The importance of water-sensitive planning and design approaches for resilience to flood disaster risk in Istanbul: Evaluation of examples in Çatalca and Beykoz districts

Nowadays, climatic changes are coming to the forefront of the global agenda due to their significant impact. Effects can be seen on rainfall and the hydraulic cycle, the number of disasters such as landslides, floods, and flash floods, which are especially increasing in cities. In recent times, flood and flash flood events have adversely affected many settlement areas in Istanbul. Istanbul, which is the main agglomeration of the country, has expanded spatially towards the urban peripheries due to population growth. The study focuses on the innovative basic principles of water-sensitive planning and design approaches for flood risk reduction, which have gained importance in light of international debates. In this context, the study examines the conditions for developing water-sensitive planning and design approaches in Istanbul and makes recommendations. For this purpose, a comprehensive and detailed literature review was conducted and scientific documents such as articles, international-national conventions, institutional research reports and national legislation were utilized. The study aims to determine the current situation in the areas where flood disasters occur in Istanbul, to identify the causes of the disasters, to question whether the land use decisions and urban planning approaches in the existing legal-administrative structure consider the risk factors for reducing flood disasters. Çatalca district, which is located on the urban periphery of the European side of the city, is very rich in water resources and is where the highest loss of life and material damage occurred in the flood disaster of 2009, was selected as the sample area in the study. Beykoz district, which is located on the periphery of the Anatolian side of Istanbul and very rich in water resources, was selected as another sample area. Within the scope of the study, data were obtained through interviews with relevant local institutions and organizations. Previous studies and existing data on the sample areas have been compiled and evaluated. When the practices of the institutions in the sample locations are examined, it is understood that the method of protection distances determined by legislation for the prevention of flood risk in stream beds is insufficient. In areas where flood risk is experienced, it is tried to be prevented by rehabilitation of streams. There is no holistic approach with planning decisions at the basin scale. As the population, settlement area and impervious surfaces increase in the basins where stream rehabilitation is carried out at high costs, these projects will be insufficient to prevent flood risk. Water-sensitive urban planning and design approaches with participatory and collaborative processes in basin scale should be start for resilience to flood disaster risk in Istanbul.