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About the data

3.5

environment

Freshwater Definitions

The data on freshwater resources are based on

to variations in collection and estimation methods.

• Internal renewable freshwater resources are

estimates of runoff into rivers and recharge of

In addition, inflows and outflows are estimated at

the average annual flows of rivers and groundwater

ground­water. These estimates are based on differ-

different times and at different levels of quality and

from rainfall in the country. Natural incoming flows

ent sources and refer to different years, so cross-

precision, requiring caution in interpreting the data,

originating outside a country’s borders are excluded.

country comparisons should be made with caution.

particularly for water-short countries, notably in the

Overlapping water resources between surface run-

Because the data are collected intermittently, they

Middle East and North Africa.

off and groundwater recharge are also deducted.

may hide significant variations in total renewable

Water productivity is an indication only of the

• Renewable internal freshwater resources per

water resources from year to year. The data also

efficiency by which each country uses its water

capita are calculated using the World Bank’s popu-

fail to distinguish between seasonal and geographic

resources. Given the different economic structure

lation estimates (see table 2.1). • Annual freshwater

variations in water availability within countries. Data

of each country, these indicators should be used

withdrawals are total water withdrawals, not count-

for small countries and countries in arid and semiarid

carefully, taking into account the countries’ sectoral

ing evaporation losses from storage basins. With-

zones are less reliable than those for larger countries

activities and natural resource endowments.

drawals also include water from desalination plants

The data on access to an improved water source

in countries where they are a significant source. With-

Caution should also be used in comparing data

measure the percentage of the population with ready

drawals can exceed 100 percent of total renewable

on annual freshwater withdrawals, which are subject

access to water for domestic purposes. The data

resources where extraction from nonrenewable aqui-

are based on surveys and estimates provided by

fers or desalination plants is considerable or where

governments to the Joint Monitoring Programme of

water reuse is significant. Withdrawals for agriculture

the World Health Organization (WHO) and the United

and industry are total withdrawals for irrigation and

Nations Children’s Fund (UNICEF). The coverage

livestock production and for direct industrial use

rates are based on information from service users

(including for cooling thermoelectric plants). With-

on actual household use rather than on information

drawals for domestic uses include drinking water,

from service providers, which may include nonfunc-

municipal use or supply, and use for public services,

tioning systems. Access to drinking water from an

commercial establishments, and homes. • Water

improved source does not ensure that the water

productivity is calculated as GDP in constant prices

is safe or adequate, as these characteristics are

divided by annual total water withdrawal. • Access

not tested at the time of survey. While information

to an improved water source is the percentage of the

on access to an improved water source is widely

population with reasonable access to an adequate

used, it is extremely subjective, and such terms as

amount of water from an improved source, such as

safe, improved, adequate, and reasonable may have

piped water into a dwelling, plot, or yard; public tap

different meaning in different countries despite offi-

or standpipe; tubewell or borehole; protected dug

cial WHO definitions (see Definitions). Even in high-

well or spring; and rainwater collection. Unimproved

income countries treated water may not always be

sources include unprotected dug wells or springs,

safe to drink. Access to an improved water source is

carts with small tank or drum, bottled water, and

equated with connection to a supply system; it does

tanker trucks. Reasonable access is defined as the

not take into account variations in the quality and

availability of at least 20 liters a person a day from

cost (broadly defined) of the service.

a source within 1 kilometer of the dwelling.

and countries with greater rainfall.

Agriculture is still the largest user of water, accounting for some 70 3.5a percent of global withdrawals . . . Percent 100

Domestic

Agriculture

Industry

80

60

40

20

0 Low income

Lower middle income

Upper middle income

High income

World

Source: Table 3.5.

. . . and approaching 90 percent in some developing regions Percent 100

Domestic

Industry

3.5b Agriculture

80

60

Data sources Data on freshwater resources and withdrawals

40

are from the Food and Agriculture Organization of the United Nations AQUASTAT data. The GDP

20

estimates used to calculate water productivity are from the World Bank national accounts data-

0 East Europe Latin Middle Asia & America East & & Central & North Pacific Asia Caribbean Africa

Source: Table 3.5.

South SubAsia Saharan Africa

base. Data on access to water are from WHO and UNICEF’s Progress on sanitation and drinking water (2010).

2011 World Development Indicators

145

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