Keynote Lecture – The Interplay of Multiple Hazards and Urban Development: The context of Istanbul

Tomorrow’s Cities is the UK Research and Innovation (UKRI) Global Challenges Research Fund (GCRF) Urban Disaster Risk Hub – an interdisciplinary research hub with the aim to catalyse a transition from crisis management to multi-hazard risk-informed and inclusive planning in four cities in low-and-middle income countries. Istanbul in Turkey is one of the four cities investigated. It is one of the largest urban agglomerations in Europe where more than 15 million people reside in more than 1 million buildings. Considering that the population was 4.75 million in 1980, Istanbul’s urban sprawl was inevitable. Due to an imbalance between the population growth and housing supply, Istanbul’s urbanization was shaped by illegal construction processes producing the gecekondus in almost every part of the city (Gencer and Mentese, 2016). Unplanned urban expansion was so rapid that the urban master plan of 1980, which set the limits and strategies for urban development, became completely invalid by 1989 (Tapan, 1998). This situation led to the development of a new urban master plan in 1994 that included geoscientific analysis, and which highlighted the possibility of losses due to an earthquake on the segments of the North Anatolian Fault in the Marmara Sea. Uncontrolled and unplanned development continued in Istanbul until 1999 when two major earthquakes hit the region causing at least 18.000 deaths and $16 billion economic loss. These events changed the authorities’ perspective to earthquake risk and its mitigation. As a result, the 1998 earthquake resistant design code (published one year before the 1999 earthquakes) was widely embraced and implemented. Furthermore, several urban transformation projects have taken place in the last 20 years for reducing disaster risk. These have had varied success, with research to date showing that areas selected for urban transformation were often chosen on the basis of land value rather than hazard risk, and that a pro-poor approach is missing. Despite these efforts, Istanbul’s earthquake risk remains high. Furthermore, recent urban development plans are seeing the city expand into undeveloped lands to the west, increasing exposure to new hazards, namely flash flooding and landslides. The combined impact of these hazards is not evenly distributed, and the associated risks are heightened by poor infrastructural resilience and social vulnerabilities. Therefore, it is crucial to integrate different types of hazards and risks into the urban development context for future scenarios, so that a physically and socio-economically safer development that prioritizes the wellbeing of local communities can be facilitated. This presentation summarises the research conducted in Istanbul over the first 18 months of the Tomorrow’s Cities Project by a consortium of Turkish and UK researchers. This research spans the better characterisation of earthquake and landslide hazards, development of analysis methods for predicting the response of case study buildings to multiple hazards and a Bayesian network based approach for assessing road infrastructure resilience under multiple hazard scenarios. Furthermore, plans for building a Resilient Urban Development Decision Support Environment (RUD-DSE) for communicating the relevance of this research on future urban planning is described