Bosphorus

Bosphorus

Bosphorus

The Bosporus (/ˈbɒspərəs/) also Bosphorus (/ˈbɒsfərəs/, from Greek Βόσπορος, Bosporos; Turkish: Boğaziçi) is a strait that forms part of the boundary between Europe and Asia. The Bosporus, the Sea of Marmara, and the Dardanelles strait to the southwest together form the Turkish Straits. The world's narrowest strait used for international navigation, the Bosporus connects the Black Sea with the Sea of Marmara (which is connected by the Dardanelles to the Aegean Sea, and thereby to the Mediterranean Sea).
 
 
 
The limits of the Bosporus are defined as the connecting line between the lighthouses Rumeli Feneri and Anadolu Feneri in the north and between the Ahırkapı Feneri and the Kadıköy İnciburnu Feneri in the south. Between the limits, the strait is 31 km (17 nmi) long, with a width of 3,329 m (1.798 nmi) at the northern entrance and 2,826 m (1.526 nmi) at the southern entrance. Its maximum width is 3,420 m (1.85 nmi) between Umuryeri and Büyükdere Limanı, and minimum width 700 m (0.38 nmi) between Kandilli Point and Aşiyan. This part of the strait is a dangerous point for maritime traffic: a 45-degree course alteration is required, and the current can reach 7 to 8 knots (3.6 to 4.1 m/s). To the south, at Yeniköy, the necessary course alteration is 80 degrees. All the dangers and obstacles characteristic of narrow waterways are present and acute in this critical sea lane. At the above mentioned turns (Kandilli and Yeniköy) where significant course alterations have to be made, the rear and forward sights are totally blocked prior to and during the course alteration. Ships approaching from the opposite direction cannot be seen around these bends. The risks posed by geography are multiplied by the heavy ferry traffic across the strait, linking the European and Asian sides of the city.
 
The depth of the Bosporus varies from 13 to 110 m (43 to 361 ft) in midstream with an average of 65 m (213 ft). The deepest location is between Kandilli and Bebek with 110 m (360 ft). The most shallow locations are off Kadıköy İnciburnu on the northward route with 18 m (59 ft) and off Aşiyan Point on the southward route with 13 m (43 ft). The Golden Horn is an estuary off the main straits that acted as a moat to protect Old Istanbul from attack, as well as providing a sheltered anchorage for the imperial navy until the 19th century.
 
Most of the shores of the strait are heavily populated, straddled as it is by the city of Istanbul (with a metropolitan area population in excess of 12 million inhabitants) which extends inland from both coasts.
 
It has been known since before the 20th century that the Black Sea and the Sea of Marmara flow into each other in an example of a density flow and in August 2010 a continuous 'underwater channel' of suspension composition was discovered to flow along the floor of the Bosporus which would be the sixth largest river on Earth if it were to be on land. The study of the water and wind erosion of the straits relates to that of its formation. Sections of the shore have been reinforced with concrete or rubble and sections of the strait prone to deposition are periodically dredged.