FAO AQUASTAT Information

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FAO AQUASTAT is the FAO’s global water information system, providing data for countries in Africa, Asia, Latin America, and the Caribbean, with a special emphasis on agricultural and irrigation water use. AQUASTAT is widely used as a source of information on groundwater use.

AQUASTAT provides country profiles with general information on the geographical and economic situation of each country, and more detailed information on surface water and groundwater resources, water use, and water management. The aim is to describe the particularities of the country and problems relating to the development of the water resources and, in particular, irrigation. There is information on irrigation trends; existing policies and legislation relating to water use in agriculture; possible treaties and agreements between countries; and prospects for water management in agriculture are presented.

The AQUASTAT database holds water statistics at a country level. The statistics are based on the best available data and analysis techniques, but even so, there are data gaps for many countries. These gaps are often worse for groundwater, because groundwater use is more difficult to measure directly than surface water use. This is especially the case for agriculture, as large scale irrigation schemes, which are easier to measure, are usually based on surface water. By contrast, groundwater-based irrigation and other agricultural use in Africa is dominantly small-scale and managed by individual farmers or communities, and so is very difficult to measure and record. AQUASTAT uses modelling to fill in some of these data gaps. It should be recognised that these modelled data may not be accurate.

We have included key FAO AQUASTAT groundwater statistics, and other water statistics that may be useful to those working with groundwater, in the country pages of this Atlas. These statistics provide a very useful overview of the extent of groundwater resources and use in each country, compared to surface water resources, and allow comparison between countries.

Explanations of some AQUASTAT variables, including all those quoted in the Atlas, are given in the tables below. These are based on the FAO AQUASTAT glossary.

Note that the units quoted in the Atlas and in the table below may be different from those quoted in AQUASTAT.

Key groundwater resource statistics

AQUASTAT Variable	Explanation
Groundwater produced internally (groundwater recharge) (million cubic metres/year)		This is AQUASTAT's statistic for long term annual average groundwater recharge, derived from precipitation within the country boundary. Estimated by calculating an annual infiltration rate (in arid countries) or calculating river base flow (in humid countries).
Estimated total renewable groundwater (million cubic metres/year)	AQUASTAT calculates this as the sum of internal renewable groundwater resources (i.e. groundwater recharge - called by AQUASTAT 'groundwater produced internally') and external renewable groundwater resources (i.e. groundwater entering/flowing into the country). I.e., this is all recharge inside the country plus all groundwater flowing into the country from outside.
Exploitable: Regular renewable groundwater resources (million cubic metres/year)	This is defined as the groundwater resources available for development, taking into account environmental, economic and engineering factors. It is specifically defined as the average groundwater flow available 90% of the time and economically/environmentally viable to extract. AQUASTAT states that estimation methods for this vary from country to country, so it may be difficult to use this to compare between countries.
Fresh groundwater withdrawal (primary and secondary) (groundwater abstraction) (Million cubic metres/year)	Includes primary and secondary groundwater withdrawals (abstractions). Primary groundwater withdrawal is groundwater that has not been abstracted before; secondary is groundwater that was previously abstracted and returned to an aquifer (e.g., including irrigation returns or recharge of waste water). In practise, distinguishing between primary and secondary withdrawals is rarely possible. Additionally, estimating groundwater abstractions in most African countries is very difficult, because they are widely distributed and often unrecorded. The estimates of groundwater withdrawal (abstraction) are likely to be calculated differently in different countries.
Groundwater: entering the country (million cubic metres/year)	Defined as the long term average annual quantity of groundwater entering the country that is not submitted to treaties or secured through treaties. Another similar AQUASTAT variable, (Groundwater: accounted inflow), has not been included in the Atlas: this is defined as the long term average annual quantity of groundwater annually entering the country, taking into consideration eventual treaties. There are no countries in Africa with agreed treaties on the quantity of groundwater entering the country, and so there is no practical difference between these two variables. Additionally, very few countries in Africa hold any data on any groundwater inflows from outside the country.
Groundwater: leaving the country to other countries (Million cubic metres/year)	Defined as the average annual quantity of groundwater leaving the country, without treaties. It refers to groundwater flowing to other countries, NOT any groundwater that flows to the sea for countries located next to the sea. Another similar AQUASTAT variable, (Groundwater: accounted outflow to other countries), has not been included in the Atlas. This is defined as the long term average annual quantity of groundwater leaving the country that is not submitted to treaties or secured through treaties. There are no countries in Africa with agreed treaties on the quantity of groundwater leaving the country, and so there is no practical difference between these two variables. Additionally, very few countries in Africa hold any data on any groundwater outflows to other countries, or to the sea.

Key general water resource statistics

AQUASTAT Variable	Explanation
Total renewable water resources (million cubic metres/year)	This is defined as the sum of internal renewable water resources and external renewable water resources. It corresponds to the maximum theoretical yearly amount of water available for a country at a given moment. It is estimated as: [Total renewable surface water] + [Total renewable groundwater] - [Overlap between surface water and groundwater]
Total exploitable water resources (million cubic metres/year)	Estimated as the sum of [Exploitable: total renewable surface water] + [Exploitable: regular renewable groundwater]. Note that methods of estimating exploitable water resources vary from country to country.
Total internal renewable water resources (cubic metres/inhabitant/year)	Estimated by: [Long term average river flow] + [Long term average recharge (groundwater produced internally)] - [Overlap from the sum of surface water and groundwater resources] / [Population].
Freshwater withdrawal as % of total renewable water resources (%)	This is defined as total freshwater withdrawn (abstracted) in a given year, expressed as a percentage of the total renewable water resources. It is estimated as: [Total freshwater withdrawal (primary and secondary)] / [Total renewable water resources] * 100

Key general water supply and use statistics, including for agriculture

AQUASTAT Variable	Explanation
Total/Rural/Urban population with access to safe drinking water (%)	This is the percentage of the total, rural or urban (respectively) population that uses improved water sources. An improved source is defined as one that is likely to provide "safe" water, such as a household connection, a borehole, etc. Note that the lack of current information does not yet allow a relationship to be established between access to safe water and access to improved sources, but WHO and UNICEF are examining this relationship.
Population affected by water related disease (per 1000 inhabitants)	AQUASTAT defines three types of water-related diseases on which to base this statistic: (i) water-borne diseases, which arise from infected water and are transmitted when the water is used for drinking or cooking (for example cholera, typhoid); (ii) water-based diseases, in which water provides the habitant for host organisms of parasites ingested (for example shistomasomiasis or bilharzia); and (iii) water-related insect vector diseases, in which insect vectors rely on water as habitat but transmission is not through direct contact with water (for example malaria, onchocerciasis or river blindness, elephantiasis).
Industrial water withdrawal (all water sources) (million cubic metres/year)	This is the annual quantity of self-supplied water withdrawn (abstracted) for industrial uses. It can include water from primary renewable and secondary freshwater resources, as well as water from over-abstraction of renewable groundwater or withdrawal from fossil groundwater, direct use of agricultural drainage water, direct use of (treated) wastewater, and desalinated water. This sector refers to self-supplied industries not connected to the public distribution network. It includes water for the cooling of thermoelectric and nuclear power plants, but it does not include hydropower. Water withdrawn by industries that are connected to the public supply network is generally included in municipal water withdrawal.
Municipal water withdrawal (all water sources) (million cubic metres/year)	This is the annual quantity of water withdrawn (abstracted) primarily for the direct use by the population. It can include water from primary renewable and secondary freshwater resources, as well as water from over-abstraction of renewable groundwater or withdrawal from fossil groundwater, direct use of agricultural drainage water, direct use of (treated) wastewater, and desalinated water. It is usually calculated as the total water withdrawn by the public distribution network, and therefore in some countries it includes that part of industrial and (urban) agricultural withdrawal which is connected to, and derived from, the municipal network.
Agricultural water withdrawal (all water sources) (million cubic metres/year)	This is the annual quantity of self-supplied water withdrawn (abstracted) for irrigation, livestock and aquaculture purposes. It can include water from primary renewable and secondary freshwater resources, as well as water from over-abstraction of renewable groundwater or withdrawal from fossil groundwater, direct use of agricultural drainage water, direct use of (treated) wastewater, and desalinated water. Water for the dairy and meat industries and industrial processing of harvested agricultural products is included under industrial water withdrawal.
Irrigation water withdrawal (all water sources) (million cubic metres/year)	This is the annual quantity of water withdrawn (abstracted) for irrigation purposes. In the AQUASTAT database water withdrawal for irrigation is a sub-set of agricultural water withdrawal. The amount of water withdrawn for irrigation by far exceeds the consumptive use of irrigation because of water lost in its distribution from its source to the crops. The term "water requirement ratio" (sometimes also called "irrigation efficiency") is used to indicate the ratio between the net irrigation water requirements or crop water requirements, which is the volume of water needed to compensate for the deficit between potential evapotranspiration and effective precipitation over the growing period of the crop, and the amount of water withdrawn for irrigation including the losses.
Irrigation water requirement (all water sources) (million cubic metres/year)	This is the quantity of irrigation water (not including precipitation (rainfall) or soil moisture) that is needed for normal crop production. It is the amount of water to ensure that crops receive their full crop water requirement (i.e. the irrigation consumptive water use, as well as, where relevant, extra water for flooding of paddy fields to facilitate land preparation and protect the plant and for leaching salt when necessary to allow for plant growth). It is usually expressed in water depth (millimetres) or water volume (m3) and may be stated in monthly, seasonal or annual terms, or for a crop period. It corresponds to net irrigation water requirement.
Total area of country cultivated (%)	This is calculated as: [Cultivated area (arable land + permanent crops)] / [Total area of the country] * 100
Area of permanent crops (ha)	Permanent crops are sown or planted once, and then occupy the land for some years and need not be replanted after each annual harvest, such as cocoa, coffee and rubber. This category includes flowering shrubs, fruit trees, nut trees and vines, but excludes trees grown for wood or timber, and permanent meadows and pastures.
Cultivated land (arable and permanent crops) (ha)	This is the sum of the arable land area and the area under permanent crops, calculated by: [Arable land area] + [Permanent crops area]
Area equipped for irrigation by groundwater (ha)	This is the part of the total area equipped for irrigation that is irrigated from wells (shallow wells and deep tube wells) or springs.
Area equipped for irrigation by mixed surface water and groundwater (ha)	This is the part of the area equipped for irrigation that is irrigated from mixed surface water and groundwater.

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