scholarly journals Rip current hazard assessment on a sandy beach in Liguria, NW Mediterranean

2020 ◽  
Vol 105 (1) ◽  
pp. 137-156
Author(s):  
Luigi Mucerino ◽  
Luca Carpi ◽  
Chiara F. Schiaffino ◽  
Enzo Pranzini ◽  
Eleonora Sessa ◽  
...  
Keyword(s):  
Probability Theory ◽  
Hazard Assessment ◽  
Rip Current ◽  
Rip Currents ◽  
Water Safety ◽  
Nw Mediterranean ◽  
Hazard And Risk ◽  
Nw Italy ◽  
Hazard Level ◽  
Ligurian Coast

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.

scholarly journals Correction to: Rip current hazard assessment on a sandy beach in Liguria, NW Mediterranean

2020 ◽  
Vol 105 (1) ◽  
pp. 157-157
Author(s):  
Luigi Mucerino ◽  
Luca Carpi ◽  
Chiara F. Schiafno ◽  
Enzo Pranzini ◽  
Eleonora Sessa ◽  
...  
Keyword(s):  
Hazard Assessment ◽  
Sandy Beach ◽  
Rip Current ◽  
Nw Mediterranean

Rip currents investigation on a Ligurian pocket beach, NW Mediterranean

2021 ◽  
pp. 107579
Author(s):  
Luca Carpi ◽  
Luigi Mucerino ◽  
Guido Bonello ◽  
Giovanni Besio ◽  
Marco Ferrari
Keyword(s):  
Rip Currents ◽  
Nw Mediterranean

Rip current rescues on unguarded beaches

Shore & Beach ◽  
2021 ◽  
pp. 41-45
Author(s):  
Aubrey Litzinger ◽  
Stephen Leatherman
Keyword(s):  
Young Person ◽  
Red Cross ◽  
Rip Current ◽  
Rip Currents ◽  
Water Ring ◽  
The U.S

Rip currents are the greatest danger at surf beaches. Professional lifeguards rescue tens of thousands of people every year at U.S. beaches, but only a small percentage of the nation’s beaches are guarded. Oftentimes it is a young person who is caught in a rip current, and a bystander will attempt a rescue without a flotation device. The U.S. Lifesaving Association strongly suggests that this kind of rescue should not be undertaken because too often the rescuer will drown. Some coastal towns such as Cocoa Beach in Florida are now posting ring buoys on their unguarded beaches with the warning to throw, but not to go into the water. Ring buoys of two different weights were tested for efficiency when thrown in terms of distance and accuracy. The participants threw the ring buoys two different ways: one way of their choosing (un-instructed) and second by Red Cross recommendation (instructed). The buoyancy was also tested for each buoy. While these flotation devices have some merit, they clearly have limitations.

scholarly journals Rip current evidence by hydrodynamic simulations, bathymetric surveys and UAV observation

2017 ◽  
Author(s):  
Guido Benassai ◽  
Pietro Aucelli ◽  
Giorgio Budillon ◽  
Massimo De Stefano ◽  
Diana Di Luccio ◽  
...  
Keyword(s):  
Grain Size ◽  
High Resolution ◽  
Numerical Simulations ◽  
Current System ◽  
Current Evidence ◽  
Rip Current ◽  
Rip Currents ◽  
Transport Pathways ◽  
Fine Sediments ◽  
Scientific Challenge

Abstract. The prediction of the formation, spacing and location of rip currents is a scientific challenge that can be achieved by means of different complementary methods. In this paper the analysis of numerical and experimental data, including UAV observation, allowed to detect the presence of rip currents and rip channels at the mouth of Sele river, in the Gulf of Salerno, southern Italy. The dataset used to analyze these phenomena consisted of two different bathymetric surveys, a detailed sediment 5 analysis and a set of high-resolution wave numerical simulations, completed with satellite and UAV observation. The grain size trend analysis and the numerical simulations allowed to identify the rip current system, forced by topographically constrained channels incised on the seabed, which were detected by high resolution bathymetric surveys. The study evidenced that on the coastal area of the Sele mouth grain-size trends are controlled by the contribution of fine sediments, which exhibit suspended transport pathways due to rip currents and longshore currents. The results obtained were confirmed by satellite and UAV 10 observations in different years.

scholarly journals AVALIAÇÕES DE RISCO EM BARRAGENS: ESTUDO DE CASO DA BARRAGEM MALCOZINHADO NO NORDESTE BRASILEIRO

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
Mariana Campos Fontenelle ◽  
Alexandre de Sousa Fontenelle ◽  
Yago Machado Pereira de Matos ◽  
Fernando Feitosa Monteiro
Keyword(s):  
Risk Assessment ◽  
Water Resources ◽  
Water Resources Management ◽  
The State ◽  
Management Company ◽  
Resources Management ◽  
Hazard And Risk ◽  
Hazard Level ◽  
Brazilian Northeast

RESUMO: O presente trabalho tem a proposta de avaliar a eficácia de duas metodologias de avaliação de risco de uma barragem no Nordeste Brasileiro no intervalo de 10 anos, baseando-se na inspeção e no nível de ameaça. Utiliza-se a metodologia Nível de Perigo da Barragem (NPB) para cálculo do nível de ameaça (Fontenelle, 2007) e para o cálculo do risco as metodologias da Companhia de Gestão dos Recursos Hídricos do Ceará (COGERH) e do Conselho Nacional de Recursos Hídricos (CNRH). Observa-se que o crescente número de barragens soma-se a preocupação com a segurança destas. Face a isto, utiliza-se a avaliação de risco como forma de priorizar ações de manutenção e recuperação. O estudo de caso ocorreu na Barragem Malcozinhado, localizada no município de Cascavel, no estado do Ceará. Com base na inspeção, calcula-se o nível de ameaça e o risco, compara-se estes com os resultados de 2006. Assim, observou-se o aumento no nível de ameaça, no entanto, o risco permaneceu, em geral, baixo, semelhante aos resultados de 2006. Este resultado se deve ao fato de que o número de anomalias aumentou, porém trata-se de uma barragem jovem, de pequeno porte e inspecionada regularmente.ABSTRACT: The present study has the proposal of evaluating the effectiveness of two methodologies of risk Assessment of a Brazilian Northeast dam in a range of 10 years, based on the inspection and the level of hazard. The methodology used for calculating the hazard level is the Dam Hazard Level (NPB). In addiction, in order to evaluate the risk is used the methodology of the Water Resources Management Company of Ceará (COGERH) and the methodology of National Resources Council Water (CNRH). The number of dams is increasing with to the concern for their safety. In view of this, risk assessment is used as a tool to prioritizing maintenance and recovery actions. The case study occurred in the Malcozinhado Dam, located in the municipality of Cascavel, in the state of Ceará. Based on the inspection, the level of hazard and risk is calculated, compared to the results for 2006. Thus, the increase in the level of hazard was observed, but the risk remained generally low, similar to 2006 result. This result is due to the fact that the number of anomalies has increased, but it is a young, small and regularly inspected dam.

scholarly journals A Bayesian network approach to modelling rip-current drownings and shore-break wave injuries

2021 ◽  
Vol 21 (7) ◽  
pp. 2075-2091
Author(s):  
Elias de Korte ◽  
Bruno Castelle ◽  
Eric Tellier
Keyword(s):  
Bayesian Network ◽  
Environmental Conditions ◽  
Surf Zone ◽  
High Energy ◽  
Environmental Data ◽  
Tidal Range ◽  
Boreal Summer ◽  
Rip Current ◽  
Rip Currents ◽  
Awareness Campaigns

Abstract. A Bayesian network (BN) approach is used to model and predict shore-break-related injuries and rip-current drowning incidents based on detailed environmental conditions (wave, tide, weather, beach morphology) on the high-energy Gironde coast, southwest France. Six years (2011–2017) of boreal summer (15 June–15 September) surf zone injuries (SZIs) were analysed, comprising 442 (fatal and non-fatal) drownings caused by rip currents and 715 injuries caused by shore-break waves. Environmental conditions at the time of the SZIs were used to train two separate Bayesian networks (BNs), one for rip-current drownings and the other one for shore-break wave injuries. Each BN included two so-called “hidden” exposure and hazard variables, which are not observed yet interact with several of the observed (environmental) variables, which in turn limit the number of BN edges. Both BNs were tested for varying complexity using K-fold cross-validation based on multiple performance metrics. Results show a poor to fair predictive ability of the models according to the different metrics. Shore-break-related injuries appear more predictable than rip-current drowning incidents using the selected predictors within a BN, as the shore-break BN systematically performed better than the rip-current BN. Sensitivity and scenario analyses were performed to address the influence of environmental data variables and their interactions on exposure, hazard and resulting life risk. Most of our findings are in line with earlier SZI and physical hazard-based work; that is, more SZIs are observed for warm sunny days with light winds; long-period waves, with specifically more shore-break-related injuries at high tide and for steep beach profiles; and more rip-current drownings near low tide with near-shore-normal wave incidence and strongly alongshore non-uniform surf zone morphology. The BNs also provided fresh insight, showing that rip-current drowning risk is approximately equally distributed between exposure (variance reduction Vr=14.4 %) and hazard (Vr=17.4 %), while exposure of water user to shore-break waves is much more important (Vr=23.5 %) than the hazard (Vr=10.9 %). Large surf is found to decrease beachgoer exposure to shore-break hazard, while this is not observed for rip currents. Rapid change in tide elevation during days with large tidal range was also found to result in more drowning incidents. We advocate that such BNs, providing a better understanding of hazard, exposure and life risk, can be developed to improve public safety awareness campaigns, in parallel with the development of more skilful risk predictors to anticipate high-life-risk days.

scholarly journals Open-channel landslide hazard assessment based on AHP and fuzzy comprehensive evaluation

2020 ◽  
Vol 20 (8) ◽  
pp. 3687-3696
Author(s):  
Xi Wang ◽  
Shuangyin Wang ◽  
Jiashuo Qi
Keyword(s):  
Water Supply ◽  
Hazard Assessment ◽  
Open Channel ◽  
Comprehensive Evaluation ◽  
Evaluation Model ◽  
Fuzzy Comprehensive Evaluation ◽  
Indicator System ◽  
Water Diversion ◽  
Comprehensive Evaluation Model ◽  
Hazard Level

Abstract Cross-regional water diversion projects usually face risks of hazards, in particular high risks of sudden landslides on the slopes of water supply open channels. Determining the hazard level rapidly after a hazard occurs plays a critical role in improving the efficiency of emergency response and recovering the water supply capacity of the projects. Through in-depth analysis of the factors that affect the severity of open-channel landslides, an indicator system for hazard assessment of open-channel landslides was established and the criteria for evaluation of different hazard levels were identified. Based on the hierarchy of the indicator system, a two-level fuzzy comprehensive evaluation model was established to assess the impact of indicators in the model on the hazard level of open-channel landslides, and the weight of each indicator was determined by the analysis hierarchy process. The linear function was used to calculate the membership degree of each indicator to determine the hazard level. A hazard scenario was created with the water diversion project from the Irtysh River to Urumqi as an example, and the two-level fuzzy comprehensive evaluation model was applied to conduct hazard assessment. The proposed method was confirmed to be reasonable and practical.

scholarly journals Public perceptions of a rip current hazard education program: “Break the Grip of the Rip!”

2017 ◽  
Vol 17 (7) ◽  
pp. 1003-1024 ◽  
Author(s):  
Chris Houser ◽  
Sarah Trimble ◽  
Robert Brander ◽  
B. Chris Brewster ◽  
Greg Dusek ◽  
...  
Keyword(s):  
United States ◽  
Online Survey ◽  
Social Research ◽  
Current Knowledge ◽  
The United States ◽  
Rip Current ◽  
Rip Currents ◽  
Safety Education ◽  
Large Area ◽  
Education Material

Abstract. Rip currents pose a major global beach hazard; estimates of annual rip-current-related deaths in the United States alone range from 35 to 100 per year. Despite increased social research into beach-goer experience, little is known about levels of rip current knowledge within the general population. This study describes the results of an online survey to determine the extent of rip current knowledge across the United States, with the aim of improving and enhancing existing beach safety education material. Results suggest that the US-based Break the Grip of the Rip!® campaign has been successful in educating the public about rip current safety directly or indirectly, with the majority of respondents able to provide an accurate description of how to escape a rip current. However, the success of the campaign is limited by discrepancies between personal observations at the beach and rip forecasts that are broadcasted for a large area and time. It was the infrequent beach user that identified the largest discrepancies between the forecast and their observations. Since infrequent beach users also do not seek out lifeguards or take the same precautions as frequent beach users, it is argued that they are also at greatest risk of being caught in a dangerous situation. Results of this study suggest a need for the national campaign to provide greater focus on locally specific and verified rip forecasts and signage in coordination with lifeguards, but not at the expense of the successful national awareness program.

scholarly journals Rip current related drowning deaths and rescues in Australia 2004–2011

2013 ◽  
Vol 13 (4) ◽  
pp. 1069-1075 ◽  
Author(s):  
B. Brighton ◽  
S. Sherker ◽  
R. Brander ◽  
M. Thompson ◽  
A. Bradstreet
Keyword(s):  
Incident Report ◽  
Anecdotal Evidence ◽  
Rip Current ◽  
Rip Currents ◽  
Actual Number ◽  
Time Period ◽  
Life Saving ◽  
The Us ◽  
The World ◽  
The Uk

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.

Rip current instabilities

2001 ◽  
Vol 433 ◽  
pp. 161-192 ◽  
Author(s):  
MERRICK C. HALLER ◽  
R. A. DALRYMPLE
Keyword(s):  
Linear Stability ◽  
Turbulent Mixing ◽  
Low Frequency ◽  
Variable Cross ◽  
Rip Current ◽  
Rip Currents ◽  
Jet Instability ◽  
Wave Forcing ◽  
Low Frequency Oscillations ◽  
Stability Model

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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