merged

Evaluation of Manning’s Roughness Formula for Coarse Bed River in
Terengganu
Muhammad Hafizzudin bin Muhammad Ali
Supervisor: Dr. Mohd Sofiyan Sulaiman
Bachelor of Technology (Environment)
School of Ocean Engineering
Universiti Malaysia Terengganu
Manning’s equation is important parameters in fluvial study to estimate river flows or
channel roughness in the river. Although Manning’s roughness n has been
documented in the past, it always unreliable due to the nature of river’s bed material.
This study was carried out to test existing formula on Manning’s n estimation at coarse
bed river for application. Pebble counting technique was implemented at Sekayu River
to develop grain size distribution and to estimate Manning’s roughness n. The actual
n was formulated using Manning’s equation of v = 1⁄ n × R 2⁄ 3 S 1⁄ 2 . It was found that
none of the existing equation on Manning’s n estimation can correctly predict actual
roughness n at coarse bed river. Therefore, future endeavor must be put in place to
find the best estimation equation on Manning’s n. The calculation on flood routing or
sediment transport in the river will be trustworthy should reliable Manning’s roughness
n are in place.
46 | U M T U N D E R G R A D U A T E R E S E A R C H D A Y 2019