A three-dimensional numerical model is developed for incompressible free surface ows. The model is based on the unsteady Reynolds-averaged Navier-Stokes equations with a non-hydrostatic pressure distribution being incorporated in the model. The governing equations are solved in the conventional sigma co-ordinate system, with a semi-implicit time discretization. A fractional step method is used to enable the pressure to be decomposed into its hydrostatic and hydrodynamic components. At every time step one ÿve-diagonal system of equations is solved to compute the water elevations and then the hydrodynamic pressure is determined from a pressure Poisson equation. The model is applied to three examples to simulate unsteady free surface ows where non-hydrostatic pressures have a considerable e ect on the velocity ÿeld. Emphasis is focused on applying the model to wave problems. Two of the examples are about modelling small amplitude waves where the hydrostatic approximation and long wave theory are not valid. The other example is the wind-induced circulation in a closed basin. The numerical solutions are compared with the available analytical solutions for small amplitude wave theory and very good agreement is obtained.

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This paper presents a numerical modelling study into wind-induced currents in shallow water basins. A threedimensional, semi-implicit, finite difference numerical model is described, incorporating non-hydrostatic pressure, based on a sigma-transformed system in the vertical direction. The numerical model was first validated for sloshing in a rectangular tank; excellent agreement was obtained against analytical solutions, provided the nonhydrostatic pressure is incorporated. The model was further verified against experimental data on windinduced circulation in shallow rectangular tanks. It was then used to simulate wind-induced, three-dimensional flow fields in idealised rectangular tanks. A parameter study was carried out for wind-induced flows in Esthwaite Water, and the predictions compared against field data. It is shown that the numerical model is capable of accurately simulating the wind-induced circulation in shallow enclosed water bodies and that the topography and wind stress are of primary importance. The non-hydrostatic pressure does not have a significant effect on the windinduced flow fields considered herein.

In this paper, findings of a research project about river bridges in Turkey are shared and details of the developed safety-inspection method based on hydrological and hydraulic factors are presented. In the project, the Western Black Sea Basin was chosen as the pilot area, where the basin is mountainous with steep slopes and has a rainy climate with frequent flash floods. Many river bridges in the basin were inspected at different flow conditions throughout the project duration of three years. The developed safety-inspection method is composed of four main parts: evaluation of watershed hydrology and its flood potential, stream stability, bridge characteristics and a rapid scour assessment. A structural assessment is also included in the method. Five river bridges in the area were chosen for detailed inspection and application of the method. Results showed that the method was capable of identifying and ranking the bridges in regard to maintenance needs and forming a comprehensive inventory for bridge engineers.

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