The International Hydrogeological Map of Europe, scale 1:1,500,000 (IHME1500) is a series of general hydrogeological maps comprising 25 map sheets, partly with explanatory notes, covering nearly the whole European continent and parts of the Near East. The national contributions to this map series were compiled by hydrogeologists and national experts in related sciences under the auspices of the International Association of Hydrogeologists (IAH). The project is supported by the Commission for the Geological Map of the World (CGMW). The scientific editorial work is financially supported by the Government of the Federal Republic of Germany through the Federal Institute for Geosciences and Natural Resources (BGR) and by the United Nations Educational, Scientific and Cultural Organization (UNESCO). BGR and UNESCO have been responsible for the cartography, printing, and publication of the map sheets and explanatory notes. The IHME1500 seeks to represent the hydrogeological setting of Europe as a whole, without regard to political boundaries. The map can be used for scientific purposes, for large-scale regional planning and as a basis for detailed hydrogeological mapping. The preparatory phase of this project began in 1960 during the XXI International Geological Congress in Copenhagen, when the IAH Commission on Hydrogeological Maps was appointed to prepare a small-scale European Hydrogeological Map project. With the assistance of UNESCO an International Legend for Hydrogeological Maps was issued. Based on these activities the General Legend for the International Hydrogeological Map of Europe (1974) and the first IHME map sheet C5 Bern (printed in 1970) were compiled. The compilation of the IHME1500 was based on the International Geological Map of Europe 1:1,500,000 (IGK1500) applying the same scale, topography and projection. Moreover, the delineation and lithological attribution of the aquifers was partly derived from the geological information mapped in the IGK1500. Initial attempts to include quantitative data in the map as e.g. specific capacity, well yield, transmissivity and groundwater recharge resulted in the recognition of a wide range of data heterogeneity, which is not compatible with the target of a uniform map representation. Thus, such information are not reproduced all-encompassing in the IHME1500 map sheets, but selected topics are depicted regionally depending on their significance for hydrogeological descriptions. The small scale of the map allows the representation of only a limited amount of hydrogeological information. In order to provide additional information e.g. on climate, chemical composition of groundwater and any geological features of significance to groundwater flow, explanatory notes have been published for 18 map sheets. The publication of the printed IHME1500 map sheets was completed in August, 2013. Both, the printed maps and the raster files of the scanned map sheets are entitled as ‘IHME1500 print’. Additionally, several topics of the IHME1500 have been digitised resulting in two spatial vector datasets in a shapefile format for the purpose of visualisation and data processing using Geographic Information Systems (GIS). Envisaged enhancements, such as the completion of currently lacking parts from the North Cape to Northern Ural, updates of map contents and the addition of attributes will be exclusively added to the vector data. Therefore, the spatial vector datasets of the IHME1500 are assigned a version. ‘IHME1500 v1.1’ is the current version. ‘IHME1500 v1.1.1’ comprising the map sheets D1 Nordkapp, E1 Kanin and F1 Vorkuta is under preparation. The BGR Geoviewer provides a web map service (WMS) of the IHME1500, which includes a draft of the new map sheets D1, E1 and F1. Source.