Flood risk map in Istanbul: The most dangerous districts identified

Struggling with the effects of drainage issues and increasing urbanization, Istanbul's flood risks have been analyzed on a district-by-district basis in a study conducted by the ITU Disaster Management Institute. Developed in partnership with the Disaster Coordination Center (AKOM), this project applied an AI-based decision support algorithm, a first in Turkey. The risk map for the districts was updated by taking into account many indicators, ranging from population density to topography, and from vulnerability to exposure.

According to the research results, the districts of Fatih, Gaziosmanpaşa, Bağcılar, Güngören, and Beyoğlu ranked among the highest-risk areas for flooding. The districts with the lowest risk were identified as Adalar, Şile, Silivri, Sarıyer, and Çekmeköy.

Assoc. Prof. Dr. Ömer Ekmekcioğlu from ITU stated that they conducted the study using nearly 20 indicators in total and revealed the spatial distribution of flood risk in Istanbul in detail. "Approximately 15 different indicators were handled on a district basis in terms of hazard, while the rest were addressed in terms of vulnerability and exposure. With the collected data, we determined which areas are more sensitive across the city's vast surface," said Ekmekcioğlu, emphasizing that the risk has reached serious levels, especially in central districts.

EUROPEAN SIDE STANDS OUT

Ekmekcioğlu said that the flood hazard is more widespread on the European Side; he noted that districts such as Fatih, Gaziosmanpaşa, Bağcılar, Esenler, and Güngören have frequently experienced flooding in the past and that the risk is increasing due to the high population. On the Anatolian Side, while districts such as Üsküdar, Ümraniye, Ataşehir, and Kadıköy are more prominent, it was stated that the European Side generally carries a slightly higher risk.

"Approximately 10 percent of Istanbul's surface area was defined as a high-hazard zone, and 10 percent as a medium-hazard zone. Although the remaining areas appear to be low-risk, what is important is that this high-risk 10 percent slice corresponds to the city's highly populated districts. The probability of waterlogging and flooding is stronger here," Ekmekcioğlu assessed, drawing attention to urbanization and dense construction.

"NATURE-BASED SOLUTIONS ARE ESSENTIAL AGAINST FLOOD HAZARD"

Assoc. Prof. Dr. Ömer Ekmekcioğlu emphasized that the decrease in the city's natural areas and the spread of impermeable surfaces increase the flood risk, and he made the following recommendations:

"In large and crowded cities like Istanbul, emphasis must be placed on nature-based solutions. The expansion of rainwater harvesting systems, rain gardens, and permeable surfaces that allow water to pass into the ground should be a priority. Especially collecting rainwater on roofs can prevent water from flowing rapidly and turning into a flood. Implementing these practices is critical for both sustainable water use and reducing flood risk."

It was reported that the model developed using artificial intelligence takes into account meteorological and topographical factors as well as past flood events, thus being able to predict risky areas with an accuracy rate of 90 to 95 percent.

DISTRICTS WITH THE HIGHEST AND LOWEST RISK SCORES

Within the scope of the study, the districts of Fatih (0.7750), Gaziosmanpaşa (0.7505), Bağcılar (0.7340), Güngören (0.7305), and Beyoğlu (0.7211) were in the top five in terms of danger. The regions with the lowest flood risk in Istanbul were Adalar (0.1376), Şile (0.1377), Silivri (0.1831), Sarıyer (0.1880), and Çekmeköy (0.2212).

Experts state that urban planning in the coming period should be supported by scientific risk maps and the widespread adoption of nature-based practices.

News Source: 12punto