The below shows the locations of 13 major river basins in Africa.

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...

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...

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...

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...

This graphic illustrates the strong link between areas with high densities of industrial activity and zones of seasonally oxygen-depleted waters. There is a strong link between areas with high densities of industrial activity and zones of seasonal oxygen-depleted waters. In recent years there has been an increasing focus on treating and reducing municipal and industrial waste, and on reducing nitrogen levels in agricultural runoff. However, less...

The infuence of glaciers on seasonal distribution of river fow is strongly dependent on annual temperature and precipitation cycles, and the proportion of the catchment occupied by glacier ice. Figure 4 compares precipitation and river fow data for heavily and lightly glacierized catchments in the European Alps and Peru. In the European Alps, runoff is greater than precipitation in summer in both heavily and lightly glacierized catchments. This...

Simulated contributions of glacier melt (frn/ice melt) to annual total runoff were calculated between 1 and 4%. In the period 1999–2000, when the glacier mass balance of Goldbergkees and Stubacher Sonnblickkees have been observed to be zero or slightly above zero, the annual contribution of glacier melt was calculated as 1% (Fig. 7). The highest monthly contribution in 2000 was 4% for the month of August, and the highest daily glacier melt was 12...

Downstream variation in the impact of glacier recession is illustrated in Figure 5, which shows modelled river fows for idealized catchments under climates representative of the western and eastern Himalaya and a 0.06º C per year warming scenario. In the upper parts of the river basins, where glaciers occupy 95% of the catchment area, the impact of glacier shrinkage is large. River discharges increase until mid-century, after which they de...

Under Indonesian law, areas that qualify for protection are based on slope (>40%), sensitive soil types, elevation (above 2000m), and peat land (>3m), thereby preventing any man-made development within most of the Sumatran orangutan’s habitat. Certain sensitive soil types, including deep peat, buffer zones along river banks and around other water sources, and the upper reaches of water catchment areas.