Evaluation of the Vranov Reservoir Functions

Abstract Study area – Vranov reservoir on the river Dyje lies in the South Moravian region in the Czech Republic. A multipurpose reservoir, Vranov, is a significant hydraulic structure whose primary purpose is water retention, including managing flood conditions. The reservoir itself and its surroundings are intensively used for recreation, and a hydroelectric power station has also been built there. In 1982, the reservoir began to be used as a source of drinking water. The objective of this study is to elaborate hydrological data – daily total precipitation and daily surface runoff – from 1981 to 2019, evaluate the influence of the Vranov water work, focusing on the hydrological extremes, and evaluate individual functions of this reservoir. The results showed an increase in the number of days of hydrological drought. The influence of the dam as a flood protection element is significant – in summer 2006, a peak of flow rate value of 551 m3 s−1 was transformed to 234 m3 s−1. The reservoir itself and its catchment area have multipurpose usage. Problems may arise in connection with extreme hydrological events when the reservoir cannot perform all its functions at the same time as it does at normal water levels and runoffs. Whether in times of flood or drought, it is necessary to resort to emergency manipulation of the reservoir and choose which of the purposes of the reservoir will be primary at that time.