NEW Istanbul canal to link Black and Marmara Seas

To the west of Istanbul, between the Black Sea and the Marmara Sea, lie diverse landscapes of forest, farms, marshes and ancient settlements. Following a curving line from north to south would connect you through the Terkos Lake, Sazlıdere stream and reservoir and Küçükçekmece lagoon, important water sources for migratory birds – not to mention the city’s residents.

This line, however, is also the path of Kanal İstanbul, a $12.6bn(£9.7bn) mega-infrastructure plan described by President Recep Tayyip Erdoğan as his “crazy project” when he first mentioned the idea in 2011.

Kanal İstanbul, approved by the environment ministry last month, would be a 45km (28 mile) shipping canal joining the Black Sea to the Marmara, running parallel to the Bosphorus strait, which already cuts through the centre of Istanbul. The government says the canal is needed to reduce water traffic through the city.

Critics – who include the mayor of Istanbul – warn of a great environmental cost, including the potential ecological destruction of the Marmara Sea. There is a delicate ecological balance between the Black Sea and the Marmara Sea, currently connected by the Bosphorus strait.

Because the Black Sea is 50cm higher than the Marmara, both the level and salinity density would change if the two were connected by the canal. Not only that, the flow of cellular organisms into the Marmara would eat up extra oxygen.