Evaluation of flood performance of rainwater drainage systems

Precipitation regimes and behaviours change depending on the climate change. As the duration of precipitation decreases its intensity increases. Because the density of buildings increases in urban areas, drainage systems remain inadequate as a result of deterioration in the structure of natural streams and irregular structures. Urban floods lead to serious damage because of the change in precipitation behaviour and the decrease in permeable surfaces in urban areas. Stormwater drainage systems should be used for removing city floods safely. During the operation of such systems, the system does not work correctly and malfunctions due to many reasons such as incorrect hydraulic calculations, inability to determine the discharge points correctly, incorrect manufacturing and poor workmanship. In this study, it is aimed to analyse the flood performance of rainwater drainage systems currently serving in urban areas for precipitation with different repetition periods. For this purpose, the drainage line in Malatya provincial centre has been selected as the pilot application area. Considering the rainfall records observed in the past, a model was created for 5, 10 and 15 minutes of precipitation and 2, 5 and 10 years repetition periods. In addition, the digital elevation model, drainage line and characteristic information as well building layouts were taken into consideration in the application area. The flood analysis was done with the help of geographic information systems and InfoWorks ICM. As a result of the analysis, flood spread maps were prepared. It has been observed, the rainwater drainage line is insufficient in some areas, and may cause loss of property and life.