Coastal dynamics in the Narva bay of the Baltic sea: present-day state and development tendencies

Abstract

Central part of Narva bay is characterized by accretive coast, which is formed due to the presence of significant volumes of sand deposits. In the paper, the current state of coastal relief was analyzed and the forecast of its evolution under the prevailing wave climate was performed. The problem of the equilibrium of the coastal morphosystem for a given sediment budget and the probable trend of relative sea level was considered. Morphodynamic forecast for the period of the next decades was justified for designing the crossing of the coastal zone by the main pipeline route. Increasing of the role of accumulation processes from the south to the north has been identified through the field survey and analysis of satellite images, and has been shown by the nature of the beach relief and the underwater coastal slope. The calculation of the longshore sediment drift revealed the existence of a convergence zone for two differently directed sediment flows. Convergence of the sediment flows leads to accumulation of sand deposits at the rate of 19.0 m3 per one running meter per year. Estimates of the sediment budget resulted in the estimation of the accumulation rate at 8 m3 per one running meter per year in the coastal zone of area of the pipeline route. Sand accumulation leads to coastal accretion at the rate of 1 m per year. The obtained results lead to the conclusion on the stability of the coast in the coming decades unless the change of the sources of sand sediments and tendencies of its transport.