SEDIMENT TRANSPORT MODEL ING OF DOGNECEA RIVER, ROMANIA, CARAS SEVERIN COUNTY.

Study case is situated in Caras Severin County. Every sediment transport model application is different both in terms of time and space scale, study objectives, required accuracy, allocated resources, background of the study team etc. For sediment transport modelling, it is necessary to know the characteristics of the sediment in the river bed. Therefore it is recommended to collect a number of bed sediment grap samples. These samples should be analyzed in terms of grain size distribution. To solve theoretical problems of movement of water in the river Dognecea, it requires modeling of water flow in this case. Numerical modeling was performed using the program MIKE11. Advanced computational modules are included for description of flow over hydraulic structures, including possibilities to describe structure operation. MIKE 11 offers a variety of options for modelling of sediment transport dynamics and morphological changes in the river bed. Transport models are available for fine, cohesive sediments, such as clay and silt, non-cohesive sediments, such as sand, gravel and boulders, as well as mixed sediments. In a morphological model with dynamic feedback between the hydrodynamics, sediment transport and bed level and planform changes, the upstream sediment transport boundary condition is important. The longer the simulation period is, the more important the boundary condition is. Basically, two types of boundaries can be imposed: Bed levels or sediment transport rates at the boundary. The former is often applied, if it can be assumed with good approximation, that the bed level remains the same at the upstream boundary. The latter is applied, if specification of sediment transport (e.g. a zero transport) can be done accurately. [ABSTRACT FROM AUTHOR]