Archive for Facts and figures

Facts and figures about water and food

While drinking water intake usually varies between 2 and 3 liters/person/day and other domestic water requirements for personal and household hygiene necessitate between 30 and 300 liters/person/day, the production of food requires much more: between 2,000 and 5,000 liters/person/day.

Most of the water that is used on crop production comes from rain that is stored in the ground (known as green water).

Worldwide, rainfall provides 90% of the water used by crops.

Of the world’s total land area, 13 billion hectares (ha), 12% is cultivated and approximately 27% is used for pasture. Of the 1.5 billion ha used for crops, 277 million ha of this is irrigated (18%).

In terms of population, crops equate to .25 ha/person.

Historically, irrigation comprises between 70% and 80% of all water uses. There are some countries that use up to 90% of their water for irrigation.

As a result of increased cropping intensity, the area of harvested crops under irrigation is expected to increase 30% by 2030.

Also by 2030, the amount of water that is expected to be allocated to irrigation will go up by 14%.

Information from:
the 2nd United Nations World Water Development Report: “Water, a shared responsibility”

Source: UNESCO Water Portal, October 2007

Facts and figures about water and coastal ecosystems

Water bodies have attracted human settlements for thousands of years and, as a result of that draw, humans have altered not only coastlines, but also rivers, lakes and wetlands.

While coastal – and inland/freshwater – fishery harvests have continued to expand due to aquaculture, most of these ecosystems are stressed by overfishing, habitat loss and degradation, the introduction and presence of invasive species, pollution and the disruption of river flows by dams and other diversions.


While attempts have been made to value ecosystems, these have remained poorly understood and complex in nature. The various uses of ecosystems – direct, indirect, and recreational among others – are many and at times hard to quantify.

Coastline estuaries are counted among some of the most productive ecosystems on the planet.

Coastal ecosystems such as coral reefs, estuaries, mangroves and sea-grass beds provide many goods and services including, but not limited to coastal protection, high species diversity tourism, biological cleaning, water purification, breeding and nursing grounds for commercial fish species and CO2 absorption.
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Facts and figures about transboundary water

While historically, experts have concentrated on transboundary surface water, more recently, nations have started to include transboundary groundwater on their agendas as more and more people are depending on groundwater to meet their daily needs.

There are more than 263 internationally shared basins worldwide.

Over 45% of the land surface of the world is covered by basins that are shared by more than one nation. Over 75% of all nations, 145 of them have within their boundaries shared basins. And 33 nations have over 95% of their territory within international basins.

While most basins are shared between just two countries, there are many basins where this number is much higher. There are 13 basins worldwide that are shared between 5 and 8 riparian nations. Five basins, the Congo, Niger, Nile, Rhine and Zambezi, are shared between 9 and 11 countries. The river that flows through the most nations is the Danube, which travels within the territory of 18 nations!

Over 40% of the world’s population resides within internationally shared river basins.

Basins shared by two or more nations account for approximately 60% of the world’s river flow.

Information from:
the Transboundary Freshwater Dispute Database (TFDD) at Oregon State University

Source: UNESCO Water Portal, August 2007

Facts and figures about water and international law

The history of international water treaties dates as far back as 2500 BC, when the two Sumerian city-states of Lagash and Umma crafted an agreement ending a water dispute along the Tigris River.

There are more than 3600 international water treaties dating from 805 AD to 1984 AD.

The UN Convention on the Law of the Non-navigational Uses of International Watercourses was adopted May 21, 1997 after 27 years of development. The Global Convention sets out the basis rights and obligations between States relating to the management of international watercourses.

While the ten-year anniversary of the Watercourses Convention passed in May 2007, only 16 nations have ratified the Convention. For the Convention to enter into force, 35 are needed.

The primary substantive rule of international law is that States must utilize their international watercourses in an equitable and reasonable way.

In the 20th century, only seven minor skirmishes took place between nations over shared water resources while over 145 treaties were signed during the same period of time.

Information from:
the Transboundary Freshwater Dispute Database (TFDD) at Oregon State University

Source: UNESCO Water Portal, July 2007

Facts and figures about desertification

Contrary to popular belief, desertification is not the expansion of deserts. It is the degradation of land in arid, semi-arid and dry sub-humid areas caused mostly by human activities and climactic variations.

One third of the world’s land surface is covered by dryland ecosystems. These areas are very fragile and react strongly to inappropriate land use.

More than 250 million people worldwide are affected by desertification. The real cause for alarm is that another one billion people are at risk, residing in over 100 countries.

Over 70 percent of the world’s drylands (excluding hyper-arid deserts) are degraded.

Not all consequences of the degradation of drylands are felt by those inhabiting the drylands themselves. Dust storms and air pollution are often a result of degraded drylands and negative impacts were felt at long distances in cases such as the Dust Bowl years in the United States, the Virgin Land scheme area of the former Soviet Union in the 1950s and in the African Sahel in the 1970s and 1980s.

It is estimated that the negative impact to annual incomes in areas directly affected by desertification is approximately USD$42 billion per year. And this number only takes into account the “direct” costs.

Information from:
United Nations Convention to Combat Desertification website

Source: UNESCO Water Portal, June 2007