Coastal-marine sedimentation changes within lithodynamic unit of Berdyansk spit caused by anthropogenic impact

Abstract

The abrasive areas of Berdyansk lithodynamic unit have been investigated. It is revealed that cliffs are composed with rocks of IV and V class in their ability to resist abrasion and therefore are characterized by high destruction rates (1.2 to 3.2 m/year).

Taking into account the relevant abrasion rate, the coastal lithologic structure and certain layers of rocks, which are the source of the greatest number of coastal-marine sediments were analyzed.

The field studies of the coastal zone of Berdyansk lithodynamic unit were conducted in the period from 2007 to 2013. The body of Berdyansk spit and adjacent sites of indigenous coast have been examined. During the research the modern morphometry, morphodynamic and lithodynamic of the coastal zone have been analyzed and the anthropogenic landforms and their impact on the geological environment have been described, too.

The anthropogenic structures of shore protection and port destination within the coastal zone of Berdyansk lithodynamic unit were investigated. Geographical location of these structures, their qualitative and quantitative characteristics allowed us to identify areas with varying degrees of human transformation along the coastal zone of the studied region. The selected areas are characterized with local effects on certain parts of the coastal zone and transformation impact on the coastal area of Berdyansk lithodynamic unit.

More detailed studies have shown that at the present moment the internal alongshore sediments flow is greatly transformed and does not affect the dynamics of the spit. The external front sediments flow is weakened, and the distal sediments flow of biogenic material is intensively discharged within shore protection complex, consequently, this creates conditions for unequal distribution of clastic material along the middle and far parts of the spit.

It is determined that Berdyansk spit loses 34 618 – 140 110 m³ of coastal-marine sediments per year under various hydrometeorological conditions, that leading to destructive mode of the spit development.