Quantitative Evaluation to the Sediment Load at a Part of Euphrate River in Center of Iraq

Abstract

Estimates sediment transport in Iraqi Rivers are essential for effective rivers management, particularly when delivery rates is potential threat to environment and ecological systems. Therefore , this research was performed for estimating sediment transport rates in a certain reach from Euphrates River downstream Al Hindiyah Barrage and examine the stat of Entrainment Rate Esi of bed sediments under a unsteady stream flow . Although of complexity and the difficulty of conducting measurements, the transport of suspended and bed load were measured with acceptable accuracy to obtain satisfactory results for monitoring the processes of transporting . Velocity profiles were measured by using an Acoustic Doppler Current Profiler ADCP and Using( Helley-Smith) sampler to collect bed load samples from 20 cross sections downstream Al Hindiya Barrage . The explore of vertical profiles of suspended sediment concentration include of evaluating the concentration near river bed using an Entrainment rate relation Esi, and the upward vertical distribution of particles in the water column. The measurement results are indicated the average suspended load is dominant mode of transport with average value 97.313 %.The observed suspended sediment yield in the river reach was ranged from 386.645 ton/day to 6588.58 ton /day during the drought condition and low level of water discharge and may change with discharge change. While bed load yield ranged between 0.270 ton /day to 5.394 ton / day. The result shows that near-bed entrainment, evaluated at 15% of the flow depth, decreases with the ratio of settling velocity to skin-friction shear velocity due to its role in determining bed load-layer concentrations. The fit relation for R2= 0.48 and correlation r= -0.55 indicates greater relation sediment diffusivities with greater flow resistance, likely due to bed-form induced turbulence, and larger the latter dependence is nonlinear.

Keywords

• euphrates river
• entrainment rate
• sediment transport
• skin-shear velocity
• particle reynolds number