2.13.1. Characteristics of Groundwater
In Portugal the main aquifer systems are in porous media and karst. The area of porous media has an extension of 26,000 km² (i.e. 29.4 % of national territory), karst groundwater comprises an area of 5,500 km² (i.e. 6.2 %). The aquifers systems are located in meridianal and occidental Mesocenozoic border and tiercearies basins of Tejo and Sado. The average productivity is between 10 and 30 l/s per well. Almost 40 % of these aquifers have a productivity of more than 30 l/s. In general the unconfined aquifers have a higher or moderate vulnerability. Some other aquifers are located in residual soils of ancient rocks, e.g. igneous or metamorphic formations, which are important local resources. The productivity of these aquifers is less than 3 l/s and is related to the periodicity of wet and dry periods. As the groundwater quality is mainly good about 70 % of the water supply is supported by groundwater resources. The potential water resources are composed of 81,890 mio. m³/year precipitation and 35,100 mio. m³/year inflow from neighbouring countries. The yearly evapo-transpiration rate is 44,560 mio. m³ high. Most of the water is used in the agricultural sector (293 mio. m³/year), followed by households (276 mio. m³/year) and finally industry (145 mio.m³/year).
2.13.2. Structure of the Administrative Organisations Concerning Groundwater Quality
Head of all groundwater monitoring activities is the Portuguese Ministry for the Environment. On behalf of the Ministry INAG (Instituto da Agua) co-operates with several DRARNs (Direccoes Regionais do Ambiente e Recursos Naturais) in fields of groundwater monitoring. In some cases quality monitoring is also done by so called ARSs (Administracao Regional de Saude). At present groundwater is only monitored in the Miopliocenic systems of Tejo and Sado. These regional networks are done by the DRARN of Lisbon and Tejo Valley. It was established in 1977 with 28 observation points which control the seawater intrusion at the estuary border. In 1985 these networks were increased; 46 new observation points were installed to get an average situation of the groundwater region.
Since 1983 in the Algarve region within karst and porous media regional networks have been operating in order to get information on seawater intrusion points and agricultural nitrate pollution areas. At the beginning there were 25 bored wells and 3 dug ones. Samples were taken 2 times a year. From 1992 to 1993 an implementation of nitrate monitoring with 60 sampling sites was made there. At present the DRARN Algarve implements a quality network with 30 sampling sites located in areas for water supply.
INAG and some institutions are developing a protocol to do several projects in order to optimise the current quality networks, to implement others to support the water resource management and to comply the national and international laws.
2.13.3. Monitoring of Groundwater Quality
The Rede de Control da Qualidade" is a regional groundwater monitoring network in the Tejo and Sado Miopliocenic aquifer systems that informs about seawater intrusion and nitrates contamination and provides data about the present groundwater status. The Instituto da Agua-INAG co-ordinates the network activities and runs the database. The DRARNs take the local samples and co-operate with INAG in report writing and database management. The 74 sampling sites are located evenly in the whole area as well as concentrated around specific sites such as impact areas or drinking water wells. Samples are taken from 1 to 4 times a year. The analyses are done in a public laboratory. Sampling procedures are standardised. Analyses have to be carried out with regard to laboratory quality assurance standards but detailed information was not available at this stage of report. The earliest record was taken in 1977, it has an average length of 18 years. Raw data are stored in an ACCESS, ORACLE-RDBMS database, the operating systems are DOS, OSF1, using ALPHA DIGITAL and PCs as hardware. Software tools are SQL, ACCESS BASIC, C, SQL+ Forms and Reportwriter. The data are available on floppy disks and reports. Reports are published by INAG. To date there are no periodical Portuguese reports concerning groundwater quality observations, because the monitoring network is only just starting in some regions.
2.13.4. Structure of the Administrative Organisations Concerning Groundwater Quantity
Groundwater quantity monitoring is undertaken in all relevant aquifers of the occidental and meridianal Mesocenozoic borders, in the Tejo and Sado system aquifers and in the karst of Palaeozoic formations. INAG co-operates with several DRARNs (Direccoes Regionais do Ambiente e Recursos Naturais) in fields of quantity monitoring activities. The operation of local networks is done by water supply systems. INAG and DRARNs act on behalf of the Ministry of Environment. INAG and some institutions are developing a protocol to do several projects in order to optimise the current quality networks, to implement others to support the water resources management and to comply the national and international laws.
2.13.5. Monitoring of Groundwater Quantity
Groundwater quantity monitoring has several purposes; it helps to characterise the groundwater, it is the basis for analysing the space/time development of the piezometric level in terms of natural recharge, soil occupation and water uses and it is necessary for the groundwater management. The responsible organisations are INAG and the DRARNs. INAG co-ordinates the whole programme and with the help of the DRARNS it manages the data and reports on groundwater quantity. In return the DRARNs are involved in local sampling. The network operates on national level, the main aquifers in Portugal are covered. About 477 sampling sites observe groundwater in porous media and 143 sampling sites do the same in karst media. 430 are bored wells, 168 dug wells and 31 spring wells which provide water level and discharge data. The sampling frequency varies from 12 to 2/3 times a year. The piezometric level is measured by electric sound of contact. If a registered value does not seem realistic it will be confirmed at the field. If a critical situation occurs an alert (of decisiveness) will be activated. The network has been in operation since 1970. The average length of a record is 15 years. Data are stored in an ACCESS, ORACLE-RDBMS database, the operating systems are DOS, OSF1, using ALPHA DIGITAl and PCs as hardware. Software tools are SQL, ACCESS BASIC, C, SQL+, Forms and Reportwriter. The data are available on floppy disks and reports at INAG. Monthly hydrological bulletins are published by INAG. In the reports the development of groundwater piezometric level is laid down. Some other reports have been done by the Universities and by the national Laboratory of Civil Engineering.
For references, please go to http://www.eea.europa.eu/publications/92-9167-032-4/page015.html or scan the QR code.
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