Floodplain analysis of Tigris river using HEC-RAS software

Floods are one of the reasons of the damages which occur as a result of natural disasters in the world. Because our country has regions which geographically have different structure and rainfall regime. It is sensitive to flood disasters when the state of nature is considered it is a weak probability to occur floods which is the biggest disasters after earthquake. But floods are becoming more risky for human beings day by day because of the population growth, need of water and settlements, wrong zoning plan and unplanned engineering practices. Rehabilitation comes at the begining of measures to be taken to minimize the damages that occur from the floods . To do these studies it must be specified the changes which bridges on the rivers and hydraulics structures like regulator cause in cross sections and the effects of the changes to water surface profile due to the natural state of the land. In order to determine water surface profiles, on the side todays methods there are many package software have been developed for facilitate in analyzing and calculation. HEC-RAS is one of them. In this study the floodplain analysis was handled between Diyarbakır-Silvan Highway and historical Ten Eye (On Gözlü) Bridge. Bridges over the Dicle River and the cross section changes caused by these hydraulic structures as wellas the facilities of the private establishments located on the route of the floodplain areas, which may occur together with determining the flow effect of the existing natural section changes. The facilities and hospitals connected to the university in the settlement of Dicle University, ten eye bridge(Dicle Bridge), Hevsel Gardens on the UNESCO World Cultural Heritage List, as well as the possible effects on the Dicle Valley project, which is considered to be done in the future years, have been tried to be determined. The 1/1000 maps of the study area were digitized using the AutoCAD Civil 3D program and cross sectional purchases were made by obtaining the digital elevation models of the region. The obtained cross sections were defined in the HEC-RAS software and the hydraulic characteristics of the flood bed and the water surface profiles of the Q25, Q50, Q100, Q500 flood recurring and one dimensional floodplain analysis of Tigris(Dicle) River were determined. According to the floodplain risk analysis results water surface profiles of flow rates Q25, Q50, Q100, Q500 were obtained.