Determination of risk regions in drainage systems in urban areas: Malatya case study

In urban areas, floods occur in streams or channels due to various reasons. As a result of these floods, significant damages occur in settlements. Therefore, in order to minimize the damage of urban floods, it is important to investigate the factors that cause the flood and to determine the flood risk regions. In this study, flood simulation analysis was carried out for the natural channels in the urban area and a risk map of flood waters was formed. For this purpose, Horata channel in Malatya city center was selected as the application area. In the study area there are a total of four streams, which are likely to cause a flood risk. For these, the flood events observed in the past were investigated and the factors that cause it were evaluated. These factors are mainly related to the deterioration of the natural flow conditions, the degradation or complete elimination of the downstream conditions, the narrowing of the section for various purposes, improper zoning applications and insufficient sections. Flood hydrographs were obtained for 50, 100 and 500 year repetition periods for the Horata channel. Buildings along the channel route have been taken into consideration and defined as a separate layer. Infoworks ICM software was used for flood simulation and flood analysis was performed for different recurrence periods. As a result of the analysis, flood propagation maps were created for each case and the affected areas were determined. According to the results of these analyzes, the regions where the risk of floods are high can be listed as follows, especially where the natural flow is disturbed, the section is constricted for bridging, the areas where meandering are formed, regions where the section is insufficient.