Building Resilient Cities through Climate-Aware Urban Design: A Case Study for Istanbul

Istanbul is a coastal megacity with a population of more than 15 million inhabitants (2018), dispersed across more than 2,000 square miles of densely urbanized hills, valleys, riparian corridors, and coastlines. In the past half-century, Istanbul has experienced a rapid acceleration of urban development, adding to the region’s substantial energy and water demand, transportation system use, and environmental footprint at large. The megacity is enclosed between two water bodies, the Black Sea to the North and the Marmara Sea to the South, while the Bosporus Strait divides the city into two regions located in both Asia and Europe respectively.

Because of Istanbul’s dynamic topography, its long history of informal settlement (often at the edges of floodplains and riparian corridors), and its more recent waves of large-scale urban development, which have collectively added large swaths of impermeable surface area, the city is highly susceptible to both chronic and acute flood events. These flood events, which are likely to be further exacerbated by the effects of climate change, have exposed the need for more resilient stormwater infrastructure and management systems. In particular, the implementation of engineered urban wetlands may prove critical to Istanbul’s future planning and development. In spite of Istanbul’s clear stormwater imperative, major infrastructure projects of the past decade, which include a new regional airport (located in a former wetland area) as well as a proposed canal megaproject designed to relieve shipping congestion in the Bosporus Strait, have done little to address regional flooding.

In this study, the characteristics of historical flood events and the precincts most susceptible to flooding in Istanbul are investigated using available urban-scale geospatial data and meteorological observations. Past precipitation events which led to extreme flooding are investigated and simulated using a high-resolution regional climate model. Projected changes in mean and extreme precipitation rates are studied and urban design scenarios are generated with a focus on linking engineered stormwater wetlands to proposed redevelopment sites and infrastructure projects in the region. Finally, using the data analyzed improvements on the city’s existing stormwater drainage infrastructure and updates to building standards for climate resilient future infrastructure are offered.