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World's surface water: evaporation and runoff World's surface water: evaporation and runoff
Because much of the world’s surface water is far from concentrations of human settlements, not all of it is readily usable. Some facts concerning global freshwater concentrations: - It is estimated that the freshwater available for human consumption varies between 12,500 km3 and 14,000 km3 each year (Hinrichsen et al., 1998; Jackson et al., 2001). - Many countries in Africa, the Middle East, western Asia, and some eastern European countries ha...
26 Jan 2009 - by Phillippe Rekacewicz (Le Monde diplomatique), February 2006
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The Mekong River - survival for millions The Mekong River - survival for millions
The Mekong River - survival for millions Following the course of the Mekong River helps to understand the human/river hydrological interdependence. From its source on the Tibetan Plateau it drops 5,000 metres and flows across six countries before reaching its delta. More than a third of the population of Cambodia, Lao PDR, Thailand and Vietnam - some 60 million people - live in the Lower Mekong Basin, using the river for drinking water, food, ir...
26 Jan 2009 - by Philippe Rekacewicz
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Biological oxygen demand - BOD: 1976-2008 Biological oxygen demand - BOD: 1976-2008
The availability of oxygen is one of the most important indicators of the condition of a water body, because dissolved oxygen, or DO, (the amount of oxygen dissolved in water) is necessary for most aquatic organisms, including fish and invertebrates. Some species have very defined lower limits of DO that they can tolerate. Increases in DO can indicate improvements in water quality, such as has occurred in many parts of the world in the last 30 ye...
26 Jan 2009 - by Phillippe Rekacewicz, February 2006
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Trends in capture fisheries and aquaculture Trends in capture fisheries and aquaculture
The levelling off of the global fisheries catch reflects a growing decline in most major fishing areas. Today, these fishing areas are producing lower yields than in the past, and it is unlikely that substantial increases will ever again be possible (FAO, 2000). Inland and marine aquaculture production grew by about 5% annually during the 1950s and 1960s, by about 8% per year during the 1970s and 1980s, and by some 10% per year during the 1990s ...
26 Jan 2009 - by Philippe Rekacewicz
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When the city harms its own water resources When the city harms its own water resources
In areas where surface water is not readily available (located far from areas of need), groundwater is the primary water source. Groundwater aquifers supply an estimated 20% of the global population living in arid and semi-arid regions. Despite their widespread presence, groundwater aquifers in arid areas receive only limited or seasonal recharge, making such aquifers susceptible to rapid depletion. The Northern Sahara Basin Aquifer, for example,...
01 Oct 2009 - by Philippe Rekacewicz
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The WWF living planet index for freshwater The WWF living planet index for freshwater
'The over-exploitation and mismanagement of fisheries, particularly when combined with other man-made stresses, can lead to the collapse of regional fish faunas. In many countries, aquaculture is rapidly increasing in response to declining natural fisheries, often exacerbating the degradation of inland and coastal ecosystems through habitat alteration, pollution and the introduction of alien species' (Revenga et al., 1998). The Freshwater Specie...
26 Jan 2009 - by GRID-Arendal
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Damming the world Damming the world
The construction of large dams - defined as those with walls at least 15 metres high - has increased significantly over the past 50 years. The average height of new dams, estimated at 30-34 m from 1940-1990, increased to about 45 m in the 1990s, due largely to construction trends in Asia. The average area and volume of freshwater reservoirs have also steadily increased, rising to about 50 km2 between 1945 and1970, declining through the 1980s to 1...
26 Jan 2009 - by Phillippe Rekacewicz, February 2006
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Lake Chad: almost gone Lake Chad: almost gone
Straddling the borders of Chad, Niger and Cameroon in West Africa, Lake Chad has been a source of freshwater for irrigation projects in each of these countries. Maps drawn from a series of satellite images show a dramatic decrease in the size of the lake over the past 30 years. Since 1963, the lake has shrunk to nearly a twentieth of its original size, due both to climatic changes and to high demands for agricultural water. Since 1963, the surfac...
06 Nov 2009 - by Philippe Rekacewicz (Le Monde diplomatique), February 2006
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Water scarcity in Africa Water scarcity in Africa
Wetlands are essential in providing and storing freshwater, but today more than half of South Africa’s wetlands have been destroyed or degraded and it is estimated that by 2025 South Africa will suffer from water scarcity.
21 Jun 2011 - by Riccardo Pravettoni, UNEP/GRID-Arendal
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Pressures on the South African coast Pressures on the South African coast
Population growth puts pressure on coastal ecosystems. Increased population means growing demand for land for housing and infrastructure, increased use of living resources for food, and more use of available freshwater resources. The negative environmental impacts of the shipping industry also harm the coastal ecosystem. Impacts from shipping include oil spills and the discharge of ballast water and waste into the sea, which affect the quality of...
21 Jun 2011 - by Riccardo Pravettoni, UNEP/GRID-Arendal
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Hydrogeology Hydrogeology
Most of the Sumatran orangutan's forests inland play a key role in ensuring downstream freshwater supplies, since the non-alluvial inland areas of the region tend to have very little or no underlying groundwater resources.
13 Sep 2011 - by Riccardo Pravettoni, UNEP/GRID-Arendal
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Global flyways of the six subspecies of Red Knot Global flyways of the six subspecies of Red Knot
The Red Knot is a migratory shorebird that travels up to 20,000 km twice a year from its breeding grounds on the high Arctic tundra to its southern non-breeding sites. Along with having one of the longest total migrations of any bird, some populations also fly as much as 8,000–9,000 km between stopover sites in a single flight. As a shellfish-eating specialist avoiding pathogen-rich freshwater habitats, the Red Knot relies on the few large ti...
15 Nov 2011 - by Riccardo Pravettoni, UNEP/GRID-Arendal
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