RECENT MORPHODYNAMICS AND CLOSURE IMPLICATIONS OF A NON-TIDAL INLET: LAZURNENSKA PRORVA, BLACK SEA COAST, UKRAINE

Abstract

Ephemeral inlets are important and specific components of the coastal barriers of the World Ocean. Withintidal coasts, the corresponding channels are called tidal inlets, and within non-tidal coasts – breaches (prorvas,promoiny, prorany). Ephemeral inlets are important for the development of coastal barrier systems. First ofall, they perform the function of hydrological control, determining the features and scale of water exchangebetween the water bodies adjacent to the barrier. The function of ephemeral inlets aimed at determining thevolume and direction of coastal and marine sediment movement is called geological control. The peculiaritiesof the movement of different species of plants and animals through ephemeral inlets are called ecologicalcontrol. In this context, the parameters of the studied inlets, the duration of their functioning, and thefrequency of closure and opening determine the specific conditions of the adjacent water bodies.Within the coastal barriers of the non-tidal seas, ephemeral inlets most often occur and function for along period of time within the accumulative forms of the Tendra-Dzharylgach system. The correspondingbarrier is characterized by a certain variety of prorvas associated with the hydrodynamic conditions ofthe adjacent water bodies.Among all the prorvas of the above coastal system, the Lazurnenska prorva is the most famous. Itshould be noted that this name should be understood as all ephemeral inlets that periodically appearedand functioned in the root part of the Dzharylgach Spit. Interest in the Lazurnenska prorva increased afternews of its artificial closure spread through a significant number of Ukrainian information resources.Information about the peculiarities of the emergence and functioning of the Lazurnenska prorva isbased on certain field materials from almost sixty years ago (Pravotorov I., Shuisky Y., Kotovsky I.,Vykhovanetz G., and Davydov O.). The available historical and cartographic material, which coversapproximately two hundred and thirty years, allows us to determine the frequency and duration of thefunctioning of the breaches. The available satellite images make it possible to determine the patterns ofevolution of the studied breach over a forty-year period. The Lazurnenska prorva has certain dynamic trends throughout the year. In the cold season, whenwaves and wind currents from the east and northeast dominate, the breach widens and deepens. In thewarm season, when waves and wind currents from the west and southwest become more active, thebreach channel narrows.In June 2022, it was determined that the studied prorvas was closed (based on satellite imagesanalysis). The analysis indicates that there is a natural tendency for the prorvas closure, but we do nothave reliable information on the main reason for the closure. At the beginning of June 2023, the breachhas been closed for a year. Under the conditions of long-term closure or artificial maintenance of thiscondition, very unfavorable consequences will occur within Dzharylgach Bay.