At present, approximately 57% of total water withdrawal and 70% of water consumption in the world occurs within the countries of Asia. Table 11-8 presents the dynamics of freshwater use in Asia over the sectors of economic activities. As is evident from this table, agriculture (irrigation in particular) accounts for 81% of total water withdrawal and 91% of water consumption in Asia. The area of irrigated lands in Asia currently amounts to 175 Mha and may increase to 230 Mha by 2025. As Table 11-7 implies, the two most populated regions of south and southeast Asia account for about 68% of water withdrawal and about 69% of water consumption in Asia (see Chapter 4). More than 75% of the total water available in India currently is used for irrigation. As much as 20% is required to meet domestic and municipal needsleaving just 5% for industrial needs. The only river in north India that has surplus water to meet future needs of the country is the Brahmaputra. This river, however, is an international river; other countries such as Bangladesh may not approve of building a dam across some of its tributaries. In peninsular India, only the Mahanadi and Godavari have surplus water, but conveying it to drought-prone areas of the south is problematic. Many states in India need to adopt measures for restricting the use of groundwater to prevent a water famine in the future. China's rapid economic growth, industrialization, and urbanizationaccompanied by inadequate infrastructure investment and management capacityhave contributed to widespread problems of water scarcity throughout the country. Of the 640 major cities in China, more than 300 face water shortages; 100 face severe scarcities (UNDP, 1997).
Taking into account projected dynamics of economic development in the temperate, tropical, and arid and semi-arid regions of Asia, combined with the climate change-imposed effect on hydrological regimes, agriculture and the public water supply would require priority attention in these regions to secure sustainable development and avoid potential intersectoral and international water conflicts. Radical changes in water management strategies and substantial investments will be required in Asia to cope with water problems in the 21st century. Adaptation measures will include legal, institutional, and technical initiatives such as modifying existing and constructing new infrastructure (reservoirs, interbasin water transfer schemes), introducing water-saving technologies, upgrading efficiency of irrigation systems, enhancing wastewater recycling systems, introducing low water-use crops, and implementing groundwater protection programs.
At least 14 major international river watersheds exist in Asia. An integrated and decentralized system of restoration and conservation of the water cycle in these drainage basins is vital to mitigate the negative consequences of natural and externally imposed perturbations. Watershed management is challenging in countries where the people-to-land ratio is high and policy and management are inadequate, prompting use of even the most fragile and unsuitable areas in the watersheds for residential, cultivation, and other intensive uses. This is particularly true for countries such as Bangladesh, Nepal, the Philippines, Indonesia, and Vietnam, where many watersheds suffer badly from deforestation, indiscriminate land conversion, excessive soil erosion, declining land productivity, erratic and unreliable surface and groundwater resources, and loss of biodiversity. Many watersheds in Asia already are stressed by intensive use of the land and other resources and by inhospitable climate (especially in arid and semi-arid Asia), beyond their ability to adequately supply water, prevent floods, and deliver other goods and services. In the absence of appropriate adaptation strategies, these watersheds are highly vulnerable to climate change. Global climate change also may have serious water management implications on the territory of boreal Asia. Recent assessments (Izrael et al., 1997a; CAFW, 1998) for all major Siberian rivers (Ob, Yenisei, Lena) with 42% of the total freshwater inflow to the Arctic ocean show that the main water management problems by the year 2050 will be a consequence of significant annual runoff increases (up to 20%) and difficulties with seasonal inundation and flood control measures.
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