Surface water and groundwater are closely interconnected. Understanding their interaction is crucial for the management and protection of both natural resources. In Slovenia, many drinking water supply systems are directly dependent on the groundwater which recharges from surface water. Therefore its quality and quantity are related to the state of the surface water.
To study this relationship, an aquifer near Črneče near Dravograd was selected, where a fair amount of quality data is available. The area comprises a river terrace, a river plain with Drava River to the north and a stream in the Črneški Graben to the west. The bedrock consists of poorly permeable metamorphic rocks with highly permeable alluvial deposits deposited over it.
In the numerical hydrogeological model the water level data of the Drava River, the flow data from the stream and the groundwater level data from four observation boreholes was used. The model covers the area of 330 m x 330 m and consists of two layers. During calibration, five zones with a permeability coefficient between 1.10 x 10 3 m/s and 9.50 x 10 3 m/s have been determined, together with a zone representing the non permeable area of the landfill.
The results of the model simulations with various hydrological and hydrogeological conditions show the dependence of the groundwater on the water levels of the surface water, as well as on the amount of water from recharge area. At medium groundwater levels, the flow direction is south north recharging the Drava River. When the water level in Drava River is raised, the flow changes directions to southwest-north-southeast. With the rise of water in the stream, the flow direction is from west to east. Lowering the amount of water from the recharge area causes the reversal of the flow direction from south-north to north-south. In other scenarios only the slope of the groundwater flow was changed.
The model enables further research of the dynamics of the groundwater and the transport of the substance in the groundwater in the Črneče area near Dravograd.