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Methodology for obtaining data
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OVERVIEW:
Water quality in rivers, lakes and groundwater is reported under WISE-SoE using a harmonised data model. All determinands (nutrients, hazardous substances and supportive determinands) are coded using a unique identifier. The representation of values below the limit of quantification is identical for disaggregated data, data aggregated by monitoring site or data aggregated by water body for all water categories (rivers, lakes, groundwater) and for all determinands.
Raw data (i.e. sample values) is reported in the DisaggregatedData table.
Annually aggregated data, by monitoring site, is reported in the AggregatedData table. This includes biological determinands that are not reported using Ecological Quality Ratio (EQR) – for example chlorophyll a.
Biological data reported as EQR values, in river or lake monitoring sites, is reported in the BiologyEQRData table. The BiologyEQRClassificationProcedure table provides information on the ecological status or ecological potential class boundaries for the EQR values.
Annually aggregated data, by water body, is reported in the AggregatedDataByWaterBody table.
The full list of determinands, and the indicative thresholds for "potentially high mean annual value" of selected nutrients (i.e. used to flag potential outliers in the quality control procedures), is available in http://cdr.eionet.europa.eu/help/WISE_SoE/wise4.
1. Coverage and reference period
The data should be derived from existing national or regional monitoring programs within each country.
Submit data collected up to the end of the previous year (e.g. in 2015, submit data collected until the end of 2014).
2. Data content
Reporting of disaggregated data (i.e. sample data) is preferred for all determinands in groundwater, rivers and lakes (except for biological EQR values, please see below).
If disaggregated data is not available for reporting, then submit annually aggregated data, by monitoring site, using the AggregatedData table (i.e. for nutrients and selected biological determinands in rivers or lakes).
Reporting of data annually aggregated by water bodies is accepted only for selected determinands in groundwater (nitrate, nitrite, ammonium and dissolved oxygen) and only in the case disaggregated data or data aggregated by monitoring site can not be provided. Use the table AggregatedDataByWaterBody to report this data.
For nitrate, concentrations should be expressed in mg{NO3}/L (milligram of nitrate per litre), both for surface water and groundwater.
For nitrite, concentrations should be expressed in mg{NO2}/L (milligram of nitrite per litre), both for surface water and groundwater.
For ammonium, concentrations should be expressed in mg{NH4}/L (milligram of ammonium per litre), both for surface water and groundwater.
If needed, the following conversion factors can be applied to convert from mg{N}/L (milligram of Nitrogen per litre) to the adequate unit:
1 mg{N}/L = 4.427 mg{NO3}/L
1 mg{N}/L = 3.2845 mg{NO2}/L
1 mg{N}/L = 1.288 mg{NH4}/L
There is no need to report both BOD7 and BOD5. BOD5 is preferred, but if BOD7 was reported in the past do not switch from BOD7 to BOD5.
Dissolved fractions of metals (copper dissolved, nickel dissolved, iron dissolved, ...) are not available as specific items in the list of determinands anymore. Instead of this, please use the codelist option "dissolved" in procedureAnalysedFraction field for specification of such determinands.
Use the BiologyEQRData table to report the annual mean value of biological Ecological Quality Ratio (EQR) data in rivers or lakes and report the class boundaries values using the BiologyEQRClassificationProcedure table.
3. Data publication
Disaggregated data is preferred even where reporting of aggregated data is still acceptable (e.g. for hazardous substances in rivers or lakes; nitrate, nitrite, ammonium and dissolved oxygen in groundwater). Disaggregated data will be published by EEA.
Data will be also aggregated prior to publication in Waterbase. Annually aggregated data will be used as the basis of assessment in indicator factsheets or reports.
4. Spatial reference data
The time series reported under the WISE SoE Water Quality data flow must be linked to a monitoring site (or to a groundwater body, for data aggregated by water body), using a unique identifier. The location, identification and characteristics of the spatial objects must be provided via the WISE Spatial data flow.
If a monitoring site or water body is reported also under the WFD, then use the WFD identifier as the unique identifier.
During the quality control procedures of the data reported under the WISE SoE Water Quality, the consistency of these identifiers will be checked against the spatial data already reported. (Please note that the spatial data does not have to be reported annually. However, updates to the spatial data (e.g. new monitoring sites, changes in the identifiers, etc.) should be reported.
5. Values below the limit of quantification in disaggregated data
If, for a specific sample value, the measured concentration is below the limit of quantification, then report the limit of quantification value in the "Observed Value" field and report 'True' (or '1') in the boolean "Observed value below LOQ" field.
6. Values below the limit of quantification in annually aggregated data
When preparing annually aggregated data, sample concentrations below the limits of quantification must be treated in accordance to the QA/QC Directive (Commission directive 2009/90/EC of 31 July 2009 laying down, pursuant to Directive 2000/60/EC of the European Parliament and of the Council, technical specifications for chemical analysis and monitoring of water status):
- If a sample concentration value is below the limit of quantification, then, for the mean value calculation only, it must be replaced with a value equivalent to HALF THE LIMIT OF QUANTIFICATION value;
- If the calculated annual mean value of the measurements results is below the limit of quantification value, then report the limit of quantification value in the "resultMeanValue" field and set 'True' (or '1') in the boolean "resultQualityMeanBelowLOQ" field. Use the same rule when reporting minimum, maximum and median values. If the samples in the aggregation had different limits of quantification, then the highest of the different LOQ values must be used in these cases.
7. Reporting data at water body level
The aggregation process should consist of two phases: first, calculate the annual mean value by monitoring site; then use the results to calculate the annual mean value by water body. Using this approach, the influence of different number of samples at monitoring site level is eliminated.
8. Decimal separators and precision of the reported data
Use a decimal point '.' as the decimal separator. Do not use a comma ','.
The general recommendation concerning the decimal precision is as follows:
- Use 1 to 3 decimal places in reporting nutrients (usually in milligrams per litre),
- Use 3 to 4 decimals places in reporting hazardous substances (usually in micrograms per litre).
9. Other recommendations
If disaggregated data is reported, then do NOT report redundant aggregated data.
Please provide long time series without gaps and as complete a geographic coverage as possible.
10. Reporting format and delivery
Data can be delivered in XML files or in MS Excel file format. Use the reporting templates (MS Excel or XML schemas) and these specifications when formatting and collating the data delivery. The templates, as well as the technical specification itself, can be downloaded from the Data Dictionary: click on the Exports icon to expand the list of downloadable files and then select the appropriate output, e.g.:
- To download the technical specification of the dataset in the pdf format, click on 'Create technical specification for this dataset'
- Select 'WISE-SoE_WaterQuality.xls' to download an empty WISE-4 MS Excel template
- If you want to download the full xsd schema file for WISE-4 dataset, select 'WISE-SoE_WaterQuality_schema'
- If you want to download the xsd schema file for an individual table, click on the icon relevant for the selected table in the Exports frame (select 'WISE-SoE_WaterQuality_DisaggregatedData_schema' to download the WISE-4 DisaggregatedData table)
Please do not use formulas in MS Excel files and do not rename the worksheets or column names. The file name can be renamed. Please use easily understandable names.
Delivery can be split into a multiple files if necessary. All the files should be uploaded to the same envelope, if possible.
Upload the data files to the Central Data Repository at http://cdr.eionet.europa.eu/.
A WISE SoE Water Quality folder will be created by the EEA under your country’s collection.
If you have any questions about the format and content of the data request please contact WISE-SoE helpdesk, e-mail: wisesoe.helpdesk@eionet.europa.eu
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