Seismic hazard and total risk analyses for large dams in Euphrates basin, Turkey: Fid-Bau Portal

Seismic hazard and total risk analyses for large dams in Euphrates basin, Turkey

Tosun, H. / Zorluer, I. / Orhan, A. / Seyrek, E. / Savas, H. / Türköz, M.

Turkey, which is located at the southeast of Europe, covers an area of 77.95 million ha. Almost one-third of this area (28 million ha) can be c1assified as cultivable land. Recent surveys indicate that an area of about 8.5 million ha is feasibly irrigable under the available technology. However, only 2.5 million ha land has been irrigated up-to-now. In other words, only 30 % of feasibly irrigable land is used. Turkey is also rich for producing hydroelectricity. Technically feasible hydropower is 36,260 MW. Only thirty-five percent of total capacity is used in Turkey now. Therefore, new investment for realizing water resources projects should be made to increase the irrigated area and electricity production within this decade. Reservoirs constructed near urban areas pose, however, a high-risk potential for downstream life and property. Turkey is one of the most seismically active regions in the world and has at least 1200 large dams with different types. Major earthquakes with the potential of threatening life and property occur frequently here. The Euphrates basin studied in this article is located in a seismically very active part of Turkey. The northern part of the basin is structurally cut by numerous faults. Many large dams are located on or close to these faults. In this paper the methods used for the analysis of seismic hazards and total risk are summarized. The seismic hazards of thirty-two large dams constructed on the Euphrates basin is discussed on the basis of the seismic activity of the dam site and their total risk as based on physical properties and the position in the basin. The seismic hazard analyses have indicated that peak ground acceleration changes within a wide range for the dam sites of the basin. A seismic hazard map showing the equivalent PGA (peak ground acceleration) values was developed so as to use for the preliminary analysis of dam structures, which will be designed in the basin. The total risk analyses depending on the seismic hazard rating of dam site and risk rating of the structure have concluded that fifteen large dams have high-risk class in the basin. These dams must be analyzed with high priority and redesigned to increase the safety of the embankments and their appurtenant structures, if necessary.