The saltwedge intrusion in the Pregolya River as a reason for blocking the water intakes of Kaliningrad City

Intense wind surges redistribute the waters of the Pregolya River mouth and impede the operation of the water intake for the needs of Kaliningrad. The inability to withdraw water during long-term (more than 10-20 days) brackish water penetration can create problems with water supply. Data (2020-2024) on water supply shutdowns at the water supply station (reflected the intensity of brackish water wedge penetration upriver) showed an interannual increase in the number and duration of such cases. A comparison was made of the salinity measurements at a control point in the middle of the river mouth section with the chlorine data at the water intake. The considered examples of water supply shutdowns for 7-20 days in August and October 2023 made it possible to assess the conditions (wind exposure, water level rise and the initial position of the salinity wedge), which all facilitating the movement of wedge up to the water intake point. A regression relationship is proposed between the values of chlorinity at the water intake and salinity in the middle of the estuary of the Pregolya River, which, as a rst approximation, can be used to estimate the values of chlorinity at the water intake in the case of penetration of brackish water.