Environmental Integration of Small Hydropower Development

On the basis of cooperative research with European professionals, problems relating to environmental and ecological protection were discussed while small hydropower development in China currently was introduced in this paper. Guidelines of small hydropower development dealing with environmental protection were sug- gested hereby. Various specific technical environmental solutions focusing on small hydropower development applied in European and other developed countries were also introduced in this paper. Main environmental solutions are discussed as follows： integrated design should be advocated during plan/design stage,＂ ecohydraulic engineering and its utilization in SHP design and construction; effective technical approaches to relieve and eliminate the impact of river interception and fix the reasonable minimum biological flow; environment-friendly mitigation and compensation measures for high/low-head hydropower schemes applied in diversion works, intake, nature-like fish-passes, penstock and powerhouse design; study and application of the new technology, material and equipments; launching renovation of environmental protection in existing stations; emphasiz- ing public participation and their acceptability for the SHP environment; coordinated inter-disciplinary study at national level, etc. Two case studies in Sweden and Australia are given here.

Innovative configuration of vertical slot fishway to enhance fish swimming conditions

A vertical slot fishway(VSF)is among the most effective and commonly used fishway structures to enable fish to pass through artificial barriers such as dams and weirs in the river.Nevertheless,such structures need further improvements in providing better swimming conditions for fish inside the pool and enhancing attraction at the entrance.Therefore,the main objective of this study was to investigate the influence of slope and whether integrating some cylinder structures inside the fishway could enhance further attraction and provide better swimming conditions for fish.This study consists of several numerical simulations,first considering the fishway without cylinder elements while testing three different slopes under two different discharges.Then,the same numerical simulations were conducted,considering cylinder elements of different diameters and arrangements inside the fishway.The numerical model was validated by comparing computed velocities with those measured experimentally from the literature.The results show that the maximum velocity and turbulent kinetic energy(TKE)in the main jet increase as the discharge increases on the same slope.The flow velocity and TKE decrease in the areas inside the pool and between the two baffles.Introducing cylinder elements inside the fishway reduces the principal flow’s maximum velocity.Also,inside the pool,low-velocity regions were expanding.A comparison between the design with a cylinder and the simple VSF indicates that the presence of a cylinder reduced the maximum velocities for the smallest and highest slopes by 6.21%and 9.86%on average,respectively.However,in terms of TKE,cylinders inside the fishway could provide better performance than simple VSF,mainly for low-flow conditions.Finally,this study’s solution-oriented findings provide insights that could help design cost-effective fishways by improving particularly fish attraction to the fishway.