MODELING OF FIERZA DAM SPILLWAY OPERATION AND DOWNSTREAM EFFECTS ON RIVER BED AND SLOPES

Abstract

This paper regards the case study of the two spillway tunnels of the 166.5 m high Fierza hydropower dam, in the Drini River, Albania, operated by KESH sh.a. since 1978. The analysis focused on both spillway tunnels and their jet flows impact on the river bed, bank slopes and on downstream flow conditions. The assessment of spillways operation under different discharge combination was performed by LNEC, Portugal. A 1:80 scale physical model and both 1D and 3D numerical models were applied. A set of recommendations for remedial measures to prevent observed slope instabilities and erosions was produced, as well as an evaluation the flow interference with the existing road bridge located approximately 500 m downstream of the dam toe. This paper summarizes the performed tests/simulations and respective results. Furthermore, it is intended to evidence the advantages of a combined approach using traditional hydraulic physical models together with novel CFD numerical models, which are growing in hydraulic structures applications.