Forecast of changes in the beach condition of the Yuzhne city under the influence natural factors

Abstract

The study of the factors of degradation and the forecast of the state of recreational areas of the coast to prevent their negative changes is relevant. Purpose. Forecast of changes in the condition of the Yuzhne beach, provision of general proposals for its protection from degradation. Methods. Mathematical statistics, linear analysis and mathematical modeling, comparative analysis, cartographic and grapho-analytical studies. Results. The beach of Yuzhne is located on the coast of the Black Sea. Its length is approximately 700 m. The southern direction in the sector 180±22.5⁰ is dangerous for waves. The distance from the beach to the opposite shore (wave acceleration) is 540-610 km. The boundary between the shallow and deep water zones is at a distance of approximately 200 km with a depth of 75 m. With southerly winds, recurring once every 25 years, on the approach to the shallow water zone with a depth of 50-75 m, a developed disturbance with extreme wave parameters is formed, which, transforming in the shallow water zone, significantly affects the coast. A profile of relative dynamic equilibrium with a length of 1,200 m and a depth at this distance of 11.2 m is formed during the calculated disturbance. From the water cut, the boundary between the near-cut and surf zones is located at a distance of 220 m with a depth of 3.6 m. Regardless of the standing water level, the calculated storm destroys the original shore at the extreme parts of the beach. When the sea level is high, the disturbance moves the destroyed material with the beach material into the cut-off zone, while the water cut at the 0.0 m BS mark does not change its planned location. The amount of beach material on the upper part of the coastal slope may decrease significantly. At an average level of the sea, the washing away of destroyed and beach material is accompanied by the advance of the water cut toward the sea for a distance of up to 20 m, but at the same time, a decrease in beach material on the above-water part of the coastal slope is also observed. Conclusion. Without taking special protection measures, the beach of the Yuzhne city will degrade in the future. In areas of the beach, in order to prevent its erosion, it is necessary to erect a retaining wall with a backfilling layer. An option for an active method of protection can be the construction of permeable bunkers on the beach or an intermittent breakwater at a distance from the shore. Such protection will not impede the alongshore transport of sand. Dunes or waves will contribute to the accumulation of sand on the beach. At the same time, after strong storms from the southern direction, with high sea level, episodic additions of sand to the beach are necessary

Keywords

• estimated wind speed
• wave mode
• wave parameters
• grain size composition
• dynamic equilibrium profile