There is an enormous untapped potential for hydropower generation in rivers with large head and high flow variation, currently not feasible for conventional hydropower dams. Conventional dams make use of the potential energy, but waste kinetic energy from spillage during periods of high flows. This article studies the possibility of harnessing energy from potential and kinetic energy from hydropower dams with large head and flow variation, analyses its potential, and shows possible technologies. Focus is given to a Moveable HydroElectric Power Plant (HEPP) system in which the turbine module can be adjusted according to the flow and water level in the river. During floods the exceeding flows can pass above and below the Moveable HEPP results in a sub-pressure environment after the turbine module, thereby reducing the dam's downstream head, increasing the pressure difference between the turbine inlet and outlet and the flow through the turbine, which increases the electricity generation of the dam. Dams with head increaser arrangement have been implemented in several dams in the 1930-1950s and now are regaining attention in Middle Europe. The main intention for its implementation is harnessing hydropower generation at run-of-river plants, with low-head, with a 20% to 30% cost reduction, lower flooded area at the dam site, the resulting evaporation and the impact on the aquatic fauna. A case study was performed with the proposal of the Aripuanã Moveable HEPP in the Madeira River with a 26 meters height dam and a generation capacity of 1,400 MW. The increase in generation with the head increaser effect is as high as 21%. The estimated potential for this technology in the Amazon region is 20 GW. Other potential locations are discussed in the article. Dams with head increaser effect have been successfully implemented and have the potential to become a major alternative for base load renewable energy in the future.

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Combining hydraulic model tests with numerical flow analysis: The design flood for the reservoir above the Ashta 1 power station in Albania Summary: This article describes hydraulic scale model tests and compares the results with those obtained from a numerical simulation of the design flood (5,900 m³/s corresponding to an estimated 500-year event) for the reservoir of the planned Ashta 1 Hydromatrix power development in Albania. The investigation led by Pöyry Energy, included a 2d analysis of this extreme event. Considering the substantial effect the calculated results will have on further planning and design as well as the importance of the flood water levels for a neighbouring residential area and a main traffic connection, a contract was awarded to the Institute of Hydraulic and Water Resources Engineering at the Vienna University of Technology for performing hydraulic scale model tests as a basis for these numerical analyses and for checking the results. This article presents the results of the two independently-conducted studies. Einleitung 1.