Establishment of a freely accessible GIS database containing the results of groundwater tracing and possibilities of its use

Abstract

Tracing with artificial tracers is a research method that gives very good results in examining the direction and characteristics of groundwater flow in karst aquifers. The first mention of such experiments in Slovenian karst dates back to history and the beginnings of their use in the water resources management process in the first years of the 20th century. From that point on, more than two hundred tracer tests were carried out in Slovenian karst. Unfortunately, their results often remain hidden in internal reports in the archives of implementing organisations and are very difficult to access. The search for published results is also a time-consuming process, despite the possibilities of the use of search engines and key words. Due to the need for a systematic and rapidly accessible digital inventory of the tracer tests results, such inventory was designed and is now freely accessible in the Environmental Atlas (Atlas okolja), the spatial information system of Slovenian Environment Agency. In the database the results of 231 available tracer tests have been assembled, arranged and georeferenced. The article describes the data set concept, the process of collecting, verifying and evaluating data and the method of their transformation into a GIS database. Two points layers (injection site and sampling site) and one line layer (linear connection between both sites) were created. Symbology of line layer varies with different type of connection between injection and sampling site. By clicking on an individual element, selected data on the tracer test are displayed, and most of them are also accompanied by a copy of the data source (articles, reports). In this way it is possible to obtain more detailed information about the tracer test and its results. The database also provides a possibility of various comparative analyses. The article shows results of some of the basic statistical analyses in which the purpose and implementation of tracer tests, used tracers, characteristics of injection and sampling sites, and characteristics and velocities of groundwater flow connections were compared. It also provides an overview of the results of the tracer tests carried out within individual groundwater bodies. On the basis of the status identified, the locations for new tracer tests are proposed.