engleski

Drastic hydrological changes caused by hydroelectrical development in karst: a case of the karst river Zrmanja (Croatia)

The paper analysed changes in the hydrological regime along the karst river Zrmanja (the Dinaric karst of Croatia) caused by operation of the reversible or pumped-storage hydroelectric power plant Velebit (RHEPP Velebit), which started with operation in 1985. The total river length from the spring to the mouth in the Adriatic Sea is 70 km. Discharges along the whole river course are monitored at nine hydrological gauging stations. For all nine analysed stations the decrease of the mean annual discharges started from 1985 has proven to be statistically significant. However, it should be stressed that the Zrmanja River natural regime is extremely complex due to a deep, well developed and generally undiscovered subsurface karst morphology and its influence on regional surface and groundwater circulation. The influence of RHEPP Velebit operation on the maximum annual discharges is not statistically significant. Statistically significant decrease on the minimum annual discharges is observed at only one gauging station located at the Zrmanja River downstream of the Razovac Reservoir. At the same time climatological changes have been monitored in the analysed area. It has been established that there has been an annual increase in air temperature since 1988 and an annual decrease in rainfall since 1983. A general conclusion is that the decrease in the mean annual discharges along the Zrmanja River is mainly caused by the RHEPP Velebit operation and only in a smaller degree by climatological changes. On the basis of the available data it was not possible to separate precisely the influences of these two factors.

Karst river • Karst hydrology • Engineering hydrology • Hydroelectrical development • Dinaric karst • the Zrmanja River (Croatia)

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