Detection of changes over the long term for a series of hydrological variables is an important and critical issue, which is subject to increasing interest. In this study, trend analysis of the streamflow of the Euphrates basin, which is the biggest basin in Turkey, is carried out. The non-parametric trend tests (Mann–Kendall and Spearman's rho) are applied to annual average, minimum and maximum streamflow data of 22 selected stations in the Euphrates basin. All the streamflow records date back over at least 24 years, with lengths in the range 24–44 years. The Mann–Kendal rank correlation test is used to determine the year in which trends begin. The linear slopes of trends are calculated by using Sen's estimator of slope technique. Based on the test's procedures, with respect to annual minimum streamflow, significant decreasing trends are detected for six stations and an upward trend is found for only one station. While no trend appears relating to annual maximum streamflow for any station, a decreasing trend is found with respect to annual mean streamflow for one station. The results are expected to assist water resources managers and policy makers in making better planning decisions in the Euphrates basin.

The velocity field and surface profile of an open channel flow with a submerged hydraulic jump from a vertical sluice gate are investigated for two different flow cases. The governing equations are numerically solved using a finite-volume method for flows having the same conditions with experiments. The volume of fluid method is used to calculate the free surface. In modeling the turbulence stresses, standard k-ε, renormalization group k-ε, realizable k-ε, shear stress transport k-ω, and Reynolds stress turbulence closure models are employed. A grid convergence index analysis is carried out to determine the discretization error for the grid-independent solution. Experimental validations of the numerical results show that in predicting the velocity field, the Reynolds stress turbulence model is the most successful among the five. It also estimates the free-surface profile of the flow successfully.