Document Type : Research Paper

Authors

• Imzahim Alwan ¹
• Zahraa Majeed ²
• Ali S. Abbas ²

¹ Civil Engineering Department, University of Technology, Baghdad 10066, Iraq

² Civil Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq.

Abstract

This work aims to use the digital elevation model (DEM) or 3-Dimensional surface to model and analyze the water flow in the Tigris River. The first stage of this study is based on filed data acquisition survey at 38 stations.  These stations were adopted to implement the one-dimensional steady and unsteady numerical flow models. The HEC-RAS software was used to implement these models. The most important results of the steady-state model were that the maximum discharge and velocity and minimum flow area were 638.17 m³/sec, 2.12 m/sec and 301.42 m² respectively. These values occurred at station 66+700. While, the minimum discharge and velocity and maximum flow area were 504.5 m³/sec, 0.13m/sec and 4758.13 m² respectively. The results of unsteady state were analyzed based on the recorded discharge in the year 2018. The maximum and minimum discharge (flow velocity) were 638.12 m³/sec (2.42 m/sec) at the stations 94+666+7 and 635.57 m³/sec(0.14 m/sec) at station 00+00, respectively. The maximum and minimum Froude number were 0.52 and 0.02 at stations 94+666+7 and 04+800, respectively. These results help to identify the flow choking areas that cause defects. In addition, it can be the base for determining the critical sedimentation stations in which the bed level rises and aggravate the flow choking problem within the considered reach of the Tigris River.

Highlights

• Model has been operated to steady state based on the recorded discharge.
• Model has been operated to unsteady state based on the recorded discharge (2012-2017) years.
• HEC-RAS can use successfully for modelling the ecosystem behaviour of Tigris River within a steady area.

Keywords

• Tigris River
• DEM
• HEC-RAS
• simulation model