Investigation of flow velocity distribution in open channels according to specific characteristics (under the effect of bed materials: sand, gravel, and concrete

Abstract

This study presents an in-depth experimental investigation into the effects of varying bed materials on flow velocity distribution in open channels—a critical consideration in hydraulic engineering and sustainable water resource management (Ab Ghani ,2018). Conducted within a controlled laboratory flume setup, the research examined how different sediment types, including vegetation (at varying lengths and arrangements), gravel (of multiple grain sizes), and sand (of different densities), influence hydraulic parameters such as flow velocity, discharge, water depth, hydraulic radius, and Reynolds number. Using flow current meters and hydraulic modelling principles, velocity profiles were produced for each bed condition using flow current meters and the concepts of hydraulic modeling.  The results show that bed material dramatically changes sediment transport dynamics, turbulence properties, and flow resistance.  Finer sands improved flow velocity because of their smoother surfaces and lower roughness coefficients, but vegetation increased flow resistance because of drag effects.  These realizations lay the groundwork for creating channel systems that are more effective and resistant to erosion.  These findings offer valuable insights for agricultural irrigation, urban drainage planning, and environmental hydraulics, with applications in sustainable water management and civil infrastructure development (Ohmoto, T. 2020).  . The results showed that sea sand achieved the highest flow velocity (0.284 m/s), while dense vegetation (25 cm spacing) and coarse gravel (14 mm) significantly reduced flow due to increased resistance. The Reynolds number ranged between 552 and 5371 depending on the material, indicating transitional to turbulent flow.