The determination of countercurrent process of water surface level decrease before the thin-plate V-notch weirs

This diploma thesis deals with finding the minimal countercurrent distance of the water surface sensors used in practice for use with a V-notch weir. The thesis complements the previously obtained results of measurements in the longitudinal vertical plane of symmetry of the inlet channel with measurements on the whole countercurrently located plane of the inlet channel. The measurements are obtained experimentally in the water management research laboratory at the Department of the Water Structures Faculty of Civil Engineering in Brno. Measurements on each individual weir with top angle cutouts of 90°, 53°8´ and 28°4´ are taken at five possible positions of the sensor towards the plane of the measuring weir. All measurements are also repeated for three different vertical distances between the lowest level of the spillway edge and the bottom of the inlet channel. The obtained data are evaluated and subsequently the minimal distances for the location of the water surface sensor in front of a counter weir is determined. The thesis also includes recommendations for practical application presented in the form of text, tables and also graphically