Espa˝ol || Franšais
      AQUASTAT Home        About AQUASTAT     FAO Water    Statistics at FAO

AQUASTAT metadata

This page explains how metadata is used in the AQUASTAT Main Database. The metadata structure itself is based on the EURO-SDMX structure, which can be consulted for concept definitions. There are three levels of metadata: data-point level, variable level, and database level.

Data-point level

At a data-point level, there might be comments that either add a caveat or further explain the data-point. The metadata presented was harvested from about 15 years of institutional memory, not all of which was external. Several thousand external metadata have been attached to data, along with over 50 000 quality-control internal metadata. Given the substantial nature of this modification, it is possible that some of the metadata are not correctly categorized. Should you identify any inconsistency, please send us an email with comments and suggestions. Regarding the categorization of the metadata, we have selected nine categories, explained as such:

Reference area Is there anything particular about the country? For example: "Includes island X" or "Only region Y was covered" or "These results are only for city Z".
Reference periodAre there any details about the dates? For example: "The average takes into account the average precipitation between 1961-1990" or "Data actually from 1998".
Comparability (geographical)Is there anything that makes this number difficult to compare to numbers in other countries? For example: "The definition calls for using method A, but this country uses method B".
Comparability (over time)Did anything happen to make numbers not comparable to numbers for this country in other years? For example: "The country included the precipitation from a new station in 1998, which makes the data after 1998 incompatible with the older data".
AdjustmentHas any nationally reported data been changed by AQUASTAT? For example: "There was a typo xx in the literature from the country that was corrected to x in the database".
Overall accuracyIs there any known quality issue regarding this data-point? For example: "The country's municipal water withdrawal tripled in five years".
ComponentsAre there any details about what that data-point consists of? For example: "Flow of border rivers is 10, consisting of 5 from river A, 3 from river B, and 2 from river C". Metadata is only entered in the case that the specific component is not another data-point itself. For example, the total area equipped for irrigation will not have metadata stating its components since those components are themselves variables that can be queried.
ObservationsGeneral contextual notes about a country. For example: "The country is one of the driest countries in the world".
MethodologyIf the method by which a value is derived is known but doesn't fit into any of the categories above, it is provided here.

View the Main Database and the metadata now!

Variable level

The next level of aggregation is at the variable level. This metadata can be accessed by clicking on the icon to the right of each variable in the database query page. View the Main Database now!

Database level

The highest level of aggregation is the database level. Below you can find general information about the AQUASTAT modus operandi, properly categorized.

Database nameAQUASTAT main country database

Contact organizationFood and Agriculture Organization of the United Nations
Contact email
Contact acronymFAO
Contact organization unit NRL
Contact URL

Metadata update
Metadata last update10 Jan 2012

Statistical presentation
Data description The data pertains to water resources, water withdrawals and uses, and agricultural water management (including irrigation), although some general statistics are also provided.
Sector coverageWater and irrigated agriculture sectors.
Statistical concepts and definitionsA complete list of the database variables and definitions is available in AQUASTAT's glossary.
Statistical unitGlobal, regional, national.
Statistical populationN/A
Time coverage1960 - present.
Base periodcirca 2005.

Unit of MeasureEach variable's unit is noted in the glossary.

Reference periodFor water resources, the reference period is 1961-1990, unless otherwise noted.

Institutional mandateThis database supports Article 1 of FAO's constitution that requires FAO to "collect, analyze, interpret, and disseminate information related to nutrition, food, and agriculture".

Confidentiality - policyAQUASTAT's terms and conditions are laid out in the User Agreement.
Confidentiality - data treatmentN/A

Release policy
Release calendar policyData is not released on a schedule, but updated continuously based on new data availability.
Release calendar accessN/A
User accessAccess to AQUASTAT data is provided to external users through the AQUASTAT webpage, and through the websites of pre-selected partners that provide AQUASTAT data.

Frequency of disseminationContinuously, as available.

Dissemination format
News releaseMajor updates are announced on AQUASTAT's front page under the "Website updates", as well as via an RSS feed and via Twitter.
PublicationsAQUASTAT publications are listed in the Publications page.
Online databaseThe Main Database is the principal method of data dissemination, although other databases are also available.
Micro-data accessN/A
Other disseminationN/A

Accessibility of documentation
Documentation on methodologyMethodology documents are available under each thematic section.
Documentation on qualityAQUASTAT's procedure to ensure quality results is schematically described in the methodology flowchart.

Quality management
Quality assuranceN/A
Quality assessmentSome variables are easier to gather and standardize than others. Consequently, data quality is perceived to be heterogeneous across the different variables that AQUASTAT gathers. Where possible, harmonization is performed with other agencies to maximize data quality. Frequently, data quality assessments result in significant changes which lead to back-changes in the complete data series.

User needs User needs are varied, but frequently include sub-national and sub-yearly data. While some data is provided at a sub-national level, resource limitations prevent this from being the standard. Data in AQUASTAT is available mostly at a national level, for 5-year periods.
User satisfactionWhile no surveys have been completed, AQUASTAT is held in good esteem by the international community, as evidenced by the fact that AQUASTAT statistics are almost always referenced or used as a point of comparison in any study relevant to national-level water resources, water uses and/or irrigation.
CompletenessSubstantial data gaps exist, as AQUASTAT contains statistics mostly derived from national entities, and performs only limited modelling.

Accuracy and reliability
Overall accuracy No formal quality assessment has been conducted.
Sampling errorN/A
Non-sampling errorN/A

Timeliness and punctuality
TimelinessData is roughly gathered by geographical region. The update process takes on average approximately 2 years.
PunctualityRegional reports are produced punctually as per each deadline.

Comparability - geographicalGiven the number of countries for which AQUASTAT reports information as well as the heterogeneity), data is sometimes not highly comparable. AQUASTAT does attempt to maximize comparability through rigorous quality assurance exercises, for example, by applying a common set of rules with which to evaluate transboundary water resources.
Comparability - over timeTime series, unless otherwise noted are comparable across time.

Coherence - cross domainHarmonization exercises with other agencies are performed frequently and substantial differences are immediately corrected in the AQUASTAT database. Nomenclature for statistics offered by other agencies is not always consistent with AQUASTAT nomenclature. In these cases, the AQUASTAT glossary defines synonyms.
Coherence - internalIncoherent data is adjusted by AQUASTAT in order to maintain internal coherence. Adjusted values are attributed with an appropriate qualifier (also known as flag).

Cost and burdenIn general, updating one country (obtaining, validating, quality-controlling, and uploading data on over 200 variables; writing reports; updating website) requires approximately 40 work-days, shared by national-level and AQUASTAT staff.

Data revision
Data revision - policyData is revised as soon as high quality updates become available. If necessary, present day changes cause back-changing and/or deleting of historic entries.
Data revision - practiseN/A

Statistical processing
Source dataUnless otherwise indicated, data come from government representatives and/or publications from within each respective country. Data not generated by a country is displayed with an appropriate qualifier.
Frequency of data collection Continuous
Data collection methodsMost data is obtained by the use of the AQUASTAT questionnaire. This questionnaire is either forwarded to official government offices, or filled in by a recruited national expert (as monetary resources allow).
Data validationAs described in the methodology flowchart, various steps of validation are performed. The first two levels of validation include human interaction, and are done based on cross-comparison with similar countries as well as historic data for the country in question. The last validation step, prior to saving of new results, is an automated validation step that mathematically checks updated data for consistency and correctness. Almost 200 validation rules are used by this automated validation routine.
Data compilationCalculation rules are predefined which use the latest information from every 5-year period to generate aggregate values.
AdjustmentsSince national-level data is frequently tailored to be useful at a national level and not for international comparisons, data may be manipulated in order to maximize international comparability. Adjusted data is displayed with an appropriate qualifier. Additionally, data is rounded according to the following methodology:
  • 1 111.11 gets rounded to 1111
  • 111.111 gets rounded to 111.1
  • 11.1111 gets rounded to 11.11
  • 1.11111 gets rounded to 1.111
  • 0.111111 gets rounded to 0.1111
  • 0.0111111 gets rounded to 0.0111
  • 0.00111111 gets rounded to 0.0011
  • 0.000111111 gets rounded to 0.0001
  • smaller values are rounded to the first non-zero value. For example:
    0.0000111111 gets rounded to 0.00001


Your access to AQUASTAT and use of any of its information or data is subject to the terms and conditions laid down in the User Agreement.