Formation and Re-Distribution of the River Runoff in the Catchment of the Pregolya River

The Pregolya River has a transboundary catchment between Russia, Poland, and Lithuania. The Pregolya River discharge is directed to two receiving reservoirs – the Vistula Lagoon and the Curonian Lagoon. In the article, the calculation of the volume of water flow rate from the Pregolya River catchment was made by numerical model. The annual average flows to the Vistula and Curonian lagoons constitute 1.96 and 1.2 km³/year, respectively, which in total gives 3.16 km³/year from the Pregolya River catchment towards the Baltic Sea through both lagoons. The contribution of Polish and Russian national areas to the annual river runoff was determined. The long-term seasonal mean re-distribution of the water flow to both receiving reservoirs (two lagoons) was analyzed. Average monthly values of water balance components for the entire catchment basin of the Pregolya River was drawn up, the annual average of 760 mm of precipitation is balanced by 530 mm of evapotranspiration and 230 mm of flow with surface runoff.