NEW DATA ABOUT THE FUNCTION OF UNDERGROUND AND BLACK SEA WATERS IN THE AZOV-DON BASIN DURING THE LACK OF WATER PERIOD

The base of observations and conclusions regarding the modes of penetration of saline waters into the Don River delta have been significantly expanded. Water samples for hydrochemical analyses were taken from 20 November 2020 to 8 March 2021 at maximum positive and negative water surges. In some cases, samples in the river were collected in layers. Water was taken from the main water pipeline in the city of Azov. Purposeful sampling involved elucidation of the nature of ground, river and sea waters, their combination under surge conditions. The fixation of the material was carried out under normal conditions, extreme fluctuations in sea level, with a sharp increase of groundwater percent under ice, on a shallow seashore, in canals during negative surge. It was shown that in some delta branches, in the autumn-winter period, under conditions of eastern winds, lasting up to 2–4 weeks and at a speed of more than 6–10 m/sec, water exchange with the Sea of Azov and the navigable canal of the Don River is stopped. After the cessation of water connection, the channels are filled with groundwater. The evolution pattern of the types of stratification of sea and ground waters salinity in the Svinoe Arm of the Don River delta is constructed with alternating positive and negative surges. The reasons for the lack of water are explained, in which the missing volumes are compensated by the transfer of water from the Black Sea, which, in a transformed form, occasionally fill the Don River delta and enter the water intake systems of the city of Azov. In the Lower Don and Azov regions, there is a significant shortage of fresh water, including drinking water, in large cities. Many small rivers of the Azov region completely stop flowing during the warm period. In the face of obvious drought, all branches of agricultural production have to commensurate the need for water with the available water resources.

Don River delta, lack of water, climate change, ion composition, tide-surge phenomena, underflow