Summary:

The work aimed at the determination of the silting degree and the silting forecast for water reservoirs at Brzóza Stadnicka and at Brzóza Królewska, which are situated on hydrologically uncontrolled Tarlaka stream. The analysis took into account the influence of upper reservoir - Brzóza Stadnicka - on the amount of se-diment flowing into the lower reservoir - Brzóza Królewska. The analysis of the silting process was carried out in three variants. The first one concerns to the Brzóza Stadnicka reservoir, the second to the Brzóza Królewska reservoir, without taking into consideration the upper reservoir, and the third variant took into ac-count the influence of the upper reservoir on the lower one. It was stated that stu-died small water reservoirs were characterized relatively low values of the sediment trap efficiency what causes extension of their useful life. Sediment trap efficiency of Brzóza Stadnicka reservoir determined on the basis of the balance of the volume of sediment delivered and deposited in this reservoir is carried out 27.9%. The somewhat higher value βrz = 38.7% the Brzóza Królewska reservoir is characterizes. It was also stated that the upper reservoir of the cascade had the in-significant impact on decrease of the silting intensity of the bottom reservoir. Ac-cording to the silting forecast worked out with the established value βrz, appointed on the basis of the sediment balance, the useful life of the Brzóza Królewska reser-voir will be enlarged from 192 years to 217 years. This shows on extension of the useful life of this reservoir only just about 15 or 13%.