Major Environmental Concerns  

[ Land | Forest | Biodiversity | Water | Marine & Coastal Environments | Urban & Industrial Environments ]

Underlying Causes

[ Social | Economic | Institutional | Environmental ]

The region has arid and semi-arid areas as well as humid tropical areas with high precipitation. It has some of the world's largest rivers-the Ganges ( Ganga ), Brahmaputra , Chang Jiang (Yangtze Kiang), and Yenisei -and numerous small rivers in the insular countries of South-East Asia and the Pacific. There are also a substantial number of natural lakes. Among the largest are Dongting-hu in China , Tonle Sap in Cambodia , and Kasumigaura in Japan . The region is also characterized by extensive ground-water resources; in some of the small island states, such as Maldives , Kiribati , Tuvalu , and the Federated States of Micronesia , ground water is the main source of fresh water.

Though comparatively well endowed with water resources, only a part of the renewable water resources can be extracted and used, owing to the high variability of streamflow between low water and flood seasons, the inaccessibility of some watercourses, and the lack of storage sites on many catchments (ESCAP, 1995a). The total average annual renewable water resource in the region is estimated to be approximately 13,000 cubic kilometres (WRI/UNEP/UNDP, 1994).

The per capita availability of water varies from about 186,000 cubic metres per year in Papua New Guinea to just over 200 cubic metres in Singapore (WRI/UNEP/UNDP/WB, 1996). (See Table 2.3.) Countries such as Afghanistan and Iran suffer from chronic water shortages due to aridity, while parts of China and India experience the same problem primarily due to high population density.

Water pollution in countries in Asia and the Pacific is caused mainly by domestic sewage, industrial effluents, and runoff from activities such as agriculture and mining. The severity of water quality problems in the region is summarized in Table 2.4.

The problem of pathogenic pollution is quite severe in South Asia , South-East Asia , the Pacific Islands , and China ; only in industrial countries such as Japan , Australia , and New Zealand is the problem relatively minor. Pathogens generally come from domestic sewage that is discharged untreated into watercourses. South Asia and China are most severely affected by organic matter pollution, the main source of which is effluent from the pulp and paper and food industries.

Lake eutrophication is a significant but localized concern in a number of countries. A survey by UNEP and the International Lake Environment Committee (ILEC) shows that 54 per cent of the lakes in South-East Asia suffer from eutrophication problems (UNEP, 1994). This subregion's inland water bodies are also affected by the presence of pathogenic agents, while many rivers carry enhanced nutrient and pollutant loads resulting from changes in land use, industrialization, and urbanization.

Discharge of mine tailings and development of industrial areas with direct discharge of pollutants into neighbouring river systems has resulted in hot spots of heavy metal pollution throughout the region.

In the small island countries, salinization affects the ground-water resources severely due to the intrusion of sea water. In Thailand , the rapid lowering of the water table due to excessive extraction of ground water has caused the shallow aquifers in Bangkok to become contaminated with sea water. The overwithdrawal of ground-water reserves has also caused land subsidence in cities such as Bangkok and Jakarta . In Bangkok , for instance, land has subsided in some places by 0.5-0.6 metres over the last 20-25 years, which has aggravated the city's flood problems (ESCAP, 1995a). In countries like Bangladesh , salinity and sedimentation are occurring largely as a result of upstream water withdrawal.

The fresh-water withdrawals in Asia and the Pacific range from 15 to 1,400 cubic metres per person per year (WRI/UNEP/UNDP, 1994). Agriculture accounts for 60-90 per cent of the annual water withdrawal in most countries of the region, with the highest proportion in Afghanistan (99 per cent). (See Table 2.3.) The demands for domestic and industrial uses are increasing in the region due to the high rates of urbanization and industrialization. The demand for water will continue to rise in the region in parallel with population growth.

United Nations Environment Programme