Istanbul residents, overwhelmed by the heat in the summer months, flock to the coast and beaches to cool off. The Bosphorus line and the Black Sea coast are the main choices of those who want to swim in the sea. However, those who want to swim in these regions may face the danger of currents. Swimming unconsciously in dangerous areas can also result in undesirable and sad events.
While surface currents are effective in the Bosphorus and rip currents (pulling currents) are effective on the Black Sea coast, it is stated that approximately 70 percent of drowning cases are caused by currents. Experts warn citizens not to enter the sea in these regions.
Assistant Professor Deniz Bayraktar Bural, Department of Shipbuilding and Ocean Engineering, Faculty of Naval Architecture and Ocean Sciences, Istanbul Technical University (ITU), stated that people want to swim in the sea to cool off and enjoy their vacation during the summer months, and this also brings about drowning cases. Bural stated that when drowning cases are examined statistically, 70 percent of the causes of death are due to the rip currents effective on Istanbul’s coasts opening to the Black Sea.
CURRENT SPEED AND STRENGTH INCREASE AT THE CURVED POINTS OF THE THROAT
Stating that the structure of the Bosphorus is slightly different, Bural explained that there is a 40-centimeter level difference between the Black Sea and the Marmara Sea and that due to the Black Sea being at a higher altitude, a surface current is formed from the Black Sea to the Marmara.
Pointing out that there is a double-layer flow in the Bosphorus, Bural said:
“There is another current flowing in the opposite direction towards the Black Sea, this time due to the difference in salinity at the bottom, that is, the Marmara Sea is saltier than the Black Sea. There is a double-layer flow. When we look at these currents, the reason is one level difference, the second This is a difference due to the salinity density. And when you look at the structure of the Bosphorus, the surface current speed increases considerably in narrow areas. This surface current then causes a countercurrent on some coasts where eddies and eddies form in the indented bays of the Bosphorus. “There are lanes. It is very dangerous to swim, especially at these points.”
ANOTHER DANGER FOR SWIMMERS IN THE BOSPHORUS IS SHIP TRAFFIC
Regarding the dangerous points to swim in the Bosphorus, Bural said, “In the most general sense, we can say this. There are faster, stronger currents in the places where the Bosphorus is narrowest. Where is this? Where is the Kandilli region, Rumeli Hisarı Akıntıburnu, where the currents are more pronounced?” Because the Bosphorus narrows and the water depth increases, there is a reverse current in the bay north of Üsküdar. Again, since there are geographically narrow and curved points, the water flows much faster around Çengelköy. “Similar currents can be observed.” shared his knowledge.
Pointing out that another dangerous issue in the Bosphorus, apart from the current, is ship traffic, Bural continued as follows:
“There is a very intense traffic in the Bosphorus. When very fast boats and yachts pass, the waves that form behind them reach the shore much more strongly. There is normally a danger. This is also a danger for the moored boats. “They may get damaged. There have been problems related to this in the past, caused by boats not complying with the speed limit. In this sense, of course, we need to be careful.”
“RIP CURRENTS IN THE BLACK SEA ARE MUCH MORE DANGEROUS THAN THE CURRENTS IN THE BOSPHORUS”
Stating that the rip current that is effective on the Black Sea coast generally drags it towards the open rather than pulling it to the bottom, Bural said that when the wind increases, the wave height increases proportionally, and rip currents are seen more frequently in such weather.
Bural noted that the rip current is effective on the sandy Black Sea coasts and that as the sand is carried in these regions, the sediment rises a little higher, the water becomes cloudy and foaming occurs, and continued his words as follows:
“When we look at the rip current, there is what we call ‘heel-dalyan-heel’, that is, a rift between two sand dunes. In such a bottom bathymetry, when the wave advances and breaks, it pulls back through that channel very strongly. The person is actually very intense, sudden. “The rip currents in the Black Sea are much stronger and more intense than any current in the Bosphorus. That’s why they are actually much more dangerous.”
“IT IS NOT SAFE TO SWIMM ON ANY COASTLINE WITHOUT A LIFEGUARD”
Bural gave the following warnings to those who want to swim in these regions:
“It is not safe to swim on any coastline where there is no lifeguard. We can observe this in wavy weather in areas where there are rip currents. If there is a sandy, heeled area on the Black Sea coast, we should avoid it. If it is a matter of entering the sea from the Bosphorus, they should remember that there are currents or that they can be exposed to a very different current two meters later. While it seems very close on the beach on one side, there may be a current two meters later. For this reason, it will be safer to enter the sea from coastlines where there are lifeguards or safety measures.”
Bural emphasized that swimming in the narrow parts of the Bosphorus or in areas where reverse currents form is dangerous even if one is a very good swimmer, and stated that it would be appropriate to swim by staying 1-2 meters away from the shoreline without going too far from the shore.
Giving information about what to do in case of being caught in a rip current, Bural said, “Let’s say we are caught in a rip current on the Black Sea coast. First of all, we should stay calmly on the water and wait without panic. Because at some point, the rip current will reduce its strength. Then, calmly, parallel to the shore, without trying to approach the shore. “We need to get away somehow.” he said. (AA)
