AQUASTAT-DEFINITIONS
AQUASTAT-DEFINITIONS

DEFINITIONS

Agricultural water withdrawal: (106 m3/yr) Annual quantity of water withdrawn for agricultural purposes including irrigation and livestock watering (see note on agricultural water withdrawal in the next section).

Annual crops: (ha) Physical area under temporary (annual) crops.

Area of the country: (ha) The total area of the country, including area under inland water bodies. Data in this category are obtained from the United Nations Statistical Office, except for Bahrain where the area has increased due to land reclaimed from the sea. The total area of Oman is being revised by the UN. In the meantime, the official government figure has been retained, as agreed with the UN.

Area salinized by irrigation: (ha) Total irrigated area affected by salinization as a result of irrigation. This does not include naturally saline areas.

Average groundwater depletion: (106 m3/yr) Annual amount of water withdrawn from aquifers and which is not replenished (mining of rechargeable aquifers or extraction from fossil aquifers).

Average precipitation: (mm/yr and km3/yr) Double average over space and time of water falling on the country in a year.

Cultivable area: (ha) Area of land potentially fit for cultivation. This term may or may not include part or all of the forests and rangeland. (see the note on cultivable land in the next section).

Cultivated area: (ha) Area under temporary (annual) and permanent crops. This refers to the physical area actually cultivated and does not include land which is temporarily fallow (see the note on arable versus cultivated land in the next section).

Dependency ratio: (%) That part of the total renewable water resources originating outside the country.

Desalinated water: (106 m3/yr) Installed capacity of desalination plants.

Domestic water withdrawal: (106 m3/yr) Annual quantity of water withdrawn for domestic purposes. It is usually computed as the total amount of water withdrawn by public distribution networks, and usually includes the withdrawal by those industries connected to public networks.

Drained area: (ha) The area equipped with subsurface or open drains. It can be broken down into drained areas in full or partial control irrigated areas; drained areas in equipped wetland and inland valley bottoms; and other drained areas, equipped for drainage but not equipped for irrigation. Flood recession cropping areas are not considered as being drained.

Equipped wetlands and inland valley bottoms: (ha) Part of cultivated wetlands and inland valley bottoms which have been equipped with water control structures (intake, canals, etc.). Developed mangroves are included in this category.

Flood-protected area: (ha) Area of land equipped with flood control structures.

Flood recession cropping area: (ha) Area along rivers where cultivation occurs in the areas exposed as floods recede. The special case of floating rice is included in this category.

Full or partial control irrigation: equipped area: (ha) Irrigation schemes carried out and managed either by government, private estates or farmers, and where a full or partial control of the water is achieved. Gardening is included in this category.

Full or partial control schemes: (ha) Areas of large, medium and small schemes, following the criteria used by the country, with the criteria given.

Global renevable water resources: (km3/yr). The sum of internal renewable water resources and incoming flow originating outside the country. This definition is used only for African countries.

Harvested crops under irrigation: (ha) Total harvested irrigated area for the crop for the given year. Areas under double cropping should be counted twice. For permanent crops data generally refer to the total planted area.

Industrial water withdrawal: (106 m3/yr) This sector usually refers to self-supplied industries not connected to any distribution network.

Internal renewable water resources: (km3/yr) Average annual flow of rivers and recharge of groundwater generated from endogenous precipitation.

Irrigation potential: (ha) Area of land suitable for irrigation development, taking into account land and water resources. It includes land already under irrigation.The definition may vary among countries (see note on irrigation potential in the next section).

Micro-irrigation: (ha) Part of the full or partial control area irrigated by micro-irrigation.

Other cultivated wetland and inland valley bottoms:(ha). Part of wetland and inland valley bottoms, which have not been equipped with water control structures but are used for cropping.

Other water withdrawal: (106 m3/yr) This includes all other sectors: energy, mining, recreation, navigation, fisheries and environment. These sectors usually have a very low consumption rate.

Percentage of area irrigated from groundwater: (%) Part of the full or partial control area irrigated from wells (shallow wells and deep tubewells) or springs.

Percentage of area irrigated from surface water: (%) Part of the full or partial control area irrigated from rivers or lakes (reservoirs, pumping or diversion).

Percentage of area irrigated from non-conventional sources: (%) Part of the full or partial control area irrigated from non-conventional sources of water such as treated wastewater or desalinated water.

Percentage of equipped area actually irrigated: (%) Part of the full or partial control area which is actually irrigated. Often, the whole area equipped is not irrigated for various reasons, such as lack of water, absence of farmers, damage, organizational problems, and so forth. It concerns the actual physical areas. Irrigated land that is cultivated twice a year is counted once.

Permanent crops: (ha) Area cultivated with crops that occupy the land for long periods that do not need to be replanted after each harvest. This does not include woodland and forests.

Power irrigated area as percentage of water managed area: (%) Part of the water managed area where pumps are used for water supply. It does not include areas where water is pumped with human- or animal-driven water lifting devices.

Produced wastewater: (106 m3/yr) Annual quantity of wastewater produced in the country. This does not include agricultural drainage water.

Reused treated wastewater: (106 m3/yr) Annual quantity of treated wastewater which is reused.

Rural population: (%). The figures are the UN estimates for 1995 or 1994

Spate irrigation area: (ha) Area of land equipped for spate irrigation.

Sprinkler irrigation: (ha) Part of the full or partial control area irrigated by aspersion (sprinkler).

Surface irrigation: (ha) Part of the full or partial control area under surface irrigation: furrow, border, basin, and flooded irrigation of rice.

Total dam capacity: (106 m3) The total cumulative capacity of all dams.

Total irrigated grain production: (tons) The total quantity of cereals harvested annually in the water managed area.

Total irrigation: Area equipped to provide water to the crops. It includes areas equipped for full and partial control irrigation, spate irrigation areas, and equipped wetland and inland valley bottoms. It does not include flood recession cropping areas. In the text it is also referred to as irrigated area or area under irrigation.

Total number of households in irrigation: Total number of households living directly on earnings from full or partial controlled irrigation schemes.

Total population: (inhabitants) The figures are the UN estimates for 1995 (Near East) or 1994 (Africa)

Total (actual) renewable water resources: (km3/yr) The sum of internal renewable water resources and incoming flow originating outside the country, taking into consideration the quantity of flows reserved to upstream and downstream countries through formal or informal agreements or treaties and reduction of flow due to upstream withdrawal. This gives the maximum theoretical amount of water actually available for the country (see note on the computation of water resources in the next section).

Total water managed area: (ha) The sum of full or partial control irrigation equipped areas, spate irrigation areas, equipped wetland and inland valley bottoms and flood recession cropping areas. It does not include water harvesting areas. Other cultivated wetland and inland valley bottoms are included in this definition, but are reported present only in Africa.

Total water withdrawal: (106 m3/yr) Annual quantity of water withdrawn for agricultural, industrial and domestic purposes. It does not include other withdrawals (see below).

Treated wastewater: (106 m3/yr) Annual quantity of wastewater which is treated.

Water supply coverage: (%) The percentage of urban and rural population with access to safe drinking water (criteria may vary between countries).

Water withdrawal: (106 m3/yr) Gross amount of water extracted from the resources for a given use. It includes conveyance losses, consumptive use and return flow (see note on water withdrawal in the next section).

Other definitions and conventions

Notwithstanding the detailed description of each variable, some problems persist due to the fact that it is not always clearly indicated in the available literature which definition has been used in computing the figures. The most frequent problems encountered in computing the figures are listed below. In addition, a number of terms used in the country profiles but not in the tables are also explained below.

Arable versus cultivated land: The official definition of arable land is 'land under temporary crops, temporary meadows for mowing or pasture, land under market and kitchen gardens, and land temporarily fallow'. In this study, 'land cultivated with annual crops' has been preferred to 'arable land' and refers to the physical area actually cultivated with temporary crops, excluding the temporarily fallow land. However, the way multiple cropping and inter-cropping are accounted for is not always clearly explained in the literature.

Agricultural water withdrawal: Methods for computing agricultural water withdrawal vary from country to country. The figure was reviewed for each country on the basis of crop water requirements and irrigated areas, and comments were added in the country profiles to explain the figure when necessary.

Cultivable land: The notion of cultivable land in arid areas is closely linked to the capacity to provide water to the crops. Assumptions made in assessing cultivable land vary from country to country. In this survey, national figures have been used, whenever available, despite possible large discrepancies in computation methods.

Irrigation potential: Assumptions made in assessing irrigation potential vary from country to country. In most cases it is computed on the basis of available land and water resources, but economic and environmental considerations may also have been taken into account. Some countries include the possible use of non-conventional sources of water for irrigation. Except in a few cases, no consideration is given to the possible double counting of shared water resources. Wetland and flood plains are usually, but not systematically included in irrigation potential.

Water withdrawal: This term includes all the water used for agricultural, domestic and industrial purposes. The use of desalinated and treated wastewater is thus included, although in the strict sense this should be called 'water use' rather than 'water withdrawal'. Desalinated water and treated wastewater are also referred to as non-conventional sources of water.

Agricultural water withdrawal: Methods for computing agricultural water withdrawal vary from country to country. The figure was reviewed for each country on the basis of crop water requirements and irrigated areas, and comments were added in the country profiles to explain the figure when necessary.

Livestock water withdrawal: By default, livestock water withdrawal is accounted for in agricultural water withdrawal. However, some countries include it in domestic water withdrawal.

Computation of water resources: The following terms have been used in the computation of water resources: Internal renewable water resources is the average annual flow of rivers and recharge of groundwater generated from endogenous precipitation. A critical review of the data was made to ensure that double counting of surface water and groundwater was avoided. Total natural renewable water resources is the sum of internal renewable water resources and natural incoming flow originating outside the country. Special rules are used to take into account the flow of border rivers, is the average annual amount of water which would flow into the country in natural conditions, i.e. without human influence. This figure is not time dependent. Total actual renewable water resources is the sum of internal renewable water resources and incoming flow originating outside the country, taking into account the quantity of flow reserved to upstream and downstream countries through formal or informal agreements or treaties and reduction of flow due to upstream withdrawal. It corresponds to the maximum theoretical amount of water actually available for a country at a given moment. The figure may vary with time. Manageable water resources, or development potential, refer to that part of the resources which is considered to be available for development under specific economic conditions. This figure considers factors such as the dependability of the flow, floods, extractable groundwater, minimum flow required for non-consumptive uses etc.

Safe yield of groundwater: The definition varies between countries and is explained in the country profiles. It may or may not include fossil water. For example, in Malta, the safe yield of groundwater is considered less than the renewable groundwater potential in order not to deplete the storage capacity of the main aquifer without causing salt water intrusion. In Qatar, it includes fossil water from the aquifers underlying a large part of the Arabian Peninsula.

Kareze or Qanat: Unlined tunnel in the hillside, bringing water by free flow from underground aquifers to the surface.

Shat or Chott: Salty depression.

Sabkhas: Evaporative areas.

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