Hydraulic Model Development using HEC-RAS and Determination of Manning Roughness Value for Shatt Al-Rumaith

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Muthanna Journal of Engineering and Technology
Volume 5 issue 1, 2016

Ameera Mohamad Awad

Department of Civil Engineering , College of Engineering , University of Al- Muthanna ,  Iraq


Selection of appropriate Manning’s coefficient  is critical to the accuracy of computed water surface profiles.  Moreover ,  estimation of channel roughness parameter is of key importance in the study of open- channel flow particularly in hydraulic modeling .Hence, it is essential to calibrate the channel roughness coefficient for open channel whether natural or artificial   . In the present study ,  it is attempted to calibrate the value of  Mannnig’s “n”  coefficient by comparing the computed water surface profiles with observed one , using HEC-RAS steady flow model  for shatt al-Rumaith channel in Al- Muthanna   (Iraq ) . For this calibration  , the flows for the year 2014 has been considered .   It is found that the value of Manning’s roughness coefficient  for shatt al-Rumaith shows a good agreement between the computed with observed water surface profiles , is  n=0.023and   n= 0.04 for main channel and floodplain respectively


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