THE ANALYSIS OF THE SILTING PROCESS OF VÂRŞOLŢ RESERVOIR
OANA MOIGRĂDEAN
ABSTRACT. – The Analysis of the Silting Process of Vârşolţ Reservoir. The silting process of Vârşolţ reservoir has been monitorised beginning with the year 1983. The successive hydro-topometric surveys done in 1983, 1985, 1989, 1991, 1995, 1997, 2002, 2009 and the resulting data were reported to the initial morphometric characteristics of the lake, for the period 1979 – 2009 and to the one obtained out of the following topographic surveys. The methodology consists in determining the evolution of the silting of the Vârşolţ reservoir by calculating the characteristic volumes: dead volume, available volume, flash flood protection volume, above overflow volume, attenuation volume, global volume and the global volume corresponding to the height of the dam. The period 1979-2009 notes a global silting volume in the reservoir of 7,852 million m³, representing 16,43% of the initial volume. Analysing the silting of the characteristic volumes in the mentioned period one can notice that in the first 12 years (1979-1991) the process was very intense, and considerably diminished in the last 18 years (1991-2009). The determination of the sediment volume reaching the reservoir was done by means of the solid discharge measured at Crasna hydrometric station between 1981-2009. The volume of sediments accumulated in the reservoir resulting from the difference between the volumes at a normal service level in 1979 and 2009 is of 5.71 million m³. The silting degree corresponding to this volume is of 26,5%, with an average annual silting rate of 0,59%.
Key words: suspended load, characteristic volumes, silting rate, silting degree