Impact of large human constructions on a karst river hydrology: Case of the Cetina river (Dinaric karst)

Abstract

The paper studies drastic hydrological changes caused by construction of five reservoirs and six hydro-electric power plants (HEPP), built mostly in the 1960s, along the watercourse of the karst river Cetina, located in deep and well-developed Dinaric karst. The total river length from its spring to mouth in the Adriatic Sea is about 105 km. Discharges are monitored at nine gauging stations and then compared using statistical methods. Discharges measured before construction of hydraulic structures were compared with discharges measured afterwards. Analysis of the results determined that the complex natural hydrologic regime has been completely destroyed. The hydrology of the upper river, from the spring to the Prančevići Dam (length of about 65 km), is changed by the development and operation of the Peruča Reservoir and the Peruča HEPP, as well as the Lipa and the Buško Blato Reservoirs and Buško Blato and Orlovac HEPPs. Water diversion from the Prančevići Reservoir through two tunnels and pipelines to power the Zakučac HEPP has dangerously altered hydrological regime of the Cetina River’s 40 km-long downstream section. In the 65 km-long upstream section, instantaneously after the Peruča Reservoir putting in operation. In the downstream section the majority of natural flow is lost. The mean annual discharges dropped from more than 100 m3 s-1 to less than 10 m3 s-1. Due to HEPPs operation, minimum annual discharges have drastically and dangerously decreased.