THE DEGREE OF SILTING AND THE IMPACT ON ALLUVIAL DEPOSITS IN THE RIVER BEDS OF BISTRIŢA RIVER BASIN

Since 1960 the Bistriţa River basin came under the profound influence of anthropic incidence. This river basin represents a pattern of use for hydropower potential: reservoirs (9); channels (61 km); water dams; transfers of flows; protection structures works for banks and slopes; relocation of human settlements (13 villages); gravel pits; galleries; viaducts; communication paths, etc. Bistriţa River development has led to significant changes in the structure of the hydrological regime, through the regularization of water flows and by creating significant discontinuities in the transit of silt. Lately there has been an increase in water turbidity in the highlands. Solid flows on the lower course register a continuous decrease because of the existence of reservoir. During the execution of the hydraulic structures turbidity and sediment yield increased. When brought into service intense processes of silting occurred. Analysis covers the sediment yield in Bistriţa River basin and the evolution in time of the degree of silting of reservoir. Average production of silt varies between 1.5-2 t/ha/year. Annual rate of silting in reservoirs is between 0.6% (Izvorul Muntelui) and > 2% (Pângăraţi, Racova). Racova Reservoir was decommissioned in 2011