Flashfloods and Floods in Istanbul

Abstract

The city of Istanbul has been increasingly suffering from flashfloods and floods leading to loss of life and property for the last few decades. In this study, the causes of flashfloods and floods occurring in Istanbul were investigated from the perspective of the natural drainage system and urban development. Using Remote Sensing (RS) and Geographic Information Systems (GIS) technology, the natural flow accumulation, flow directions based on current slope characteristics, and contemporary aspects of the city were determined. Current constructions, and the characteristics of their distribution in Istanbul, were then associated with the results of the analysis. Constructions in Istanbul have played a major role by changing the natural character of the natural flow accumulation and flow direction, blocking the runoff, reducing water loss, and increasing the flow rate. Due to this, extraordinary rainfall occurring in Istanbul and its close vicinity causes flashflood and flood disasters directed and channelled by the many forms of construction in the city. To prevent future disasters or reduce their damage, the following solutions can be suggested. That all constructions interfering with the surface flow must be reclaimed with revised planning applications. The water-carrying capacity of drainage channels must be restored to their natural levels. That additional drainage channels taking into account natural slope conditions should be built. That aggregation of a huge water body which will cause flashfloods and floods must be prevented by means of a single channel.