Hydrological congresses in the USSR attract large numbers of scientists and experts concerned with the study of surface and groundwater, the planning of water resource utilization and protection, and the design and operation of projects in water resources systems. These congresses represent important stages in the development of hydrology and in the assessment of the present state and determination of trends of hydrological research as applied to the needs of the economic and social development of Soviet society.
The Fourth Congress of USSR Hydrologists took place in Leningrad from October 9 to 13, 1973. It was attended by 1016 delegates and 374 guests, including 20 academicians and corresponding members of the USSR Academy of Sciences and of the Academies of Sciences of the Union Republics. There were 39 guests from Hungary, Poland, the German Democratic Republic, Czechoslovakia, Bulgaria, Romania, Yugoslavia, Mongolia, and Finland and also representatives of Unesco, WMO, the Danube Commission, and the International Association of Hydrological Sciences.