Іmprovement of protection dam of the мarine approach channel Danube-Black Sea

One of the important tasks for Ukraine is to restore navigation on the mouth of the Danube Bistre, using it as a European-Asian way from the Baltic Sea to the Black Sea, and then to the East. Restoration of the deep-sea navigation of the Danube-Black Sea River has begun about ten years ago and has been progressing with great difficulty and interruptions. A protective enclosing dam of the Maritime approach channel of the Danube-Black Sea deep-water vessel was built in the water area of the Bystre estuary of the Kiliya Delta of the Danube River. This paper presents the results of mathematical and physical modeling of the improvement and reconstruction of the protection dam of the Maritime approach channel of the Danube-Black Sea deep-sea navigation. Numerical calculations of the transformation of wind waves in the water area near the dam for the most dangerous wind directions in stormy conditions are carried out. For mathematical modeling, the maximum values of wind and wave height were used, which were observed during the entire research period in the area of the dam. Within the framework of refraction theory, wave transformation calculations were performed for the most wave-dangerous directions of wind acceleration, namely, northeast, east, southeast and south wind directions. The results of calculations show that the construction of a protective dam at the exit of the Bystre estuary leads to a significant reduction in wave heights (almost twice) and their lengths by more than 1.5 times, which will ensure a smooth approach and exit of vessels to the Bystre estuary. To assess the characteristics of storm surges and wind waves in the study area was set "hypothetical" storm, when uniform in space and constant in time wind blows over the entire Black Sea. Simulations of wind waves were performed by the 3-step method of nested grids. Calculations were performed for twelve options directly. The morphodynamic calculations showed the areas of circulating near bottom currents inside the dam protected area and the peculiarities of the bottom deformation due to wave motion and storm rise of sea level. Experimental studies on a fragment of the dam model revealed the areas of greatest wave loads, features of wave transformation and pressure fields on the dam ridge. On the basis of theoretical and experimental researches the new step form of the dam which withstands storm wave loads is proposed.