Salman Farsi Dam reservoir, a successful project on a karstified foundation, SW Iran

Abstract

The Salman Farsi Dam is constructed on the Ghareh Aghaj River at the northern limb of Changal Anticline, SW Iran. The anticline is composed of the calcareous Asmari Formation (AF) sandwiched between two marly formations, the Pabdeh–Gurpi (PGF) and Razak (RF). The AF is divided into three units: lower (LAF) marl and limestone, middle (MAF) karstified limestone, and upper (UAF) marl and marly limestone. The dam is constructed on the MAF, and the reservoir is in direct contact with the MAF, UAF and RF. A huge relict cave was discovered during excavation of grouting galleries in the MAF. In this research, the potential leakage passage (PLP) is defined as parts of the karst aquifer located lower than the normal water level (NWL) of reservoir, in which the reservoir water has potential to be leaked toward downstream, assuming no grout curtain construction. The PLP is composed of the inlet windows, transfer passage, and discharge zones. At the Salman Farsi Dam, the PLP is determined by three alternative schematic models considering hydrogeological and geological settings. At this dam site, the grout curtain was properly designed from the MAF toward the downstream LAF, at the narrowest part of the PLP and bypassing the huge cave. The grout curtain was successful in blocking the PLP based on the negligible leakage, and high differences between water level in the pair piezometers at the upstream and downstream sides of the grout curtain. It is recommended to determine the PLP in future dam construction in karst terrains.