Karst spring catchment: an example from Dinaric karst

Abstract

Definition of karst spring catchment or basin area and boundaries belongs to one of the greatest prob- lems of karst hydrology and hydrogeology, not adequately solved until now. This paper tries to address main problems in defining this crucial parameter. The theoretical aspect of this issue is discussed in the first two chapters. We have presented the example of the catchment area and bound- aries definition for the karst spring Zrnovnica catchment in Dinaric karst. Topographic catchment area of the Zrnov- nica Spring is 8.4 km 2 . The significant discrepancy in size of the hydrological-hydrogeological and topographical catchment is very common characteristic for the springs located in the karst areas. In the case of the Zrnovnica Spring, the hydrogeological catchment is at least seven times larger than topographic. Two following simple hydrological methods are used in order to calculate its hydrologic-hydrogeologic catchment: (1) the relationship between mean annual discharges and annual rainfall falling on the catchment, and (2) the Turc method. It is estimated that hydrogeologic catchment area of the Zrnovnica karst spring is much larger and very probably ranges between 60 and 80 km 2 . These values represent first rough assessment, which should be confirmed by more detailed interdisci- plinary investigations. According to the performed tracing tests, it seems that the catchment spreads on the north-east from the topographic catchment and that the Zrnovnica Spring karst aquifer is fed by groundwater overflow from the neighbouring more abundant karts spring Jadro.