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A mathematical model of drift accumulation in an approach channel, which takes into account characteristic features of the interaction between the flow of drift and an enclosing structure, is proposed.The building of enclosing structures for marine ports is a classical means of protecting the approach channel and the water body surrounding the port from drift and penetrating swells. In practice, however, the effectiveness of enclosing jetties as protection from the accumulation of drift will be diminished during the time that the port is in service. Segments of an unprotected approach channel at the head end of the jetties may be subject to shoaling. This is expressed in a more rapid reduction in the depth of the waterway at the inlet to the port as compared with sections of the channel that extend further into the sea. Approach channels to ports, which are situated in shallow-water, sandy coastlines of seas with a developed along-the-shore drift flow. The ports are forced to conduct continuous and expensive dredging operations, since in the event that they are curtailed, the waterways will immediately lose their navigable depths. Moreover, continual dredging work in the channel significantly complicates navigation, and will result in monetary loss due to idling of ships.Observations and experimental investigations at the port of Temryuk on the Sea of Azov, and a port in the farming region of the Iron Horn on the Black Sea, which were conducted by the Moscow State Civil-Engineering University, as well as at the port of Ventspils on the Baltic Sea (Latvia) [1] enabled us to ascertain the character of drift accumulation in the approach channels protected by enclosing structures. The installation of jetties separates the shore zone into two regions with different dynamic activity relative to swells, currents, and drift movement. Rapid accumulation of large volumes of bottom sediments occurs as a result of overlap of an along-the-shore drift flow near the root section of the windward jetty (Fig. 1). This form of filling of the entry angler with drift, and subsequent flushing of the section of shoreline beyond the windward jetty is a common consequence of port construction.In the period of drift accumulation, jetties, as protection from drift accumulation, provide the expected effect at the entrance angle, and dredging operations are limited only to periodic scooping in the sea section of the channel. Further restructuring of the underwater relief will result in a drift flow past the head-end of the jetty under the action of the current along its external side. The drift that enters the channel here forms a clearly expressed cumulative cofferdam,

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