Geoecological phenomenon in the lack of water conditions and regulation of the Don river

Over the seventy-year period of the Don river valley flood control under conditions of a lack of water climatic cycle, irreversible geomorphological and biogeocenotic transformations occurred in the drainage basin. As a result of persistent avalanche sedimentation, the Don delta and the seaside of the Taganrog Bay became shallow. During strong easterly winds, the seabed near Taganrog, from Port Katon and from Zaimo-Obriv is sewed over a distance of 5–10 km or more. In the winter of 2023–2024, a unique phenomenon of activity and accumulation of carp and sazan in the Don River delta was noted. Clearly abnormal mass accumulations of valuable commercial species, their early maturation, can be associated with the action of a complex of factors that were provoked by increased water discharge from the Tsimlyansk reservoir. The flow of water with fish mass along the Krivoe and Svinoe arms, at an extreme water negative setup, came up against a sandbar, which reflects the effect of shallowing of the Don River after 1952.