Stages of Barriers Formation in the Entrance Gates of the Volgograd Reservoir Bays

Abstract

The secondary processes of alongshore transport and accumulation of sediments are the consequences of reshaping the shores of the Volgograd Reservoir. Alongshore sediment transfer promoted the segregation of bays from the main water area of the Volgograd Reservoir with abrasion-accumulative barriers. Classification of the bays according to the degree of evolution of abrasion-accumulative barriers in their entrance gates is the initial stage of complex research which is necessary to reveal the main patterns of the separation process. Application of the Earth remote sensing data and geoinformation technologies is the most effective to study the process in addition to field methods. The study is based on the satellite imagery of Google Earth program and data of field research of the bays in 2008, 2010-2016 and 2019-2020. Both analytical (cartographic, graphical, mathematical methods and methods of working with satellite images) and field (geometric leveling of abrasion-accumulative barriers and spits, and bathymetric survey of bays) research methods were applied. Morphometric parameters of the entrance gates to the bays of right and left coast of the Volgograd Reservoir were measured using the satellite images of Google Earth. Expedition materials and data received from satellite images were then compared. The difference in absolute values does not exceed double standard error. This indicates the reliability of applied research method. We calculated two coefficients for classification of bays. These coefficients considered width of the bay at the entrance gate, width of the coastal shallow water area at the entrance gate and length of above-water part of a sand bar or spit. Six classes of bays were identified according to the degree of evolution of abrasion-accumulative barriers at the entrance gates: opened bays (class 1), bays at the initial stage of segregation (2), bays at the active stage of segregation (3), bays at the final stage of segregation (4), closed bays, (5) and a specific class - bays with the entrance gates subjected to anthropogenic impact (6). The bay segregation becomes more active with the expansion of the coastal shallow water area at its entrance gate. Quick overgrowth by higher aquatic, herbaceous and tree-shrub vegetation takes place under the active formation of abrasion-accumulative barriers.