In this paper the two-dimensional depth-averaged momentum and continuity equations for steady shallow flow and sediment transport are described. This two-dimensional model is used to study of the bed deformation in alluvial channels. The perturbation of mean values in the cross-section of hydraulic flow parameters is determined by the periodic function which describes the non-uniform but steady flow. The function of this type allows the investigation of the flow stability in both: the straight and the curvilinear cannels. For these channels bed topography and horizontal distribution of depth-averaged velocity in longitudinal direction can be computed from exponential-periodic solution of the momentum and continuity equations. Bed topography computed from this solution is compared with bed topography of two bends in the Warta River. It was found that this solution is in good agreement with the measured bed topography in the river. It is also found that the cosine-generated curve is the natural curvature of the river meanders. Two equations for the calculation of the minimum value of meander curvature at the apex and the optimal length of bend are also presented in the paper. ...
The aim of the paper is to predict a morphological changes of the riverbed on a section of the Skawa River within back-water reach of Świnna Poręba water reservoir. The increasing bed level which is a result of deposition of bed material, have influence on water surface elevation during flood and can threaten surrounding areas. Between spring 2003 and summer 2006 carried out measurements which consist of: survey measurements of a section of Skawa River, granulometric composition of the bed material, velocity profiles and measurements of the water surface elevation during flood events. Prediction of the morphological changes was possible using twodimension CCHE2D model developed by the University of Mississippi. The numerical modeling focused on the simulation of historical flood events, t-year discharges with probability between p=50% and 0.1% under different water levels in the reservoir ranged between 304.56 m a.s.l - without back-water effect and 309.60 m a.s.l. - normal water surface level. The simulation runs included bedload and suspended load transport which caused of bed elevation changes. Back-water reach, where deposition take place, depends on reservoir water surface level can extend up to a distance about 1.5 km. Numerical results of forecasting of fluvial processes on the studied ...
The work concerns analyses of the water outlet through the hypothetical dam break in the dam of the dry reservoir „Rzymówka" on the river Kaczawa, which is currently in the project. One analysed two variants of dam erosion: overflowing water through the dam crest (variant 1) and hydraulic piping (variant 2). In the modeling one took into account different breach parameters based on parametric methods. The results of numerical simulation shows, that in case of the overflowing water through the dam crest will arise the dam break about width 74-78 m, and the duration of washing will be 0,8-2,1 h. However, if the dam break will be created as the result of the hydraulic piping, width would carry out 75 m. Magnitude of the water outflow through the gap has estimated on level 2337-2597 m3/s for variant 1 and 1590-2492 m3/s for variant 2. ...
