Andekaleka Gathering Tube Hydropower Intake

Tropical rivers often transport a heavy bed load and have a high silt content, and their surface waters carry leaves, twigs, and an occasional tree or branch. Extracting reasonably clean water for a high head power plant usually requires the installation of sand traps, sediment sluices, and leaf skimmers. This paper describes the work associated with the development and hydraulic model testing of a unique gathering tube intake built into the diversion dam of the 112 MW, 702 ft (214 m) head hydropower development at Andekaleka on the island of Madagascar. River water is extracted from the relatively clean mid‐flow level, above the bed load and below the contaminated surface waters. Results from an inspection after two years of operation are presented, along with a comparison of model and prototype performance.