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Threats to coral reefs in Eastern Africa Threats to coral reefs in Eastern Africa
Human land use along coasts and in major river basins can threaten coral reefs through toxic material inputs to coastal ecosystems. This graphic shows the areas of low, medium and high estimated threats to coral reefs on Africa's eastern coast.
17 May 2005 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Dates of river ice break-up in the Arctic Dates of river ice break-up in the Arctic
Dates of river ice break-up in the Arctic
21 Mar 2006 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Unalakleet community in Alaska Unalakleet community in Alaska
Location and Climate: Unalakleet is a small coastal community on Norton Sound, at the mouth of the Unalakleet River, 395 miles northwest of Anchorage, Alaska. Unalakleet has a sub-Arctic climate with considerable influence of the nearby sea when Norton Sound is ice-free, usually from May to October. Winters are cold and dry.
21 Mar 2006 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Dates of river ice freeze-up in the Arctic Dates of river ice freeze-up in the Arctic
Presenting the relative dates of river freeze-up in the Arctic and the climatic condititions surrounding that, thus outlining the relative changes in temperature and conditions throughout the circumpolar Arctic.
21 Mar 2006 - by Philippe Rekacewicz, UNEP/GRID-Arendal
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Dissolved phosphate levels: concentrations at river mouths Dissolved phosphate levels: concentrations at river mouths
Phosphorus is naturally present in water, primarily as inorganic and organic phosphates. Phosphates can enter aquatic environments in several ways: from the natural weathering of minerals in the drainage basin, from biological decomposition, or as runoff from human activity in urban and agricultural areas. A comparison of the major watersheds between the two decades showed that northern Europe and North America had lower phosphate concentrations...
26 Jan 2009 - by Phillippe Rekacewicz, February 2006
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Water Scarcity Index Water Scarcity Index
Water overuse is damaging the environment in many major basins. High overuse tends to occur in regions heavily dependent on irrigated agriculture, such as the Indo-Gangetic Plain in south Asia, the North China Plain and the High Plains of North America, and in areas undergoing rapid urbanization and industrial development. An estimated 1.4 billion people now live in river basin areas that are ‘closed’ (in that water use exceeds minimum recharge l...
13 Sep 2009 - by Philippe Rekacewicz, February 2006
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The water cycle The water cycle
Environment water transport system. The water cycle consists of precipitation, vapour transport, evaporation, evapo-transpiration, infiltration, groundwater flow and runoff. Figure 1 explains the global water cycle, illustrating how nearly 577,000 km3 of water circulates through the cycle each year. A table of estimated residence times shows the approximate times that water resources exist as biospheric water, atmospheric water and so on. The w...
01 Feb 2008 - by Philippe Rekacewicz , UNEP/GRID-Arendal
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Freshwater use by sector at the beginning of the 2000s Freshwater use by sector at the beginning of the 2000s
The agricultural sector is by far the biggest user of freshwater. Analysis indicates that: - In the United States, agriculture accounts for some 49% of total freshwater use, with 80% of this volume being used for irrigation (Shiklomanov, 1999). - In Africa and Asia, an estimated 85-90% of all freshwater used is for agriculture (Shiklomanov, 1999). - According to estimates for the year 2000, agriculture accounted for 67% of the world’s total fr...
26 Jan 2009 - by Philippe Rekacewicz (Le Monde diplomatique)
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The disappearance of the Aral Sea The disappearance of the Aral Sea
The demise of the Aral Sea in central Asia was caused primarily by the diversion of the inflowing Amu Dar’ya and Syr Dar’ya rivers to provide irrigation water for local croplands. These diversions dramatically reduced the river inflows, causing the Aral Sea to shrink by more than 50%, to lose two-thirds of its volume, and to greatly increase its salinity. At the current rate of decline, the Aral Sea has the potential to disappear completely by 20...
26 Jan 2009 - by GRIDA
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Nitrate levels: concentrations at river mouths Nitrate levels: concentrations at river mouths
Nutrients are essential to life. In aquatic systems, nitrogen and phosphorus are the two nutrients that most commonly control the growth of aquatic plants, algae and bacteria. Nitrogen and phosphorus are considered to be the primary drivers of eutrophication of aquatic ecosystems, where increased nutrient concentrations lead to increased primary productivity. Some systems are naturally eutrophic, whereas others have become eutrophic as a result o...
26 Jan 2009 - by Philippe Rekacewicz
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Tigris and Euphrates rivers fragmentation Tigris and Euphrates rivers fragmentation
It has been predicted that access to water will create conflict between countries. In Africa, central Asia, west Asia and the Americas, some countries are already arguing fiercely over access to rivers and inland seas, and confrontations could arise as water shortages grow (Gleick, 2000). Countries currently or potentially involved in international disputes over access to river water and aquifers include: - Turkey, Syria and Iraq (the Tigris and...
26 Jan 2009 - by Philippe Rekacewicz
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Level of river fragmentation and flow regulation Level of river fragmentation and flow regulation
River fragmentation - The interruption of a river’s natural flow by dams, inter-basin transfers or water withdrawal - is an indicator of the degree to which rivers have been modified by man (Ward and Stanford, 1989, and Dynesius and Nilsson, 1994, as cited in Revenga et al., 2000). A fragmentation analysis carried out by the University of Umea and the World Resources Institute showed that, of 227 rivers assessed, 37% were strongly affected by fra...
26 Jan 2009 - by Philippe Rekacewicz (Le Monde diplomatique), March 2006
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Water supply per river basin in 1995 and 2025 Water supply per river basin in 1995 and 2025
Although the absolute quantities of freshwater on earth have always remained approximately the same, the uneven distribution of water and human settlement continues to create growing problems freshwater availability and accessibility.
26 Jan 2009 - by Philippe Rekacewicz,February 2006
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Freshwater alkalinity: 1976-2008 Freshwater alkalinity: 1976-2008
Alkalinity is commonly used to indicate a water body’s capacity to buffer against acidity; that is, the ability to resist, or dampen, changes in pH. Thus, alkaline compounds in water, such as bicarbonates, carbonates, and hydroxides, lower the acidity of the water and increase the pH. Alkalinity (as CaCO3) was analysed for all sampling stations available at the continental level. Concentrations remained reasonably steady between the two decades ...
26 Jan 2009 - by Philippe Rekacewicz (Le Monde diplomatique), February 2006
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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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Africa’s rivers and lake basins cross many borders Africa’s rivers and lake basins cross many borders
The below shows the locations of 13 major river basins in Africa.
26 Jan 2009 - by Philippe Rekacewicz (Le Monde diplomatique), 2007
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Renewable surface water produced internally Renewable surface water produced internally
It is difficult to determine the amount of renewable water produced internally from the total renewable water resources (external and internal). However the FAO gives a rather precise definition of this indicator. Internal Renewable Water Resources (IRWR) includes: - Average precipitation: long-term double average over space and time of the precipitation falling on the country in a year. - Surface water produced internally: long-term average an...
26 Jan 2009 - by GRID-Arendal
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Main world’s river basins Main world’s river basins
Reservoirs are artificial lakes, produced by constructing physical barriers across flowing rivers, which allow the water to pool and be used for various purposes. The volume of water stored in reservoirs worldwide is estimated to be 4,286 km3 (Groombridge and Jenkins, 1998). Wetlands include swamps, bogs, marshes, mires, lagoons and floodplains. The 10 largest wetlands in the world by area are: West Siberian Lowlands (780,000-1,000,000 km2), Ama...
26 Jan 2009 - by Phillipe Rekacewicz, February 2008
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Freshwater resources: volume by continent Freshwater resources: volume by continent
Glaciers and ice caps cover about 10% of the world’s landmass. These are concentrated in Greenland and Antarctica and contain 70% of the world’s freshwater. Unfortunately, most of these resources are located far from human habitation and are not readily accessible for human use. According to the United States Geological Survey (USGS), 96% of the world’s frozen freshwater is at the South and North Poles, with the remaining 4% spread over 550,000 k...
01 Oct 2009 - by Philippe Rekacewicz (Le Monde diplomatique)
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