Аннотация:An indicator to assess the possibility of effective water resources management of river systems, is proposed – the technogenic potential of river flow regulation. This is the ratio of the total value of the reservoirs useful volume in the river system to the volume of river flow during high-water phases of the runoff. It reflects the possibility of limiting catastrophic floods in river valleys by emptying the useful capacity of the reservoir in advance in cases of flood forecasting. Calculations were based on RIVDIS and GRanD databases. The rivers of Spain and Portugal are characterized by the highest values of technogenic potential of regulation (up to 100%), in Central Europe the river flow is insufficiently regulated (20-40%). The absence of deficit of technogenic potential of regulation is noted in the basins of the Syrdarya and Amudarya rivers, which are highly regulated upstream. The results of calculations for Western Europe, the European territory of Russia and the CIS countries are presented in the table and in the form of a map. The greatest technogenic potential of regulation is typical for river basins of arid regions (mainly due to the need to regulate flow for irrigation and water supply). The least technogenic potential of regulation is typical for the rivers of Eastern and Central Europe.