General summary Asia
Table 3 shows the distribution of water withdrawal by region between the three major sectors of water use: agriculture (irrigation and livestock), communities (domestic water supply) and industry. Water requirements for energy (hydropower), navigation, fisheries, mining, environment and recreation, although they may represent a significant part of the water resources, have a negligible net consumption rate. Furthermore, as most countries do not provide separate figures for those items, they are not included in the computation of the regional water withdrawal. Where available, these figures were included in the specific country profiles.
For most countries, data on water withdrawal could be obtained from national statistics although large uncertainties remain on computation methods. For six countries (Bhutan, Cambodia, DPR Korea, Lao PDR, Myanmar and Papua New Guinea) data for water withdrawal could not be found in national reports and estimates from the World Resources Institute (1998) were used instead. It should be noted that these are countries where water resources are not a constraint on economic development.
In Asia, almost 84 percent of the water withdrawal is used for agricultural purposes, compared to 71 percent for the world. The Indian subcontinent and Eastern Asia have the highest level of water withdrawal for agriculture with 92 and 77 percent respectively. The two regions together represent about 82 percent of the total irrigated area in Asia. Figures for agricultural water withdrawal expressed in cubic metres per hectare of irrigated land show large discrepancies between countries which cannot be explained solely by differences in climatic conditions. Rather, their difference is to be found in computation methods. Indeed, with a major regional emphasis on flooded rice irrigation, it is particularly difficult to assess agricultural water use. The gross average for the region is 8 900 m3/ha/year. Figures for China and India, which represent 72 percent of the region's agricultural water withdrawal, are relatively similar: 7 500 and 9 200 m3/ha of irrigated land respectively. However, other countries show much higher values, as is the case of the Philippines, Malaysia, Japan, Republic of Korea, Nepal and Sri Lanka, where agricultural water withdrawal is between 15 000 and 31 500 m3/ha/year. More research is needed to obtain homogenous information on agricultural water use among countries.
Water withdrawal expressed as a percentage of TRWR, which take into account the incoming or border flows and the existing agreements, is a good indicator of the pressure on water resources. Roughly, it can be considered that pressure on water resources is high when this value is above 25 percent, as is the case for India and the Republic of Korea with 34 and 26 percent respectively. China, Japan, DPR Korea and Sri Lanka also have high values with 18.57, 21.26, 18.36 and 19.54 percent respectively. Industrial water withdrawal is particularly important in Eastern Asia (18 percent) and the Far East (16 percent), where the industrial sector is more developed.
The increasing pressure on water resources in north China leads to water scarcity and increased competition for water between agriculture, industries and rapidly growing cities and is usually detrimental to the agricultural sector. The single most important water transfer programme in the region is the Three Gorges project on the Yangtze River, which is intended to transfer 70 km3/year to north China, mostly to satisfy the increasing water demand of the Beijing area.
Figures for produced and treated wastewater are available only for some countries and are often underestimated. In most countries, treatment plants for wastewater are inexistent. Information on re-used treated wastewater exists only for China and Japan, where the re-used treated wastewater is reserved for the industrial sector. In addition, about 40 million m³ and 0.37 million m³ of water are produced by the desalinisation of seawater in Japan and Maldives respectively (Table 4).