tim Scott, and Steve Instance. "New insights into combined surfzone, embayment, and estuarine bathing hazards." Natural Hazards and Earth System Sciences 24, no. 11 (2024): 4049–74. http://dx.doi.org/10.5194/nhess-24-4049-2024.
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Abstract. Rip currents are the single largest cause of beach safety incidents globally, but where an estuary mouth intersects a beach, additional flows are created that can exceed the speed of a typical rip current, significantly increasing the hazard level for bathers. However, there is a paucity of observations of surfzone currents at estuary mouth beaches, and our understanding and ability to predict how the bathing hazard varies under different wave and tide conditions are therefore limited. Using field observations and process-based XBeach modelling at an embayed, estuary mouth beach, we demonstrate how surfzone currents can be driven by combinations of estuary discharge and wave-driven bathymetric and boundary rip currents under various combinations of wave and tide forcing. While previous studies have demonstrated the high hazard that rip currents pose, typically during lower stages of the tide, here we demonstrate that an estuary mouth beach can exhibit flows reaching 1.5 m s−1 – up to 50 % stronger than typical rip current flows – with a high proportion (> 60 %) of simulated bathers exiting the surfzone during the upper half of the tidal cycle. The three-dimensional ebb shoal delta was found to strongly control surfzone currents by (1) providing a conduit for estuary flows that connect to headland boundary rips and (2) acting as a nearshore bar system to generate wave-driven “river channel bathymetric rips”. Despite significant spatio-temporal variability in the position of the river channels on the beach face, it was possible to hindcast the timing and severity of past bathing incidents from model simulations, providing a means to forewarn bathers of hazardous flows.
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Arun Kumar, S. V. V., and K. V. S. R. Prasad. "Rip current-related fatalities in India: a new predictive risk scale for forecasting rip currents." Natural Hazards 70, no. 1 (2013): 313–35. http://dx.doi.org/10.1007/s11069-013-0812-x.
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Fletemeyer, John, and Stephen Leatherman. "Rip Currents and Beach Safety Education." Journal of Coastal Research 261 (January 2010): 1–3. http://dx.doi.org/10.2112/09a-0005.1.
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Yu, Jie, and Siyu Chen. "Hydrodynamic Instability Mechanism for Rip Currents." Studies in Applied Mathematics 135, no. 2 (2015): 196–223. http://dx.doi.org/10.1111/sapm.12074.
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GRUSZCZYNSKI, MICHAL, STANISLAW RUDOWSKI, JULIA SEMIL, JAN SLOMINSKI, and JERZY ZROBEK. "Rip currents as a geological tool." Sedimentology 40, no. 2 (1993): 217–36. http://dx.doi.org/10.1111/j.1365-3091.1993.tb01762.x.
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