BEACH CUSPS ON THE ACCUMULATIVE COASTS IN THE SOUTH-EAST OF THE BALTIC SEA

The existing hypotheses of beach cusps development are considered. Their formation is the combined action of the beach abrasion and accumulation processes depending on the bottom slope, bottom sediments, and wave parameters. In recent decades, there are active debates about the origin of cusps. However, none of the hypotheses fully explains the mechanism of their formation. Thence the existing of some yet poorly explored hydrodynamic processes near the water edge having a significant impact on the cusps formation is supposed. A dynamic equilibrium of the beach at given seaway and the presence of rhythmic splash having sufficient force to move sediments of a given fineness are the main factors of the cusps formation. It apparently depends also on the type of wave breaking. Thus, the emergence of the cusps, their sizes and wave step are directly dependent on local morphodynamic parameters. Scalloped landforms are well represented along the shores of the Curonian and Vistula spits at the South-East Baltic Sea, and they are particularly unique in the lagoon shores. The combination of wind effected phenomena and wave action with of certain slopes of the coastal zone, leads to the development of a special type of acuteangled cusps with long “rumps” on the underwater slope. Long-term observations show that the cusps formation on the lagoon shores is quite possible and regularly re-starts under favorable conditions. At the spit shores different underwater slope parameters and seaway conditions lead to the development of the cusps significantly different from the lagoon’s ones. They are mainly the large forms with smooth contours and rounded tops.

1. Zenkovich V.P. Observations on beach cusps formation. Tr. In-ta okeanologii (Proc. Inst. Oceanolog.), 1948, v. 22, pp. 35–42 (In Russ.).

2. Gurjeva G.I. Concerning question of studying of beach cusps with radio methods. Tr. Laboratorii aerometodov (Proc. Lab. Aeromethods), 1955, v. 4, pp. 140–143 (In Russ.).

3. Egorov E.N. Observations on beach cusps. Tr. In-ta okeanologii (Proc. Inst. Oceanolog.), 1953, v. 7, pp. 117–125 (In Russ.).

4. Safyanov G.A. Geomorfologiya morskikh beregov (Marine coasts geomorphology). Moscow: Izd-vo MGU (Publ.), 1996, 400 p.

5. Johnson D.W. Beach cusps. Bul. Geol. Soc. Amer., 1910, v. 21, pp. 599–624.

6. Evans O.F. The classification and origin of beach cusps. Journ. Geology, v. 46, pp. 615–627.

7. Almar R., Coco G., Bryan K.R. et al. Video observations of beach cusp morphodynamics. Marine Geology, 2008, v. 254, pp. 216–223.

8. ?oco G., O’Hare T.J., Huntley D.A. Beach cusps: a comparison of data and theories for their formation. Journ. of coastal research, 1999, v. 15, no. 3, pp. 741–749.

9. Masselink G. Alongshore variation in beach cusp morphology in a coastal embayment. Earth Surf. Processes Landf., 1999, v. 24, no. 4, pp. 335–348.

10. Tsuguo S. A predictive relationship for the spacing of beach cusps in nature. Coastal Engineering, 2004, v. 51, pp. 697–711.

11. Inman D.L., Guza R.T. The origin of swash cusps on beaches. Mar. Geol., 1982, v. 49, pp. 133–148.

12. Kuenen P.H. The formation of beach cusps. Journ. geol., 1948, v. 56, pp. 34–40.

13. Zenkovich V.P. Osnovy ucheniya o razvitii morskikh beregov (Basics of the marine coasts development studies). Moscow: Izd-vo AN SSSR (Publ.), 1962, 710 p.

14. Zenkovich V.P. High tides influence on marine coast profile elements. Vopr. Geogr., 1954, v. 36, pp. 36–52 (In Russ.).

15. ?oco G. Murray A.B. Patterns in the sand: From forcing templates to self-organization. Geomorphology, 2007, v. 91, pp. 271– 290.

16. Allen J.R., Psuty N.P., Bauer B.O., Carter R.W.G. A field data assessment of contemporary models of beach cusps formation. Journ. of coastal research, 1996, v. 12, no. 3, pp. 622–629.

17. Seymour R.J., Aubrey D.G. Rhythmic beach cusp formation: a conceptual synthesis. Marine Geology, 1985, v. 65, pp. 289–303.

18. Holland K.T., Holman R.A. Field observations of beach cusps and swash motions. Marine Geology, 1996, v. 134, pp. 77–93.

19. Werner B.T., Fink T.M. Beach cusps as self-organized patterns. Science, 1993, v. 260, pp. 968–971.

20. Badyukova E.N., Zhindarev L.A., Lukyanova S.A., Solovyova G.D. Geology-geomorphologic structure of the Baltic (Vistula) Spit. Okeanologiya (Oceanology), 2011, v. 51, no. 4, pp. 1–8 (In Russ.).

21. Badyukova E.N., Zhindarev L.A., Lukyanova S.A., Solovyova G.D. Specifics of contemporary dynamics of lagoon shores of the Curonian Spit, the South-Eastern Baltic, in Sozdanie iskusstvennykh plyazhej, ostrovov i drugikh sooruzhenij v beregovoj zone morej, ozyor, vodokhranilishch (Proc. Intern. Conf. Novosibirsk, October 1-5 2011). Novosibirsk: Izd-vo SO RAN (Publ.), 2011, pp. 124–130 (In Russ.).