Current circulation and sediment transport in the coastal zone in front of the Danube Delta

The objective of this study is to simulate, through an interaction of two mathematical models, the current circulation and sediment transport in the Northern part of the Romanian coastal area. The area of study has a length of about 34 km, North - South oriented, between the Sulina and Sf. Gheorghe branches of the Danube River, extending for about 30 km offshore. First a 3-dimensional hydrodynamic model of 5500 triangular elements is used to simulate the current circulation pattern at different depths in the proximity of the coastal area. Closer to the coast, the resolution of the element is about 200 m. Parameters used as data input were the bathymetry map of the studied zone interpolated with the grid, the wind stress calculated from real values using the formula of Smith and Banke and the liquid discharge of the Danube River. The sediment transport model, that aims to simulate the sediment dynamics, is coupled with the hydrodynamic one and forced by solid discharge and sea bed sediment characteristics. Three ideal situations considering the most frequent wind regimes have been carried out to better understand the general pattern of the circulation. The anti-cyclonal current described in literature could be simulated and analysed with particular meteorological conditions. Subsequently, real data measured in 2002 have been used to force a one year simulation. The results show the presence of seasonal differences in the erosion and deposition dynamics mainly due to different wind regimes.