Istanbul's Duplicate Image Crisis: The Key Decisions That Will Define the City's Digital Heritage

Thousands of photographs stored across Istanbul's fragmented municipal databases are duplicates — the same Bosphorus shoreline shot twice, the same Sultanahmet façade catalogued under three different reference numbers, the same earthquake-vulnerability survey image filed by both the Istanbul Metropolitan Municipality and the Disaster and Emergency Management Authority, known as AFAD. The scale of the overlap has quietly paralysed decision-making inside several city departments, and officials are now being pushed to act before the problem compounds further.

The urgency is not accidental. Turkey's urban digitisation drive, accelerated after the February 2023 Kahramanmaraş earthquakes exposed how poorly coordinated municipal records were, has produced a flood of scanned material without the data-governance rules to manage it. Istanbul's own Building Inspection Directorate has been uploading structural survey images since late 2023, often alongside identical files submitted independently by licensed inspection firms. The result is a growing archive in which no single record can be trusted as the authoritative version.

Where the Bottlenecks Are Forming

Two institutions sit at the centre of the problem. The Istanbul Metropolitan Municipality's Geographic Information Systems unit, based in Kagıthane, manages the city's master spatial database — a repository that now runs to several petabytes of imagery covering everything from Golden Horn industrial sites to the narrow yalı-lined streets of Arnavutköy. Separately, the Istanbul Directorate of Cultural Heritage and Museums, which oversees protected zones in Fatih, Balat, and the Princes' Islands, maintains its own photographic catalogue, inherited partly from the pre-2019 governorship structure. The two systems do not automatically communicate, and staff manually cross-referencing entries have flagged duplication rates that, by internal working estimates, affect a substantial share of recently ingested imagery.

The problem has a financial dimension. Storage costs on government cloud contracts in Turkey are billed in US dollars — a significant burden when the Turkish lira has lost roughly 60 percent of its value against the dollar since 2021, according to Central Bank of the Republic of Turkey exchange-rate data. Every redundant image sitting on a server is a recurring line item in a budget already squeezed by inflation running above 40 percent year-on-year as of early 2026, per Turkish Statistical Institute figures.

For heritage preservation, the stakes are sharper still. The Balat neighbourhood, a UNESCO-adjacent zone of Ottoman-era synagogues and Byzantine church remnants, is currently the subject of an EU-funded restoration programme running through December 2027. Project coordinators need a single, clean photographic baseline to document change over time. Competing duplicate records make that baseline impossible to establish with confidence.

What Happens Next

Three decisions are now unavoidable. First, the Metropolitan Municipality must designate a single authoritative archive — most likely the GIS unit in Kagıthane — and establish a formal data-transfer protocol with the Cultural Heritage Directorate. That process, if it follows the timeline of similar municipal IT consolidations in cities like Amsterdam and Barcelona, typically takes 12 to 18 months and requires a dedicated interoperability working group.

Second, an algorithmic deduplication tool must be procured and tested on a contained dataset before being applied to the full archive. The municipality's IT procurement rules require a public tender under Turkey's Public Procurement Law No. 4734, meaning a contract could realistically be issued by the fourth quarter of 2026 — but only if the political will exists inside the CHP-run administration to prioritise the spending.

Third, and most consequential, someone must determine the retention policy: which duplicate gets kept, which gets deleted, and whether deleted records are permanently purged or moved to cold storage. For earthquake-risk surveys covering districts like Avcılar and Zeytinburnu — both identified as high-priority zones in AFAD's Istanbul hazard assessments — the wrong deletion decision could erase the only surviving photographic evidence of a building's pre-survey condition.

The Balat restoration coordinators, the GIS directorate, and AFAD will all need seats at that table. The clock is already running.