FLOW CONTROL DURING THE RIVER DIVERSION BY MEANS OF A PLANNED SEQUENCE IN THE OPERATION OF THE SPILLWAY COFFERDAMS

摘要

The project of Pichi Picun Leufu in the argentinian Patagonia was conceived a long time ago with little concern about environmental impact as was the trend in those days. The third stage of the river diversion process was thought counting on a complete closure of the river flow through a period of time up to 18 hours during which the reservoir increased its elevation in 10 meters for the water to resume flowing through the spillway crests. In such a long closure, the river would have diminished so bad its water contents that a damage could have been produced to the fish population. By means of a detailed study of the reservoir filling process and a very precise hydraulic operations with the spillway cofferdams, the flow was thoroughly controlled to reduce the closure time to 2 hours and a half avoiding, in this way, any damage to the fish. Collaterally, a careful study of the actual values, measured during the operation, allowed adjusting the data that were used as an input to the reservoir operation.