Updated: Oct 5
A pivotal role for Interdisciplinary Knowledge
The Brahmaputra is a very important river of Asia, connecting the two largest populated countries of the world, China and India. The river also drains the whole of Bhutan and large parts of western Bangladesh.The name Brahmaputra is identified with the combined flow of three Himalayan tributaries which meet near the town of Sadiya in the Assam state of India. These tributaries are Lohit, Dibang and Siang. The longest of these tributaries is Siang, which is known as Yarlung Tsangpo in upstream Tibet (see map). The origin of Yarlung Tsangpo is at 5150 m the Angsi glacier near Mt. Kailash in western Tibet (China) and from there it flows almost eastwards for about 1700 km. Hence, the same point near Mt. Kailash is also considered in geography as the origin of the Brahmaputra. Yarlung Tsangpo takes a sharp U-turn around the Himalayan peak of Namchi Barwa (7782 m), and then it flows south-westwards. In this course, it enters India near the town of Tuting.
The Brahmaputra flows westwards in Assam and takes a southward turn as it enters Bangladesh downstream of the town of Dhubri. The length of Brahmaputra is 760 km and in Bangladesh the river gets the name Jamuna, of which the length is 337 km. After the river enters Bangladesh, at the gauging station of Bahadurabad, the annual flow of Jamuna is 610 BCM and the annual suspended sediment load is estimated at 710 MT. At the end of its southward journey, Jamuna meets the Ganges near Gualondo, to form the Padma (Figure 1).
The area covered by the Brahmaputra sub-basin is 580,000 sq km, of which 50.5% is in China, 33.6% is in India, 8.1% is in Bangladesh and 7.8% is in Bhutan. Hydrologically, the Brahmaputra river system is part of the larger Ganges-Brahmaputra-Meghna basin, of which the combined flow reaches the Bay of Bengal with the name Lower Meghna, south of the Bangladesh town of Chandpur. From that viewpoint, several analysts have described this river system as the Brahmaputra sub-basin. The Brahmaputra is joined by many tributaries, draining the rain-rich south aspect of the Himalaya. Important among such tributaries range from Subansiri and ends with Tista. Among these are all rivers like Manas and Sankosh, emerging from Bhutan.
The Brahmaputra is a trans-boundary sub-basin characterized by wide diversity in environment, demography, administration, politics, ethnicity, culture, etc. which provide conditions for deeply interdisciplinary knowledge as essential for its effective governance.
Potential for cooperation as well as disputes among the riparian countries is present. There has been some initiation of analytical studies on the scope of interdisciplinary water diplomacy in the Brahmaputra sub-basin (Bandyadhyay et al. 2016; Barua 2018, Yumiko et al., 2018). However, the Brahmaputra is a complex river system and needs much more analytical attention, in particular from an interdisciplinary perspective. As a result, the available studies have not yet been of effective use in generating a comprehensive governance strategy for this river system.
To understand these challenges objectively, knowledge of the characteristic environmental and political features, like precipitation pattern, hydrological profile, geomorphological dynamics, population, land use, irrigation, hydropower policy, etc. is necessary. Besides, human interventions like structures built, or planned by the riparian countries, will have to be considered.
Dynamic State of the Physiography
A very important characteristic of the Brahmaputra sub-basin is a high level of physiographic dynamism, not observed in most other Asian rivers. Robinson et al. (2014) have indicated that in the geological past, the Yarlung Tsangpo was probably flowing through the channels that are now marked forriversIrrawaddy and Salween. Some catastrophic events may have turned the flow of the Yarlung Tsangpo away from eastwards to the southwest, flowing around Namchi Barwa. The river descends sharply from the altitude of the Tibet Plateau near Pe (about 3000 m) with a very high downward gradient providing the flow with great energy for high erosion and physiographic instability. This process is accentuated by the frequent tectonic activities and extreme rainfall events in the Himalaya.
Further downstream, after the 1762 and other earthquakes as well as extreme rainfall events, the mainstream Brahmaputra gradually shifted about 150 km westwards from near Dhaka and the large part of the flow became identified as the new Brahmaputra or Jamuna. The Brahmaputra carries one of the highest sediment loads among all rivers and the exact assessment is full of uncertainty. The annual monsoon high flows and shifting of the Brahmaputra in Assam and Bangladesh during the monsoon is equally an important part of that dynamic state. The approach to the monsoon floods is probably the most significant governance challenge in the Brahmaputra in Assam and Bangladesh. A brief look at the precipitation scenario over the sub-basin will be important for addressing this major environmental challenge that is further complicated due to global warming and climate change.
Precipitation: Spatial and Temporal Variations
To address the governance challenges, it is necessary to understand the spatial and temporal variations of precipitation in the Brahmaputra sub-basin. Further, the mitigation and forecasting of floods are very much related to short periods of extreme rainfall events in specific parts of the sub-basin. Based on the annual precipitation, the area of the Brahmaputra sub-basin can be divided into clear climatic zones. The tributary Yarlung Tsangpo mainly passes through semi-arid areas in Southern Tibet in which the annual precipitation is about 400 mm. As it travels around Namchi Barwa and descends along the south aspect of the Himalaya, the annual precipitation gradually increases. The South Asian monsoon moves from the plains of Assam up to Tibet along the Siang/Yarlung Tsangpo gorge.
As the flow of Yarlung/Siang travels down from Tibet, it gets enriched by increasing monsoon precipitation. As Siang reaches the plains of Assam at Pasighat (150 m), the annual precipitation goes up to about 4000 mm. The annual average figures do not give much explanation of the generation of the Brahmaputra floods. It needs an interdisciplinary knowledge base involving the mountain landscape, the atmospheric circulations and mountain hydrology. The beginning of all rainfall is in the atmosphere and to have early warning on the floods, particularly in Assam, the meteorological processes associated with the interaction of the monsoon and the Himalayan landscape is crucial (Vellore et al. 2014). The upstream mountainous catchments of Lohit, Dibang and Siang are characterized by extreme precipitation events.
Further, extreme events do also occur in the upstream catchments of all the Himalayan tributaries draining the rain rich south aspect, from Subansiri to Tista. Their flow make large additions to the flow of mainstream Brahmaputra. Thus, the river system has areas of low water availability, as in Tibet, and areas of high water availability during the monsoon months, as in the south aspect of the eastern Himalaya. In the post-monsoon period, the sub-basin is not rich in water. The result is high flows or floods, erosion and sedimentation during the summer monsoon months, together with the shifting of the braided river flows. In contrast, water scarcity is there for most of the year. This conflicts with the emerging expansion of sedentary farming, like paddy.
The important in-situ services of the flows of the Brahmaputra sub-basin include navigation and fishery, which provide livelihood options to many people. Scarcity of flow in the lean season seriously affects both agriculture and navigation in Assam and Bangladesh. Further, with summer paddy getting increasing importance in food security in Bangladesh, the pre-monsoon scarcity of water in the Brahmaputra has also become an identity of the Brahmaputra sub-basin as water scarce, as much the monsoon floods. Thus, the division of the Brahmaputra sub-basin based on annual water availability in two parts poses unique governance challenges. Thus, the aspect of scarcity has the potential for generating disputes over shared flows, especially between China and India. The other topic that may also generate disputes, is hydro-power projects. With global warming and climate change providing a brake on the coal based power generation policy, the drop in Yarlung Tsangpo from Pe to Pasighat (Figure 2) and related hydropower potential of about 66,000 MW has received high priority in both China and India.
The China-India Relations on Trans-boundary Brahmaputra
It is in the above background, that the challenges in the governance of this trans-boundary sub-basin will be analyzed. The Brahmaputra is rich in total annual flow as well as hydro-power potential. Fig 2 shows the longitudinal profile of the river bed of Brahmaputra. The huge drop in the altitude of the riverbed from about 3000 m at Pe to about 150 m near Pasighat make a very attractive case for the generation of hydro-electricity. It needs to be stressed that flows in the Himalayan rivers are subject to a high level of uncertainty (Kattelmann, 1987), which itself can often produce trans-boundary disputes. Impacts of global warming and climate change will only increase this uncertainty. Further, with the political sensitivity and ecological complexity of the sub-basin, the traditional approach to governance based on engineering structures alone, will be inadequate. Water science has become highly interdisciplinary now. Knowledge-based on extensive data is now guiding the design of governance institutions. For future interventions to be successful the role of interdisciplinary knowledge will be central. Within the available space for this chapter, all challenges in trans-boundary governance cannot be discussed.
China-India Relations and the Yarlung Tsangpo Projectsuctural interventions made or planned by China on Yarlng Tsangpo have got wide media coverage which needs some clarity. Secondly, what is seen by this author as the primary governance agenda for the Brahmaputra sub-basin as a whole will be presented.
China-India Relations and theYarlung Tsangpo Projects
In the past several years, hydro-power projects on the Yarlung Tsangpo built by China have been the subject of many journalistic writings all over the world and some analysts have even warned of a ‘Water War’ between China and downstream India over the shared river. The commissioning of a series of dams by China around Zangmu on the Yarlung Tsangpo very much fueled such reports. Some of these writings even predicted the ‘drying up’ of the Brahmaputra in Assam as a result of dam construction by China. Indeed, in the context of two most populated countries with ambitious plans for rapid economic growth, competition for enhanced access to limited sources of water is a possibility, leading to prospects of serious conflicts, as perceived for example, by SAWI (2018).
On the other hand, depending on the high level of objectivity in diplomacy, the competition can be replaced by cooperation (Hazarika, 2015). The rise of the ‘Water War Narrative’ has been the result of lack of hydrological clarity on a complex river system since many such writings depend on the very weak database and do not distinguish between the cartographic and hydrological continuity of the Yarlung Tsangpo. It needs to be stressed that at Zangmu, the flow of Yarlung Tsangpo would be a small part of the total flow of the Brahmaputra at downstream Bahadurabad in Bangladesh (about 6-7 per cent). The situation can easily be addressed by diplomats with more openness on the part of China about projects and more willingness to gather technical and social information on the part of the protagonists of the Water War narrative.
Commenting on the improbability of Water Wars over dams on Yarlung Tsangpo, Ho (2017) notes that “The difficulties in managing the Brahmaputra, and the fact that both China and India suffer from water scarcity, have led to predictions that the two countries will fight over water in the future. Despite these predictions, armed conflict in the Brahmaputra is unlikely in the current context.”Instead, she has raised the question “Why are China and India unable to establish robust mechanisms for cooperation on the Brahmaputra River, and how, with little institutionalized cooperation in the Brahmaputra, have both sides managed to keep their riparian relations from creating open conflicts?” Indeed, future governance of the Brahmaputra has to respond to this question urgently. However, this is a localized governance issue for the sub-basin.
Cooperative Governance for the Whole Sub-basin
The greater issue in the sub-basin is to generate an informed and comprehensive governance response to the monsoon floods, to reduce vulnerability and enhance soocio-economic advantages. The governance institution should involve all sub-basin countries; China, India, Bhutan and Bangladesh. In a period when the scarcity of water has become a global problem, the Brahmaputra sub-basin finds annual monsoon floods as a major problem. In the context of the complexity of the climate process in the Himalaya, the meteorology of flood producing rainfall events in the Brahmaputra is still at a stage of evolution (Vellore et al, 2014).
All tributaries from the Himalaya have historically recorded anomalous rainfall and produced floods. The catchments of tributaries Luhit, Dibang, Siang and Subansiri face such precipitations more frequently and flood moderating structures were planned on them without being followed. The impact of monsoon floods in downstream Bangladesh is also quite heavy. The four sub-basin countries have to address the flood moderation with a sense of urgency, for which Bangladesh and India may be the prime mover. China should be a good source of knowledge especially in view of the experiences from the Yellow River (Guoying, 2005), once devastated by floods and sedimentation.
One important dimension of this sub-basin cooperative governance would be the exchange of engineering knowledge among the four countries. Managing flood producing precipitation at the location where it falls would be the role of storage structures in the uplands, thus reducing the potential damage in the downstream parts. In the above background, the central task for effective governance of the mighty river Brahmaputra is the generation of interdisciplinary knowledge.
Jayanta Bandyopadhyay is a scholar who has worked on the ecosystem-based governance of Himalayan rivers for about 35 years. In 2012 he retired from his Professor position in the Indian Institute of Management Calcutta. He has been a member of the Task Force of the Planning Commission of India on Himalaya for the 11th Plan of India and Chair (2006-11) of the Scientific Advisory Committee of the G B Pant National Institute for Himalayan Environment and Development, Almora. He can be reached at firstname.lastname@example.org
Acknowledgement: The author thanks his research assistant Sayanangshu Modak for assisting in making the maps for this article.
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