Effects of detached breakwaters on drowning due to rip and circulation currents

Rip currents are a hazardous phenomenon for beachgoers worldwide. These narrow currents in the surf zone move quickly in an offshore direction and can occur near hard structures such as jetties, piers, breakwaters, and rocks. This study examines the hazard rate (HR) for swimming in different water depths due to rip currents and coastal circulation currents (vortices), as well as the effects of detached breakwater structures on rip and coastal circulation currents (RACC) at the surf zone. The objective is to find a solution to the problem of drowning due to rip currents resulting from the presence of detached breakwaters. Physical and numerical modeling, field measurements, and shore surveying were used to achieve the study's goals. The study was conducted in the wave flume at Abu-Quire Research Station, Alexandria Egypt, for different scenarios. The numerical model (MIKE 21) was applied on the northwestern coast of Egypt about 21 km west of Alexandria. The results showed that the HR for swimming in water depths more than 1.50 m ranges from high to extreme hazard (1.275 m2/s: 2.2 m2/s), and the rip current velocities near the breakwaters are high, ranging from 0.05 m/s up to 1.05 m/s. Their length can extend from 30.0 m up to 200.0 m offshore. It was concluded that the RACC is caused due to the detached breakwaters, as well as the interaction between the boundaries and the beach bed. The proposed solution for RACC formations due to the presence of detached breakwaters is the partial closure of openings between the existing detached breakwaters using submerged breakwaters.