some countries increasing and some countries decreasing. However, even if water use per capita stays constant at 2008 levels, it appears likely industrial water use will continue to rise because of fast rate of population growth in many of these countries.

The majority of Pakistan’s 1.4 billion m3 yr-1 of industrial withdrawals in 2008 was likely from the Indus Basin, and if industrial water use per capita stays the same might rise to 2.3 billion m3 yr-1 in 2030 and 3 billion m3 yr-1 in 2050. India’s industrial withdrawals in the Indus are unknown, but are likely smaller than Pakistan’s, because few major Indian cities are located in the Indus Basin.

Trends in India’s industrial withdrawals from the Ganges/Brahmaputra are unknown, but are likely increasing over time. One study by the 2030 Water Resources Group (2009) suggests that industrial withdrawals for all of India will quadruple, reaching 196 billion m3 yr-1 in 2030. A large portion of Bangladesh’s 0.8 billion m3 yr-1 of industrial withdrawal in 2008 was taken from the Ganges/Brahmaputra Basin and, if industrial water use per capita stays the same, might rise to 1.1 billion m3 yr-1 in 2030 and 1.2 billion m3 yr-1 in 2050. Similarly, Nepal’s industrial withdrawals of 0.4 billion m3 yr-1 in 2000 are all taken from the Ganges Basin, and if industrial water use per capita stays the same might rise to 0.6 billion m3 yr-1 in 2030 and 0.7 billion m3 yr-1 in 2050. Bhutan uses a relatively trivial amount of water for industrial purposes, a trend that is likely to continue.

Trends in Water Scarcity

As discussed in Chapter 3, we primarily pre sent simple metrics of physical water scarcity. This approach is driven by the limited data available for more sophisticated measures that take into account, for example, economic water scarcity or water quality issues. However, we stress that these other issues may be important and deserve future study. Levels of water stress in the future will also be affected by adjustments to human behavior or technological interventions to make existing water use more efficient, both of which are difficult to predict.

Even without climate change affecting water availability in the study area, many countries would have a significant challenge providing enough water to meet their needs under traditional projections. In this section, the Committee explores how some metrics of water scarcity will change with increases in population and water use as well as with climate change. Because quantitative scenarios of how the hydrological cycle will be affected by climate change were beyond the scope of this report, most of the discussion of climate change is narrative, describing the likely direction of change.

As noted earlier, the simplest way to define physical water scarcity is to take the amount of water in a region and divide by the population. One common set of thresholds defines regions with more than 1,700 m3 person-1 yr-1 as “water sufficient,” while those below this threshold have some degree of water stress (<1,700 m3 person-1 yr-1), chronic scarcity (<1,000 m3 person-1 yr-1), or absolute scarcity (<500 m3 person-1 yr-1) (Falkenmark, 1989; Falkenmark and Lindh, 1974; Falkenmark and Widstrand, 1992; Falkenmark et al., 1989). Using this metric, with population growth (ignoring potential changes in water availability) Pakistan will move from water stress in 2000 (1,400 m3 person-1 yr-1) to chronic scarcity in 2030 (900 m3 person-1 yr-1) and 2050 (700 m3 person-1 yr-1), even without factoring in climatic changes to regional hydrology. Any reductions in flow in the Indus caused by climate change would further intensify this scarcity. The next driest country by this metric is India, which stays classified as water stressed but moves from 1,600 m3 person-1 yr-1 in 2009 to 1,300 m3 person-1 yr-1 in 2030 and 1,200 m3 person-1 yr-1 in 2050. By this simple measure, and ignoring potential changes in water availability, Bangladesh, Bhutan, and Nepal remain classed as water sufficient through 2050.

Another way to define physical scarcity is the ratio of water use to water availability. By this metric, and ignoring potential changes to water availability, the Indus Basin seems the most likely of any of the study area basins to face problems of water scarcity (Figure 3.6). Significant increases in irrigation water use in this basin, particularly during the dry months of November to March, may result in essentially all flow in these months being used for irrigation. Increased irrigation water use in the Ganges, particularly in the dry period of November to May, may likewise result in essentially all flow in these months being used for irrigation (Figure 3.7). One potential response by policy makers would be to attempt to increase storage during the monsoon season so that water would be available for irrigation during the dry season. Even with increases in irrigation water use by Bangladesh, the Brahmaputra

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