Design of the Rositas spillway, Bolivia

The design of the spillway for the 600 MW Rositas scheme was determined by several factors: the geomorphological conditions of the canyon, which is a relatively narrow valley, with steep slopes and a foundation of scarcely competent bedrock (soft sandstones); and, high design flows, which require a spillway of considerable proportions. In addition, the outflow discharge structure is relatively close to the powerhouse, so that it was necessary to ensure that the spillway will not affect power generation even during the most severe floods. The paper describes some innovative hydraulic solutions adopted, and the physical and numerical models used to verify the design features.