Securing The Himalayas As The Water Tower Of Asia

As reported in the July 2013 issue of Asia Policy, a look at the critical environmental importance of the Himalayas:

The crucial role of mountains as the creators and providers of large volumes of freshwater and as the natural storage site of this vital ecosystem service attracted the special attention of world leaders after the United Nations Conference on Environment and Development in 1992.1 This essay addresses the role of the Himalayas as the provider of crucial freshwater supplies to a larger number of people than any other mountain range in the world. The essay first describes the eco-hydrology of the Himalayan region, and then turns to examine the role of the Himalayan rivers in Asia’s economic and demographic growth. It concludes by analyzing the ecological imperative of sustaining the Himalayan waters.

Himalayan Waters: An Eco-hydrological Background

In terms of the number of people who depend on such “water towers” for their survival and well-being, the Himalayas are the most important. The Himalayan region, encompassing the Hindu Kush mountains and the Tibetan Plateau, spans an area of more than 4.3 million square kilometers spread across Afghanistan, Bhutan, China, India, Myanmar, Nepal, and Pakistan. The region stores more snow and ice than anywhere else in the world outside the two poles and thus is popularly known as “the third pole.”2 Containing the highest mountains of the world, the Himalayas act as a great barrier to global atmospheric circulation. The Indian summer monsoon and the East Asian monsoon interact in this environment to provide a large portion of the water supply of Asia. Ten major rivers emerge from the Himalayan region, making it a crucial ecological buffer. These rivers include the Yellow and Yangtze, which emerge from the Qinghai Plateau and provide water to densely populated parts of the north China plain; the Mekong, Salween, and Irrawaddy, which flow southward from Tibet into Southeast Asia; the Ganges-Brahmaputra-Meghna, which drains large areas both north and south of the Himalayas and provides about two-thirds of the total annual river flow for India; and the Indus, which is the lifeline of Pakistan.

The scale of the ecosystem services that the Himalayas provide is almost without parallel in human history. The Himalayan river basins are home to about 1.3 billion people and supply water, food, and energy to more than 3 billion people.3 Human intervention in the flow of these rivers must be based on adequate knowledge of three vital constituents of the Himalayan rivers—water flow, sediment load, and energy potential.

Since a large amount of the precipitation in the high mountain areas is stored in snow cover and glaciers, there are natural delays in the outflow of the melt water. In this way the Himalayan rivers provide crucial water supplies during dry periods. While the importance of high sediment loads in the eco-hydrology of the Himalayan rivers is well-known, knowledge of the amount of sediment carried and its role in the rivers’ morphological dynamics is still at a rudimentary stage. Despite early research on the geological denudation of the Himalayas and the expansion of the Bengal deep-sea fan at the end of the Ganges-Brahmaputra-Meghna Basin,4 accurate information on the generation, transportation, and final deposition of sediment from the Himalayas is difficult to find. In addition, only recently have attempts been undertaken to quantify the amounts of water produced by the Himalayas. Bodo Bookhagen and Douglas Burbank have developed a hydrological budget and established an important correlation between precipitation and run-off in 27 Himalayan rivers of South Asia, starting from the Yarlung Tsangpo in the east to the Indus in the west.5 The relative contributions of rainfall, snow melt, and glacier melt—the three factors that constitute the river flows—vary significantly from the eastern extreme of the Himalayas to the western. For example, Yarlung Tsangpo in the eastern part of the region receives about 34% of its flow from snow and glacier melt, while the Indus in the west depends on melt for 66% of its flow.

Himalayan Waters as Input for the Asian Economic Growth

While irrigation remains the principal form of water use in Asia, in recent decades the Himalayan rivers have also helped power the region’s high rates of economic growth, particularly in burgeoning urban and industrial parts of China and India. To meet rising demand, governments initially took a business-as-usual approach to augmenting water supply. China has undertaken a large-scale project to transfer water from the Yangtze River in the south to the north, while India began trying to link water-rich rivers with those in drier areas. There are three transfer projects in China, though the third one in the province of Sichuan has not materialized yet. The linking project in India has connected some rivers, but the scale of the transfer is not still very high. The cumulative impact of earlier diversion projects led to lower river flows and quickly caused environmental degradation and the loss of related ecosystem services. Water quantity dwindled and water quality was drastically reduced. For example, one of the two mother rivers in China, the Yellow, dried up and had no ability to flow out to the Bohai Sea for long periods.7 The Ganges, one of India’s mother rivers, is now polluted from almost its glacial roots, despite liberal funding from the Indian government for cleaning it. The situation is similar in Bangladesh, Nepal, and Pakistan.

The problem of freshwater scarcity becomes more critical when projected future water requirements are considered. In 2025, water demand in China will reach more than 1,100 billion cubic meters (bcm) in the business as usual approach, while only about 873 bcm of water is presently usable. Similarly, in India there is presently only 1,123 bcm of usable water, while demand is projected to reach 1,180 bcm in 2050. The continued rapid economic growth and improvement in the quality of life in Asia thus depends on sustaining the available supplies of freshwater and innovating a more resource-efficient economic path. This poses a great challenge for water science, engineering, and policy, especially in the region’s two largest and economically strongest countries, China and India.

The urgency of the above objectives becomes absolutely clear when the potential impacts of global warming and climate change on the flows of the Himalayan rivers are considered. According to the International Centre for Integrated Mountain Development:  Mountain systems are particularly sensitive to climate change…. The rate of warming in the Third Pole region is significantly higher than the global average, and the rate is higher at higher altitude, suggesting a greater vulnerability of the cryosphere environment to climate change. This trend is expected to continue. Climate change projections suggest that all areas of South Asia are likely to warm by at least 1°C by the end of the century, while in some areas the warming could be as high as 3.5–4°C. The life and livelihoods of the people in the Third Pole region is challenged due to climate change, and the stability and prosperity of the region affected by the Third Pole is at risk, which will have implications for all of Asia and for the world.8

The deeper crisis is that there is still a large gap in scientific knowledge of these processes and their potential implications for Himalayan rivers. The absence of a dependable database for effective climate modeling that fits the micro-climatic details in the Himalayas is a serious problem in need of immediate attention.9 While Lamadrid and MacClune have made a push toward filling this gap, further research into the environmental sustainability of the Himalayan watershed is an urgent prerequisite for sustained economic growth and development in Asia.10

The Environmental Sustainability of the Himalayan Rivers: A Regional Task of Global Significance

The Himalayas offer suitable landforms for storage dams, and the quickly growing water demands of the surrounding plains have led to the rapid building of dams there. The Xiaolangdi Dam on the Yellow River and Bhakra Dam on the Sutlej River, for example, were heralded as great contributors to economic growth in China and India, respectively. With the passage of time, however, the environmental impacts of dams have generated concerns and environmental movements pushing for a new understanding of the role of engineering interventions in the Himalayan rivers. The Three Gorges Dam on Yangtze River in China and the Tehri Dam on the Bhagirathi River in India generated serious concerns over sustainability. High sediment loads have further complicated matters, since separation of the sediment from water becomes a costly engineering challenge.

Nevertheless, the Himalayan rivers have continued to be the major focus of dam-building efforts. In future decades, hundreds of hydropower dams are slated to be built on the tributaries of the Brahmaputra on the southern aspect in India and Yarlung Tsangpo in China. This river had not been interfered with until recently, and the extent of the strategic environmental implications are not clearly known. In particular, the proposed structural intervention by China at the Yarlung Tsangpo bend has drawn global media attention to the possibility that the Brahmaputra will dry up downstream in India during the lean season. In reality, the Yarlung Tsangpo is a minor contributor to the total flow of the Brahmaputra. Further, snow and glaciers supply about 34% of its total flow.

What is significant in the flow of the Yarlung Tsangpo is not the water but the very large potential for energy generation. A hydropower project at the Yarlung Tsangpo bend would be more attractive for China than a project to physically transfer water. Dams that are being built or planned on the Mekong and Salween rivers require more serious attention with respect to changed flow patterns and reduction in the total flows, if any.

In view of the challenge of food security given the large population in Asia, the task of ensuring the environmental sustainability of the Himalayan rivers is of paramount significance. Further, predicting the impact of global warming and climate change on the Himalayan rivers has attained very high priority for Asia as a whole. It is in the broader regional interest, as much as in their own interest, that the countries sharing the Himalayas take early collaborative steps to address these issues before environmental changes—in particular, climate change—leaves them fewer options. As larger stakeholders, in terms of both population and scientific capability, China and India must play a central role in creating such a collaboration. There is an immediate need for collaborative research to provide greater clarity about the details of hydro-meteorological processes in the Himalayas. The devastating flood in the Indian Himalayan state of Uttarakhand that occurred in June 2013 and killed thousands of people is a case in point.

Further, the task of developing suitable modeling for predicting the impacts of global warming and climate change is equally urgent.12 The controversy over the rate at which the Himalayan glaciers are shrinking shows the need for high-level scientific research on this topic.13 There actually may be more water in total flowing in the Himalayan rivers as a result of increased rainfall under a warmer climate regime. This would reduce the ability of the mountains to store water naturally in snow and glaciers and there may create new pressure for the construction of additional storage structures. On the one hand, the new climate regime may enhance the existing problem of floods in Himalayan rivers, while also leading to greater sediment generation and transportation. On the other hand, the greater availability of rainfall could be a win-win situation if ecologically sustainable and socially acceptable policies for its storage are put in place. The advancement of science and policies for achieving the goal of sustainability is a global challenge that will need to be achieved through extensive regional collaboration at various levels ranging from water science to hydro-diplomacy. Specifically, this is an opportunity for China and India to establish their credibility as leaders in sustainability science and engineering.

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