engleski

Hydrologic Characteristics of Dinaric Karst

Dinaric karst covers about 60.000 km2. It stretches the lengths of the eastern coast of the Adriatic Sea, from the Bay of Trieste in the north to the Drim River basin in the south, and the Western Morava valley in the east. This karst structure is some 600 km in length and up to 200 km in width, falling within the borders of the following seven states: Italy, Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Montenegro and Albania. The Dinaric karst region is an area of dramatic variety of karst surface and underground forms, karst water phenomena, species, habitats and peoples. Hydrology is a scientific discipline within the earth sciences. It concerns the occurrence, movement and composition of water below and on the earth’s surface. Hydrology is based on water budget concept. In karst hydrological investigations, the basic problem is that subsurface water is highly heterogeneous in terms of location of conduits, location of vertically moving water toward the phreatic zone, and flow velocities. Due to this reason hydrological and hydrogeological methods and approaches should be closely connected in karst investigations. The determination of the catchment boundaries and the catchment area is the starting point in all hydrological analyses. For water circulation in karst, this classical and relatively simple hydrological problem, in more homogenous types of terrain, represents extremely complex, sometimes unsolvable task. The differences between the topographic and hydrologic catchments in karst terrain are so large that data about the topographic catchment are useless. Generally the position of the karst catchment boundaries depends upon the groundwater levels which strongly and sharply change in time. In some situations very high groundwater levels causes the redistribution of the catchment areas, i.e. overflow from one to other catchment. Specific characteristics of karat floods due to strong groundwater rising, and limited swallow capacity of the ponors will be explained. One of the almost unavoidable characteristics of karst open streams, creeks and rivers is that they either have partial water loss along their course or completely sink into the underground. Sinking, losing and underground streamflows are more typical, significant and relatively frequent karst phenomena in Dinaric karst. Hydrological characteristics of the Lika, Gacka, Dobra and Mrežnica Rivers will be explained. Karst systems are known to change over time due to natural factors and in the recent time very fast due to anthropogenic influences. Anthropogenic intervention, especially constructions of dams and reservoirs as well as inter-basin water transfers can introduce instantaneous and distinct change in catchment areas and boundaries. Natural and anthropogenic changes in karst regions frequently cause strong, sudden and dangerous processes at the local and regional scale. The benefit resulting in one area was frequently smaller than damage caused in another area. Examples of Boljunčica Reservoir and development of hydroelectric power plant Gojak on the Dobra River are given.

hydrology; karst; Dinaric karst

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