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Congress: 2008
Author(s): Claudio Antonio Fattor
Hydraulic Engineer with specialization in hydraulic structures. Work place: Instituto Nacional del Agua, Casilla Correo 21 - (1802)-Aeropuerto Ezeiza, Buenos Aires, Argentina. Tel: (54-11) 4480-4500, Fax: (54-11) 4480-0433. Member of National Commission

Keyword(s): flood control, dams, Argentina
AbstractThe central region of Argentina is one of the zones that have been successively affected by floods that have caused severe economic losses, including losses of human lives. The province of Buenos Aires has been one of the most affected by this type of phenomena, but not the only one. In such sense, the southwestern area of the province of Córdoba has been seriously affected by floods of some of its main streams and rivers. In this general framework, flood control dams were projected and constructed on Las Lajas and Las Cortaderas streams, and on the River Quinto, by means of the financing of the Ministry of Federal Planning of Argentina. The objective of this work is to expose the general characteristics of these flood control dams, including hydrological, hydraulic and geotechnical criteria of the respective projects. From the methodological viewpoint, the hydraulic design of these three dams has considered the implementation of bottom outlets to regulate floods until 25 years return period. The uncontrolled spillways were designed to allow passing a flood related of a period of return of 1,000 years. In addition, the passage of the Maximum Probable Flood was verified, even though the freeboard could be highly diminished but always avoiding the surpass on the dam. Although there is not safety dams legislation in Argentina, the definitions before mentioned were reached by considering the type of dam, the reservoir volumes and the risk downstream of the dam. On the other hand, these civil works are located in relatively flatlands areas, being important to get an adequate hydraulic answer without drowning big areas under the maximum water level in the reservoir. This criterion leads to very long spillways, although the difference among the catchments and the peak flow discharges. For peak flow discharges related to 1,000 years return period of 505 m3/s, 550 m3/s and 950 m3/s for the dams of Las Lajas, Las Cortaderas and El Chañar respectively, the spillway lengths are 64,8 m, 80 m and 80 m, including the thicknesses of piles corresponding to each case. From the geotechnical point of view, the three dams are located on lime-sandy soils, which lead to project and construct earthfill dams with a revetment of soil-cement to protect its upstream side against the action of wind induced waves. This kind of revetment replaced the use of rip-rap because of the difficulty to obtain it in enough volumes and proper quality and dimensions. In conclusion, a series of flood control dams that will protect very important areas from the agricultural viewpoint and some populations located downstream of the respective dams were projected and constructed, being each structure designed with the same hydrological safety degree.
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