This paper is concerned with the determination of the relationship for the calculation of the discharge coefficient at free overflow over a rectangular sharp-edged broad-crested weir without lateral contraction. The determination was made on the basis of new measurement in a range of the relative thickness of the weir from 0.12 to 0.30 and newly in a large range of relative height of the weir extremely from 0.24 to 6.8 which greatly expands the application possibilities of low weirs. In addition, the effects of friction and surface tension on the value of the discharge coefficient were evaluated as well as the effect of the relative thickness of the weir. The new equation for discharge coefficient, expressed using the relative height of the weir, was subjected to verification made by an independent laboratory which confirmed its accuracy.
The water structures Hričov - Mikšová - Považská Bystrica are a group of channel hydro power plants (HPP) on the Váh Cascade. Modelling methods verified on other channel hydro power plants are easily applicable in their case. In 2006 were by our department provided terrain measurements and hydraulic research on these water structure systems. The results of measurements were used for the better calibration of hydro dynamical model of these power plants. The presented paper describes this process. This work was supported by Science and Technology Assistance Agency under the contract No. APVT-20-046302.