Document Type : Research Article
Department of Geology, Khoy Branch, Islamic Azad University, Khoy, Iran
Department of Water Science, Khoy branch, Islamic Azad University, Khoy, Iran
Study of the impact of bridge structures on the river floodplain using HEC-RAS and Arc-GIS software (Case study: Sarnagh Bridge on the Zola River)
Zola river is the most important fresh waters of West Azarbaijan province. The water surface of Urmia lake basin flows in this river. Sarnagh bridge is located on this river on the Sarnagh-Salmas road. Destructive flood event with high return time in river banks especially beside urban and rural residents cause to many financial damages and life threats. Thus investigate of rivers hydraulic behavior is essential. Research ahead studies the Zola river bed and realm boundary and its floods bond affected by bridges structure. This research studies the Zola River in Sarnagh road bridge position using HEC-RAS model. Firstly using river 1:2000 scale topographic maps, ArcGIS software with HEC -Geo RAS extension and HEC-RAS software, river discharge flow with 2, 5, 10, and 25, 50 and 100 return time were analyzed for two scenarios. First scenario simulates the river normal flow condition and second one simulate the river flow considering effects of cross over structure of bridges. Flow with 25 year return time has used to model design due to regional circumstances and controlled by 100 year return time flow, evaluating river bed extend before and after bridge structures. Results showed that narrow flow in bridge place cause to velocity reduction, flow reversal, deposition in upstream and velocity increase, erosion and foamin downstream of bridge that needs to construction of bed stabilization structure.
Keywords: Zola River, Hec_Ras model, River stabilization, Bed consolidati