Water losses from the Ričice reservoir built in the Dinaric karst

The Ričice reservoir was built in 1987 in the central part of the bare Dinaric karst region in Croatia, on the border with Bosnia and Herzegovina. The reservoir water level rise rapidly after rainfall, but due to high water-loss rates the water remains impounded for a very short time. The reservoir volume at the spillway altitude is 18.4 × 106 m3. Due to water losses, the mean annual water volume in the 1989-1995 period was 6.5 × 106 m3. Interdisciplinary analyses and investigations of geological, hydrological and hydrogeological factors which caused water losses from the Ričice reservoir have been carried out. Water losses from the reservoir are defined using a water budget equation. An assessment of the calculation of hydraulic conductivity, and a definition of the groundwater level below the Ričice reservoir, using Darcy's equation for vertical flow, is carried out. It may be concluded that the water losses from the Ričice reservoir are mainly controlled by the water level in the reservoir.