Torrential downpours swept across northwestern Turkey on October 14, with three people killed as severe flash flooding hit Istanbul and neighbouring industrial hubs. At least four people were missing, with main commercial districts underwater.

State meteorological authorities issued orange and yellow alerts for 48 provinces ahead of a second weather front expected to sweep in on the evening of October 16. Turks were facing compounding logistical and financial pressure in restoring transport networks and draining flood waters.

The deluge, which delivered over 200 millimetres of rainfall per square metre in Istanbul districts such as Beykoz, Sariyer and Eyupsultan within hours, laid bare structural weaknesses in the foundations of roads and buildings built on river and stream beds in Europe’s largest city, a metropolis of more than 16mn.

Three dead, workers stranded in factories

Governor of Istanbul Davut Gul confirmed the death toll, reporting fatalities in Fatih, Sariyer and Kagithane and ongoing rescue operations in 14 locations across the megacity. Public schools were closed for a second consecutive day through October 16. Motorcycle delivery bans remained in effect, with all motorbikes in fact banned from joining traffic. Public sector workers were granted administrative leave.

In the northern industrial enclave of Ayazaga, dozens of workers were stranded in factories for over 14 hours as floodwaters rose up to three metres high, forcing rescue teams to employ heavy machinery and rubber dinghies for evacuations.

Cendere road – actually a riverbed

Key transit routes, including Cendere road in Kagithane on the European side of Istanbul, which connects central commercial nodes, were submerged, leaving hundreds of vehicles trapped in mud and debris.

“Dere” means “small river” in Turkish. Cendere avenue is actually the riverbed of the “Cen river” or “Kagithane river”.

Tweet: "The millennials are not aware that Cendere is actually a river, not a road."

Screenshot: Ihlamurdere ‘street’ in Besiktas.

Photo: ‘Vadistanbul’. “Vadi” means “valley”.

Transport chaos

Transportation systems across Marmara region suffered major disruptions. At Istanbul Airport, 43 flights were diverted to alternative airports, while operations at Sabiha Gokcen Airport located on the Anatolian side of Istanbul faced extended delays.

Runoffs from swollen rivers discharged into the Bosporus, visibly discolouring the strait’s coastal zones over a span of several hundred metres.

The storm system extended into neighbouring Kocaeli province, where overflowing streams inundated homes, businesses and critical freight arteries, including the D-130 highway.

Flooded EVs

The catastrophe is expected to trigger significant losses across the automotive, commercial manufacturing and insurance sectors. Automotive industry experts warned that flooded vehicles, particularly electric vehicles (EVs), present severe loss risks.

Screenshot: Vehicles "swimming" in Sariyer.

Hakan Dogu, head of the Sustainable Mobility Initiative in Turkey, told BloombergHT that water ingress frequently compromises high-voltage EV battery packs, which account for roughly 40% of an EV’s total build cost.

"When EV batteries suffer water damage, repair is rarely economically viable, leading insurers to declare total losses," Dogu warned, drawing comparisons to recent severe flooding events in Dubai that caused comprehensive motor insurance premiums to surge.

"We expect insurance premiums in Turkey to rise significantly in the wake of these localised disasters," he added.

Tweet: The 'stream' or 'dere' has risen.