Storm water management in the İstanbul-Maslak example

Urban environments, where construction increases day by day, are turning into areas dominated by impermeable surfaces. Since this transformation causes the disruption of the natural water cycle, it brings about negative events such as floods and drought. Thus, cities are moving away from a sustainable life. In order to return cities to a sustainable life, natural cycles need to be improved. At this point, rainwater management comes into play. Unlike traditional rainwater management, progress should be made through sustainable rainwater management, which is a system that leaks water as much as necessary, collects it as much as necessary, and deals with how it can be used again efficiently. This new management approach consists of sustainable rainwater management units such as biological ditches, permeable surfaces and green roofs. It is observed that hard surfaces are increasing in many cities of Turkey, especially as the population begins to increase. Istanbul is one of the cities where hard surfaces are increasing rapidly. The natural water cycle in the city has begun to deteriorate. Within the scope of this thesis, Maslak, which is defined as a business center and dominated by high-rise buildings in Istanbul, has been determined as the study area. It is aimed to contribute to the natural water cycle by ensuring the rainwater management structure of the region. For this purpose, a 3-stage study was carried out in the Maslak region. The first stage is to calculate the amount of precipitation that flows in order to determine how much water needs to be taken under control. At this stage, the rational method, which is the most suitable calculation method for use in urban basins, was used. The amount of water flowing into the stream is calculated by multiplying the surface runoff coefficient, rainfall intensity and basin area according to the rational method. Permeable and impermeable areas were determined to be used in the method. Flow coefficients were determined according to the type of areas detected. Precipitation data obtained from the meteorological station closest to the study area were arranged according to the method. As a result of the studies carried out, the amount of precipitation flowing into the stream was calculated. The second stage consists of Multi-Criteria Suitability Analysis Based on AHP. In order to determine how much the slope, aspect and land use data prepared with GIS will affect the areas where runoff water will be collected, importance levels were assigned with AHP and the consistency of the values assigned to the criteria was tested. Accordingly, suitability analysis was obtained by superimposing the data via GIS. According to the analysis, a rainwater management setup was created with sustainable rainwater management units depending on the amount of water flowing in the most suitable areas. Within the framework of this fiction and in the light of the findings, design suggestions that can contribute to rainwater management on the scale of urban design and landscape architecture are presented for the study area.