Wall deflection in supercritical flow induces standing waves which significantly influence the flow field close to the wall. This paper analyses the flow in the converging stepped spillway, using two scale-models with different step heights and convergence angles. Results show that the height and the width of the standing wave increase with the increase of the convergence angle. Air concentration decreases while the air-water mixture velocity and residual energy head increase in the vicinity of the converging wall and gradually attain the values for the undisturbed flow outside the standing wave. Compared to the prismatic chutes of equal upstream width, converging spillways are less efficient energy dissipators. Equations for predicting the maximum flow depth and the width-averaged residual energy are proposed.

The performance of flat stilling basins can be inadequate for conditions when the tailwater depth is insufficient for hydraulic jump stabilization. In such cases, adverse-slope stilling basins can be used because they reduce the necessary tailwater depth. Sloped basins combined with smooth chutes have been the subject of many studies. However, limited research has been done for basins with stepped chutes, which are characterized by intensive flow aeration and high energy dissipation. Based on our scale-model experimental measurements of depth, velocity, and air concentration, we present a momentum-based method to characterize such hydraulic jump: the sequent depth ratio, the length of hydraulic jump roller, and energy dissipation effectiveness. The proposed method provides better agreement with experimental data when compared to existing methods and can be used for preliminary design.

Study of the behavior and transport of pharmaceuticals in groundwater is significant for understanding the processes of natural attenuation and potential use of filtration through the aquifer to evaluate the most effective way to remove pharmaceuticals that occur under anthropogenic influence. This paper presents the results of a field experiment at the location of the drainage system of Kovin-Dubovac in Serbia, during which a tracer test was conducted and the behavior of selected pharmaceuticals (trimethoprim, carbamazepine, diclofenac and metamizole metabolite N-acetyl-4-aminoantipyrine (4–AAA)) was monitored. The objective of the paper is to show and analyze the results of the tracer test, during which the tracer NaCl was injected, and to correlate the obtained characteristics of the subsurface and the breakthrough curves of the selected pharmaceuticals, so that the effects of sorption can be quantified. During the tracer test, the hydraulic head, flow, electric conductivity and concentrations of the pharmaceuticals were monitored continuously to collect sufficient data. The results show that sorption coefficients can be determined from experimental data and the NaCl breakthrough curve.

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