engleski

Water Resources of the Velebit Nature Park

It is well known that water balance of one area means mutual relationship between rainfall quantity, sum of runoff quantities (surface and subsurface runoff) and evapotranspiration quantity during specific time. Usually, catchment area is what we use for our analysis. In the case of Nature Park Velebit that is not possible because terrain comprises of many catchment areas (boundaries are defined in 1981) and covers area of Lika region, Podvelebit region and part of Zrmanja catchment area. Aditional complexity arises because of fact that the park area is one extremely karstic area with significant topographic and climatic distinctions. Particularly, due to elevation in parts of the Park with higher altitude, surface runoff is increasing and sinking is decreasing. Also, evapotranspiration is decreasing due to lower air temperatures at higher altitudes. In addition, climatic characteristics inside the Park are changing from mediterranean to continental-mountainous. Nature Park Velebit covers area of 2247 km2 and encompasses almost all Velebit – the most significant Croatian mountain based to its relief, geology, hydrogeology, hydrology, speleology and vegetation. Although entire Velebit presents exceptional nature resource value, two areas inside its territory are especially highlighted because of their characteristics. Those are National Park « ; North Velebit» ; and National Park « ; Paklenica» ; . Nature Park Velebit area is one of the areas in Croatia with highest rainfall quantity. However, owing to litological structure and complex tectonical relationships, there is still shortage of large perennial streams. The fact is that waters originating in the north-northwest side of Velebit often sink after short surface flow and then discharge in the Adriatic Sea. Precipitation waters from west-southwest sides of Velebit become torrential intermittent streams which are quickly draining into Adriatic Sea. Smaller part of those waters is infiltrating into karstic underground and like waters from the north and north-east side of Velebit, are becoming coastal springs and/or vruljas, or discharge difusely into sea. It's estimated that 2.5 billion m3 of water from area of Nature Park Velebit discharge uncontrollable into the sea. Those are huge quantities of water which are unfortunately seasonaly very unevenly distributed, but they can also have great importance for water management of Croatia.

water balance; catchment areas; water discharge

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