AQUASTAT Symbols

The AQUASTAT core database symbol scheme has changed to follow FAO corporate Statistical Working System standards for consistency within FAO and provide more information to users.

Here is an explanation to the new symbols:

• No symbol: Official value, data come from one national source (FAO questionnaire on water and agriculture, report, publication, official website, etc.) .
• E: Estimate either calculated as sum or identify (yield) from official values or from an AQUASTAT estimation.
• I: Imputed (carry forward, vertical imputation, linear interpolation)^*.
• X: External value (reported by FAOSTAT or another international agency^**)

^*: Imputation in AQUASTAT is aiming at gap filling to enable aggregates and SDG indicators calculations using data referring to the same year. Imputations types includes:

• Carry-forward: the latest available data is carried over as it is considered still valid. Although the database displays the data-point until a new data is made available to allow for aggregation (such as world total), the data is carried over for 10 years for the SDG calculation.
• Linear interpolation: between two existing official data-points, new data-points are estimated following a linear interpolation reproducing a probable yearly evolution.
• Vertical imputation: If a total exist and all or parts of its components are missing, they are estimated using their latest respective share when available.

^**: Some of the data provided in the AQUASTAT Main Database were generated by other agencies. There are two reasons why the AQUASTAT Main Database includes these numbers:

• A specific variable is outside of AQUASTAT's mandate (ex. population, country area).
• Another agency might have a specific value that replaces either an AQUASTAT data gap or less-dependable value. This is frequently the result of on-going harmonization with other international organizations collecting data on water (Eurostat, OECD and UNSD).

The source of the value of a variable with the X symbol is given in the definition of the variable, which can be accessed by clicking on the (i) icon to the right of each variable in the database query page or in the list below.

FAOSTAT: Variables: Total area, Arable land, Permanent crops, Cultivated area, Undernourishment, Gross domestic product (GDP).

UN Population Division (through FAOSTAT): Variables: Population

UNDP: Variables: Human Development Index (HDI), Gender Inequality Index (GII)

CRU: Variables: Average precipitation in depth

FAO Climpag: Variables: National Rainfall Index (NRI)

WRI (World Resources Institute): Variables: Interannual variability, Seasonal variability

JMP of WHO/UNICEF: Variables: Access to improved drinking water source

Eurostat or UNSD: Variables: Some in: Water resources section and Water use section

OECD: Variables: Some in: Water use section

Data without a symbol comes from one national source that can be the FAO questionnaire on water and agriculture, a report, a publication or an official website.