The Impacts of Sediment Transport on the Width of Ajichai River Flood Zoning

Document Type : Research Article


1 MA Student, University of Tabriz, Tabriz, Iran

2 Professor, Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran

3 Assistant Professor, Department of civil Engineering, Marand Faculty of Technical and Engineering, University of Tabriz, Tabriz, Iran


Flood zoning maps are among the basic and important sources of information for studying development projects in the world. In the conventional method of determining flood zoning maps, calculations are performed on the basis of a steady flow, assuming a fixed bed (without considering sediment transport). This study aimed to investigate the impact of river erosion and sediment transport on river flood zoning. So, the flood zoning calculations of Ajichai River were done using HEC-RAS model and the conventional method of steady flow with a fixed bed. In the next step, flood zoning calculations were performed using quasi-steady flow with moving bed and compared with the results of the previous step to determine the impacts of sediment transport on flood zoning. Comparison between the results obtained from steady flow (fixed bed) and quasi-steady flow with moving bed showed that in sedimentation sections, the width of the water surface increases in the flow mode with moving bed. The maximum rate of this increase in width is 19%. In other words, in the mentioned river, the width of flood zoning is less in the conventional method. This issue confirms the necessity of studying the river conditions in terms of erosion and sedimentation so that the amount of flood zone could be determined more accurately while the river is sedimentary. The increase of flood zone in sedimentation sections is due to the accumulation of sediments and consequently the increase of flow level and width of flood zonation. Therefore, it is suggested that in sedimentary rivers, a quasi-steady flow model (mobile bed) be used to prepare flood zoning maps for providing more safety.

Graphical Abstract

The Impacts of Sediment Transport on the Width of Ajichai River Flood Zoning


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  • Receive Date: 10 January 2022
  • Revise Date: 07 March 2022
  • Accept Date: 06 April 2022
  • First Publish Date: 06 April 2022