Scale Modeling of Riga HPP Stilling Basin

Abstract

Riga HPP was built in 1974, as the third and most downstream hydropower plant in a system of cascade dams on the Daugava River (Latvia). According to the design criteria at that time, all structures were designed to safely pass a discharge of Q_0.1%=7800 m³/s. Considering the fact that the capital city is located some 15 km downstream from the dam, it is considered a high-hazard dam. Current engineering trends recommend the application of a more stringent design criterion – all structures should be able to safely pass a discharge of Q_PMF=12800 m³/s. Scale model tests were aimed at assessing the possibility of passing the higher flood discharge through existing structures, by determining all the important hydraulic parameters in the study area. The project included a combination of numerical modeling of the downstream rating curve and physical modeling, and was carried out using a model on a scale of 1:60. The project provided not only important results, which should be very helpful in future maintenance, but also recommendations for improving the existing situation.