HOVER – Guidelines and review reports

Many guidelines and documents are defining the technical steps needed for the elaboration of maps and web tools. They are described elsewhere in the web page. Not all documents are described here for simplification measures but can be found in the repository deposit (https://egdi.geology.cz/).

The construction of the vulnerability maps needed a preliminary task consisting in the comparison of the internationally commonly applied index methodologies for assessing the vulnerability of the upper aquifer to pollution. The report (https://repository.europe-geology.eu/egdidocs/hover/hover%2Bd7_1_report_final.pdf) portrays existing methods assessing the groundwater vulnerability to pollution and proposes a methodology to enable vulnerability maps at the pan-European and regional transboundary scale.

Groundwater occurrence data on emerging organic compound in groundwater in the peer reviewed and grey (not published data) literature for Europe has been formally reviewed. A total of 39 published studies and questionnaires completed by 30 European institutes allowed the comprehensive compilation of data in Europe. The aims of this review was to; understand the current state of groundwater sampling of EOC’s in Europe and the developments in recent years, understand the different methods for sampling and analysing EOC’s in Europe, and highlight ongoing research and further areas for research necessary to develop a picture of EOC’s in Europe (https://repository.europe-geology.eu/egdidocs/hover/hover%2Bd8-1a_final.pdf and https://repository.europe-geology.eu/egdidocs/hover/hover%2Bd81bunpublished.pdf).    

A guideline for the application of groundwater age distributions for design and assessment of monitoring programs and trend assessment in line with thewater framework directive was developed.  This work shows that up to now, the use of the dating tools is mainly carried by researchers, for areas of limited extension. A trial to set up a flow chart explaining in which context the use of dating tools could be of interest is made (https://repository.europe-geology.eu/egdidocs/hover/hover_d63_v1.pdf).

In addition, a detailed study on the Investigation of age distributions in water supply wells and recommendations for application of tracers and models mainly for estimating groundwater ages between 100 and 1000 years aimed at proposing the use of multiple tracers including 39Ar for assessing age distribution of well fields and pumping wells. (https://repository.europe-geology.eu/egdidocs/hover/hover_d64+age+distributions+final.pdf).

This work was complemented by a proposal for building a Database of groundwater age indicators and age distributions for vulnerability classification and sustainability assessments.

In order to give a homogeneous approach for the estimation of the natural background Level (NBL), it was first proposed a pan-European approach for elaborating a litho-geological classification system based on the capacities of rocks to release elements to groundwater.  The proposed method combining the BRIDGE-HOVER Lithology water families was validated using additional dataset and used for the second step of the study (https://repository.europe-geology.eu/egdidocs/hover/hover+d3_2_report_2019_06_28.pdf). For each selected elements (SO4, As, Cd, Cr, Cu, Ni, Zn and F) from 7 countries, average values were calculated for each selected water point and linked to a BRIDGE-HOVER lithology and geographical area. By statistical data treatment based on pressures and lithologies, it was possible to define sets of homogeneous lithologies. For each of these sets, the 90th percentiles were calculated to estimate the maximum possible natural concentrations (NBL). This work constitutes an important contribution to the definition of NBLs (https://repository.europe-geology.eu/egdidocs/hover/hover_33_statistical_data_treatment_backgroundlev.pdf).