Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Fishpass Design of the Xayaburi Hydroelectric Power Plant, Laos (#185)

Michael MRR Raeder 1 , Thanasak Poomchaivej 1
  1. Ck Power Public Company Limited, Bangkok, THAILAND, Thailand

The Xayaburi project was the first run-of-river hydropower plant built on the Lower Mekong River and is now in operation since the end of 2019.

It was particularly challenging to design the Fish Passing Facilities since no direct references and only very little data were available in the initial design phase. Therefore, the developer Xayaburi Power Company Limited (XPCL) carried out a number of fish studies to design and optimise the Fish Passing Facilities of the hydroelectric power plant. XPCL carried out these studies addressing questions related to fish species, biomass and fish swimming abilities.

The design comprises:

Downstream migration: Dedicated facilities with minimum flow requirements to provide constant, all year-round downstream migration for egg, larvae and fish. Provision of a complex system of entrances, channels and a hydraulically modeled exit chute. To ensure flexible operation a series of gates and a dedicated pumpstation are provided to minimize losses in energy production during the low flow season.

Upstream migration: Optimisation of the complete system including a large fish ladder to consider the specific swimming abilities of a wide range of migrating Mekong fish species. The system was adapted in an early phase to provide the right flow velocities for fish to migrate upstream and resulted in a hybrid system where a fish ladder is combined with two vertical fish locks.

The dimensions are designed such to provide sufficient capacity for the expected biomass and to be large enough to allow the largest fish like the Mekong Giant Catfish to pass.

The operation of the permanent Fish Passing Facilities commenced in late 2019. This presentation gives an overview of the design philosophy, first results and the special challenges to provide fish passage for a wide variety and number of species in a large tropical river like the Mekong.