Dams, sediment sources and reservoir silting in Romania

Romania ranks among countries with the greatest achievements in the field of dams in the world. Among the 80 membership countries of the ICOLD, Romania ranks 19th in “large dams” and the 9th in Europe. The reservoirs arranged behind dams are characterised by small capacities, generally under 200 million mc. The total number of big dams is 246, among which almost half are dams under 40 m in height. The highest dam is Gura Apelor, on Râul Mare, in the Retezat Mountains and it is 168 m. We can add to these other 1500 dams, under 15 m in height, with the reservoirs having capacities under 1 million m3. The anthropic intervention through the arranging of dams and reservoirs in the river systems of Romaniaʹs territory is significant and justifies the concern of geomorphologists to know the relations between the dynamics of the landscape and the behaviour of these anthropic structures. ork refers only to one of the processes that reservoirs undergo once they are placed in a river system—the silting. More precisely, we try to make a synthesis of the knowledge stage of the reservoirs silting in Romania that we want to approach on the basis of the relations with our territory morphodynamics and considering the substantial accumulations of new data. The total erosion rate from Romaniaʹs territory is, on the average, 125 million tons/year out of which 45–50 million tons/year are transferred by rivers. lyzed 138 reservoirs with initial volumes between 1 × 106 m3 and 1230 × 106 m3 for which there is a determination of the silting time. The situation of the reservoirs silting from Romania is as follows: very serious for 15 dam reservoirs with average dimensions of 8 million m3, all of them situated in the Sub-Carpathian area, one of the important sediment production areas (over 500 tons/km2/year), with the silting time T50 of these reservoirs having values between 2 and 10 years; serious for 30 reservoirs, with average capacities of 35 million mc, and the silting time T50 between 10 and 50 years. In this case, the reservoirs are also situated in the area of important specific sediment production of over 250 tons/km2/year (the case of the rivers Olt, Argeş, Buzău, and Bistriţa but also of the reservoirs in the Bârlad basin), many of them being arranged as a cascade of small reservoirs on the main rivers; difficult for 13 reservoirs, with a silting time < 100 year and which are usually situated in the area at about 200 tons/km2/year.