RUNOFF OF CARRIED RIVER SEDIMENTS AT THE BLACK SEA COAST,  KRASNODAR REGION 

V.A. Petrov ^1,* and N.A. Yaroslavtsev ¹

¹TsNIIS Joint Stock Co. Branch, “Sea shores” Research Center,
ul. Yana Fabritsiusa 1, Sochi, 354002 Russia.
^*E-mail: demmi8@mail.ru

Coastal protection measures carried out on the Black Sea coast of the Krasnodar Territory should be focused on the preservation of existing pebble beaches and the creation of wave-damping artificial beaches that meet recreational requirements. This fully applies to the pebble beaches located between Tuapse and Adler, experiencing huge anthropogenic load from the construction of recreational facilities and coastal protection structures that protect the railway from waves. When restoring lost beaches and creating new ones, solid river runoff must be taken into account, inaccurate data on which may negatively affect the recommended bank protection measures. Under natural conditions, before the construction of ports, coastal protection structures and sampling of alluvial sediments from rivers and beaches, the stable state of the beaches was ensured by the equality of the input and output components of the sediment balance in the coastal zone. In the inlet part, the main thing was the arrival of coarse-grained material on the coast, carried out by numerous streams. The expenditure component was determined by the abrasion of the beach material when moving under the influence of waves and, in part, by leaving the coastal section in the alongshore flow. The balance calculation permitted us to specify the runoff of the beach-forming material with a size > 2 mm from the rivers of the Black Sea coast, the Krasnodar krai, as sited in the works by G.N. Khmaladze [11] and, partially, V.V. Romashin [8]. Our calculations revealed overestimated solid runoff 2 times, by G.N. Khmaladze and 1.7 times, by V.V. Romashin. Anthropogenic interference with natural channel processes, i.e., channelling river beds and alluvium excavation has reduced the natural volume of sediments carried by rivers. The actual current solid runoff can be estimated proceeding from the volume of material accumulated in the coastal zone near river mouths, including buna complexes, in the interbuna compartments of which no beach-forming material was poured. Buna complexes located downstream of river mouths in the direction of the sediment flow accumulate sediments carried by rivers, which leads to the emergence and advancement of downstream erosion. A significant reduction in the solid river runoff causes an uneven distribution of the beach width along the coast, which is also associated with the construction of transverse barriers of unjustified length.

Keywords: sediment balance, groin, alongshore flow, abrasion of pebble sediments, beach, solid river runoff

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