5. discussion

5. Discussion

5.1. Groundwater quality

The discussion deals with data out of the MW2 questionnaires which are presented in this report. It is important to bear in mind that not all of the 17 countries returned the questionnaire or answered it completely (e.g. no questionnaires returned from Belgium and Luxembourg) and that the answers were differently detailed.

The monitoring of groundwater quality has been undertaken in most European countries since the seventies and eighties. Only France has installed a groundwater quality monitoring system since 1902. The majority of monitoring programmes are co-ordinated by a single national institution which mostly collaborates with regional or provincial organisations. The number of collaborating organisations varies from 1 (e.g. Denmark) to 103 (Italy) and often corresponds with the number of provinces (e.g. Austria) or counties (e.g. Sweden). The responsible organisations work in the fields of programme co-ordination and reporting and, with few exceptions, local sampling and database management. Collaborating organisations have their main tasks in the fields of programme co-ordination, local sampling, chemical analyses and database management.

Six countries undertake their monitoring networks in assessment of compliance with national legislation and/or EC legislation (e.g. Nitrate Directive 91/676/EEC, Drinking Water Directive 80/778/EEC).

Groundwater quality monitoring networks are developed as a result due to national demands and (hydro-)geological situation. Evidently the monitoring objectives, which fit for each country, vary a lot from country to country. Although „general surveillance purpose" and „water quality trend identification" are widespread goals in all over the EEA area. There are many more national differences comparing the other purposes. The Netherlands e.g. have great problems with agricultural soil overuse that endangers their shallow groundwater aquifers with e.g. fertilisers. Consequently their national network takes care to this special situation. Whereas in the north of Denmark e.g. a special monitoring network (with only four sampling sites) was installed to control the impacts of airborne pollutants due to the serious acidification there. In other countries like Portugal, Spain or UK seawater intrusion in coastal areas is also investigated within their monitoring networks. It can be stated, that the knowledge of the different national monitoring objectives and consequently of the criteria for the sampling site distribution is essential for any further evaluation and comparison of the network data.

All networks described in the questionnaires have national extent with the exception of the networks of the German Länder which are regional. Within the different types of groundwater resources (in porous media, in karst, in others like till, silt, volcanic aquifers...) the majority of sampling sites are distributed evenly within the whole groundwater area. Furthermore many are concentrated around drinking water wells. Only in Germany and Portugal sampling sites also investigate impact areas. As a matter of fact records from the first sampling site group cannot be compared with records from the ones in impact areas. The national networks comprise distinct areas and distinct number of sampling sites and as a consequence a broad heterogeneity of sampling site density can be found. The following examples for groundwater in porous media may underline this with fact:

The greatest area investigated is in Spain and comprises 79,258 km², the smallest area with 30 km² in Finland. A comparison of their sampling site density per square kilometres shows that in Finland the density is about 0.57 and in Spain about 0.014 sites/km². Density ranges within all networks from 0.003 up to 0.57 sites/km²; or the number of sampling sites varies from 1,162 (France) to 4 (Norway; special programme). The situation in karst and other groundwater resources is also very heterogeneous. The differences arise from the differing national objectives and (hydro-)geological situations and land use.

Investigated determinands vary between the monitoring systems. They are adapted to the national circumstances but cannot really be compared on a European level at this stage of time. The total number of investigated parameters varies from 15 to 106, even the number of parameters measured for basic programmes ranges between 14 and 51. The parameters observed can be divided into 5 groups, the descriptive parameters (e.g. pH, conductivity, temperature,...) and the major ions (e.g. Ca, Mg, Na, K, NO₃, NO₂, NH₄, Cl, SO₄, HCO₃,...), which are the most investigated parameter groups, then followed by heavy metals (Pb, Cd, Ni, Hg,...), pesticides (herbicides, insecticides) and chlorinated solvents (trichlorethene,...). The variety among the countries concerning pesticides and chlorinated solvents are surprisingly high, e.g. 1-64 pesticides are observed. Sampling frequency also differs a lot, e.g. from 0.5 to 12 times/year for basic programme parameters.

Sampling and analysing procedures are key elements of every monitoring programme, evidently it is necessary that regulations for sampling and analysing procedures provide a standard to make the data obtained comparable. This fact become more important if an EEA network will be installed. Sampling and analysing is carried out from 1 up to more than 200 institutions which are mostly public ones. Not every variable of a single sample is analysed by a single institution. The majority of countries have standardised sampling and analytical methods as well as standardised regulations for precision and accuracy, but on their national level.

Data are stored and managed in various national databases. The databases used are e.g. ORACLE, VAX/Rdb, INGRES and INFORMIX. Frequent used operating systems are for example VMS, UNIX, WINDOWS, DOS and MVS on hardware such as Digital, HP, IBM, SUN, etc. The languages mostly used are e.g. FORTRAN, PASCAL, C and COBOL. Data are available on paper sheets, floppy disks and reports and internet (e.g. Austria). Most countries release data free of charge and without restrictions. To make data more and exchangeable it will be a need to design an interface for data exchange and provide codification guidelines. With this measures a EEA wide database can be installed.

Sampling site details held at source were available from nearly all of the countries. All countries have information about the local number of sampling sites, nearly all provide information about location, altitude of station, period of record, measured variables and (hydro-)geological information. Only few information about use of water or possible impacts is available.

5.2. Groundwater Quantity

This report contains data provided via the MW2 questionnaires. Under the consideration that not all of the countries returned answered questionnaires and that the answers given were differently detailed, this discussion is restricted to the information supplied.

The monitoring of groundwater quantity has a long tradition in Europe. The eldest groundwater monitoring network have been in operation since 1845, most of them have been installed at the beginning of the 20 century. The average length of records lies between 20-35 years. The majority of monitoring networks is managed by one single national institution, except the networks of France and the German Länder, which have a regional scale. The national organisations work all in the fields of programme co-ordination, furthermore many of them are responsible for local sampling, database management and reporting. Often they are supported in these tasks by collaborating organisations like water supply companies (UK) or water management offices (Germany). The number of collaborating organisations often depends on the number of provinces or the regional administrative borders in a country.

The respondents gave broadly similar objectives for groundwater monitoring activities such as the collection of basic groundwater data, the management of groundwater resources and the water supply, the support for (hydro-)geological science like the reasons for temporal and spatial changes of the groundwater level. The monitoring objectives often correspond to special national requests. For example: In the Netherlands there are shallow groundwater resources, if their level sinks, households, agriculture and industry can be endangered. Consequently good supervision of monitoring levels is necessary. In Portugal and UK the groundwater is endangered by seawater intrusion, thereupon the groundwater quantity monitoring network is also adapted to this special problem.

The connection between monitoring activities and legal obligations is surprisingly low. Only seven countries monitor groundwater in assessment of national legislation and only Portugal monitor due to EC legislation. In opposite to groundwater quality problems there is no current EC Directive which mentions specific requirements for groundwater quantity monitoring. This may be an important aspect for the future installation of the EEA wide groundwater monitoring network.

In most cases the extent of monitoring networks is national, with exception of the German Länder and French Regions. The majority of groundwater observation points is distributed evenly within the different types of groundwater resources such as porous media, karst, artesian and deep groundwater, etc. The total number of sampling sites, the total area and as a consequence the sampling site density per km² varies a lot. These differences are often a result of heterogeneous national as well as (hydro-)geological situation. To give some examples; for porous media: The largest area investigated is in Spain with 79,258 km², the smallest is in Thüringen/Germany with 900 km². The highest number of sampling sites can be found in North-Rhine-Westfalia/Germany with 42,900 sites, the lowest in Ireland with two selected sites. Density of sampling sites varies from 0.004 in Norway up to 7.3 sites in Finland. The comparison of the other types of groundwater resources shows equal results.

The networks comprise various types of observation points such as bored and dug wells, which are mainly used and then driven wells and spring wells. The variables observed are broadly the same; groundwater level (all countries), then groundwater temperature (nearly all) and furthermore spring level and spring discharge. Quite all countries have observation sites which observe water level in a recording way. The frequency of other observation points is distinct, for example: for groundwater level it varies between weekly to 2 times a year, for groundwater temperature it differs from every 15 minutes to 2 times a month. A solution for a better correspondence of sampling frequency should be found before the EEA wide network starts to operate. It is encouraging that nearly all stations indicate altitude and co-ordinates. The quality of observation and sampling methodology is determined by various national standardised procedures. Quality assurance procedures are key elements within every monitoring network, they help to make data obtained more reliable and comparable. It is made e.g. by regular controlling of stations (e.g. Austria), plausibility checks (e.g. Netherlands, Germany), visual examination or general supervision of project managers (e.g. Spain). A harmonisation of these procedures will also be necessary for the EEA wide network.

Data management and storage is made via distinct national databases. Widespread databases are e.g. ORACLE, INGRES, RDBMS, etc. The most frequent operating system used are for example UNIX, VAX/VMS, DOS, Fortran, etc. Hardware equipment comprises e.g. HP, Digital, Bull, Sun, etc. and languages as well as software tools often installed are Fortran, Pascal, Cobol, C++, Windows, SQL, SAS, etc. To facilitate data access and data transfer it will be a need to design an interface and to provide codification guidelines. In most cases data are no subject of restriction and they are accessible without paying a fee. They can be made available on paper sheets, reports and floppy disks. Two countries, Norway and Sweden also make their groundwater data available via internet.

Observation site details held at source contain many information throughout all member countries. Information about location, name, altitude and number of station, name of groundwater region, period of record, frequency etc. are given.