Tridimensional nonhydrostatic transient rip currents in a wave-resolving model

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.

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

10.5194/nhess-2017-53 ◽

2017 ◽

Cited By ~ 1

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.

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