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Go to Editorial ManagerThis research is an analytical study for simulation both sediment transport and flow within the Tigris river reach located downstream of the Al-Amarah barrage within the Maysan province. This study adopted a three-dimensional program (SSIIM) which use the Navier-Stokes equations for calculating the flow, and the convection-diffusion equations for calculating the sediment transport by the finite volume method as approximated method. A structured non-orthogonal three-dimensional grid is employed to perform the simulation. The obtained results are subsequently compared to the field measurements. The determination coefficient ( R 2 ) for this comparison is 0.96 for flow velocity distribution and 0.94 for sediment concentration distribution. The results also showed through the simulation of the water flow, the state of the secondary flow and its effect on both the main flow and the erosion of the river bed in the studied cross sections. According to the high convergence of the results of this model with the field measurements, this model is a powerful tool for simulating flow and sediment concentrations in river systems and channels.
Constructed wetlands are engineered systems used for wastewater treatment with the objective of reusing water under controlled conditions by mimicking natural treatment mechanisms involving porous media, plants, and microbial communities. This study investigates the performance of a horizontal subsurface flow constructed wetland, where wastewater flows through a gravel bed and vegetation roots, allowing contact with biofilm developed within the wetland substrate. To evaluate treated water quality, physical, chemical, and biological parameters were measured. Field results demonstrated that pollutant removal efficiency increased with detention time. After 3, 4, and 6 days of treatment, average removal efficiencies were 47.7%, 53.2%, and 77.5% for COD; 45.1%, 52.8%, and 64.4% for total nitrogen (TN); and 55.4%, 58.8%, and 72.2% for ammonium (NH₄), respectively. Nitrate removal averaged 19.41% after 3 days. These findings confirm that the horizontal flow constructed wetland system is effective in reducing key wastewater pollutants.