Hydrodynamically and ecologically-driven design of weirs, hydropower plants and fish passes

Historically, weirs were used to control the water level of rivers to facilitate navigation, permit extraction, prevent sea water intrusion or to power watermills. In lowland British rivers, weirs and the reaches upstream and downstream of them now provide significant niche habitats in environs that would otherwise display minimal downstream and cross-stream variations in velocities, depths and substrate characteristics. In recent years, there has been a reawakening of interest in exploiting weirs as a green energy source, either by building new structures or retrofitting existing ones with turbines. However, little is known regarding the optimum weir planform angle or crest slope nor the optimum hydropower plant dimensions for given river characteristics. Concurrently, the core environmental objectives established by the EU water framework directive mean that in-channel developments, including hydropower schemes, must demonstrate no negative impact on the longitudinal migration of aquatic species. Knowledge is also lacking regarding the impact of fish passes on mean and turbulent flow characteristics, and in turn whether these flow characteristics may be modified to increase the likelihood of an approaching animal successfully locating a fish passageway. This project will address these knowledge gaps through combined laboratory flow measurements, CFD and agent-based modelling of individual fish.