Bragado test case
Contents
Introduction
The Bragado Hydropower plant (HPP) is located in the North of Portugal, on the Avelames river, which is a tributary of the Tâmega river (Douro river basin).
The Avelames river is characterized by a strong seasonal variation in flow, with the highest discharge peaks occurring during the wet semester (October-March). Inter-annual variation in precipitation and, consequently, in runoff, is also large, as it is typical of a river with a Mediterranean flow regime. Mean long term annual discharge at Bragado weir amounts to 1.4 m3/s. The catchment area of the Avelames river at the section of Bragado weir is 78.8 km2. There are no other HPPs in the same river.
The water body at the HPP Bragado is classified as a natural water body with Good Ecological Status.
About the hydropower plant
Bragado is a run-of-river HPP with partial daily flow regulation. It has an installed capacity of 3.1 MW and a mean annual electricity production of 9.0 GWh. The small reservoir created by the weir has a useful storage capacity of 25000 m3 (total capacity of 34000 m3), located between the full reservoir level, FRL=495.1, and minimum drawdown level, MDDL=492.8. The weir was designed for the 100-year peak flood discharge of 230 m3/s.
The powerhouse of Bragado was designed for a maximum turbined discharge (or design discharge) of 2.2 m3/s and a net head of 155.2 m and it is equipped with one Francis turbine with horizontal shaft. The water permit of Bragado was issued in 1996, the construction of the scheme started in August 1997 and the first connection to the national electricity grid took place in December 1998.
