2. Groundwater quality presentation in basic hydrogeochemical maps at a scale of 1:50,000 by digital data treatment applied in the Slovak Republic

t: Hydrogeochemical maps have been compiled in Slovakia for more than 40 years. While till 1990 there were issued only print versions of the maps, a new generation of maps, especially since 1994, has been innovated by digital processing of hydrogeochemical information. Uniform principles for their digital imaging are based on the requirements of simplicity, clarity and reproducibility, as well as the relevant Guidelines for the compilation of basic hydrogeochemical maps released by the Ministry of Environment in 2004. The hydrogeochemical maps contain basic information on the chemical composition and quality characteristics of groundwater. The information value of the map has been divided into levels of basic information consisting of qualitative and geochemical (genesis) characteristics of the groundwater, water management criteria and a database of chemical analyses. Therefore the hydrogeochemical maps display three essential criteria, namely: quality (colour in area), geochemistry (raster in the area) and water-management (contour marks - isolines). The quality and water management criteria are derived from the relevant Slovak standards for potable and raw water and geochemical criteria reflect the particular genetic types and chemical types of groundwater. The information value of a new generation of maps is highlighted in a modern approach that is sufficiently custom-friendly to a lay user and the wider scientific community addressing issues of water management (authors)