Provisioning | Water Supply | The Brahmaputra supplies > 80% of Tibetan residents’ water usage and could be included in the western route of the South-to-North Water Diversion Project (Jiang et al., 2017). | The Brahmaputra accounts for 30% of total freshwater in India (Jiang et al., 2017; Singh et al., 2004). The Indian Inter-linking Rivers project has diverted water between the Brahmaputra and its tributaries with other Indian rivers since the 1850s (Yasuda et al., 2017). | Bangladesh greatly depends on water flow from the Brahmaputra (67%) and will face water shortages in dry seasons if too much water is retained by upstream riparian countries, especially India (Chowdhury, 2009; Qadir, 2008). | The Brahmaputra accounts for 100% of total runoff of Bhutanese rivers, and Bhutan covers 5.7% of the total basin area of the Brahmaputra (Yasuda et al., 2017). |
Energy Development | Hydropower in the Brahmaputra Basin is 113 GW, accounting for 17% of China’s and 40% of Tibet’s total hydropower potential, most of which is undeveloped (Jiang et al., 2017; Xu et al., 2002). The Brahmaputra supplies electricity for > 95% of rural residents in Tibet (Development and Reform Commission of People's Government of the Xizang Autonomous Region, 2018a). | The Brahmaputra accounts for 44% of India’s total hydropower potential and > 98% of it is undeveloped (Jiang et al., 2017; Sharma & Kuniyal, 2016). However, hydropower development may result in retaining too much water in the dry season and affect downstream agriculture (Rampini, 2016). The Indian Government has chosen to relocate most downstream communities, and the dense and largely rural poor population is expected to become 50% more urbanized by 2025 compared to today, causing increased demands on energy and natural resources (Ray et al., 2015). | Bangladesh does not generate hydroelectricity on the Brahmaputra, and its energy transitions will largely rely on importing the surplus from the hydropower-rich countries, i.e., the other three riparian nations (Rahaman & Hossain, 2020). Bangladesh has imported hydroelectricity from Bhutan and India and started its investment in hydropower dams in Bhutan in 2016 (Haque et al., 2020; Yasuda et al., 2017). | Bhutan has a potential of 30,000 MW hydropower. Hydropower supplies almost 100% of Bhutan’s electricity needs. A total of 93% of the hydropower potential is untapped (Department of Hydropower & Power Systems, 2019). |
Irrigation and food | Three main tributaries of the Brahmaputra supports all three of the major irrigation zones: Rikeze-Manlan Irrigation Zone, Shangnan-Yalung Irrigation Zone and Lhasa-Moda Irrigation Zone (Development and Reform Commission of People's Government of the Xizang Autonomous Region, 2018a). | Around 90% of withdrawn water is used for agriculture (e.g., wheat and rice), which contributes to > 50% of the economic growth and two-thirds of the employment opportunities for rural residents (Rasul, 2015). | Flows from the Brahmaputra sustain fisheries, forestry and agriculture directly. Indirectly, they also help to keep the salinity levels of land as arable (Baten & Titumir, 2016). Irrigation accounts for 58.6% of the total water demand of the country (Chowdhury, 2009). However, obstructions and withdrawal of water by upstream nations, especially India, cause serious effects on agriculture and the community’s livelihood in north and north-western Bangladesh (Hossain & Majumder, 2019). It was reported that 117 rivers have dried up in Bangladesh (Baten & Titumir, 2016). | Rivers in Bhutan flow in the valleys and most of the farmlands are on the slopes, making it hard to harness the rivers. But most of the small streams and tributaries are used for irrigation (Barua et al., 2018) |
Assisting in navigation and transport | The upper Brahmaputra is not suitable for navigation and transport. | River transport on the Brahmaputra is recorded to have started in 1839 in Assam by the British and it helped railway construction in Assam around 1882 (Singh et al., 2004). The vast network of the Ganges, Brahmaputra and Meghna rivers provides a navigable and green integrated water transport system within India, and with Bangladesh, Nepal and Bhutan (Nagabhatla & Jain, 2013; Rasul, 2013). | Water transport in Bangladesh accounts for ~ 15% of total transport GDP and supports 30% of national freight for 14% of passengers (Chowdhury, 2009). The Ganges, Brahmaputra and Meghna rivers flow into Bangladesh and out to the sea, constituting a vast, cost-effective and green water network for transportation (Rasul, 2015). | The Brahmaputra supports tourism, including river cruises and cross-border trips. Bhutan has been using the Brahmaputra waterways to transport crushed stones to Bangladesh after signing bilateral agreements with Bangladesh since 2015 (Stankevich et al., 2021). |
Aquatic organisms for food and medicines | More than 33 species were found in the upper Brahmaputra (i.e., Yarlung Tsangpo). Sisoridae species, especially Glyptosternum maculatum, are the major commercial fish resources for local people (People's Government of the Xizang Autonomous Region, 2014). | More than 141 fish species belonging to 29 families were recorded in the middle and lower Brahmaputra, of which 41 species are commercially desirable (Bhattacharjya et al., 2017; Vass et al., 2011). | The mangrove wetland ecosystem in Bangladesh provides habitat for > 253 species of inland freshwater fish (Mukul et al., 2018) and supports the livelihood of more than 6 million people who depend on fisheries (Islam & Gnauck, 2008). Fish is the major source of protein (65% of animal protein) in an average Bangladeshi diet (Chowdhury, 2009). | Wild fish is not a major part of the Bhutanese diet, and the Royal Government does not permit commercial fishing. Almost 87% of the fish eaten is imported, with the rest contributed by aquaculture (Ministry of Health, 2021). |
Regulatory | Erosion control, and flood mitigation or regulation | Regulating rivers to prevent large-scale destruction caused by flash floods in South Tibet (Arunachal Pradesh) (Xie & Warner, 2021). India is dependent on China’s hydrological data, especially in the flood season, to prevent and adapt to flash floods and other ecological disasters (Xie & Warner, 2021). North-eastern states in India, including Assam, Meghalaya, Mizoram, Manipur, Tripura, Nagaland, Sikkim and West Bengal, are exposed to great risks of flash floods, soil erosion and erosion along the river channels (Mohanty et al., 2020). Bank stabilization and protection measures broadly adopted by China and India exacerbate erosion and create more sediment load for the whole basin (Fischer et al., 2017). Darby et al. (2015) estimate increases of 52–60% in total sediment load at the end of this century compared to the average sediment load of 1981–2000. | One-third of land in Bangladesh is flooded every year and around 60% of the land can be affected in a high-flood year, causing an average of around 6000 death annually (Rasul, 2015). Flood control and drainage strategies in Bangladesh are mostly designed to increase crop production. However, flood control, drainage and irrigation schemes impede natural water flows, threatening fisheries, navigation, wetlands and other natural resources (Chowdhury, 2009). | Being a mountainous country, most parts experience flash floods from glacier lakes, hence regular works are conducted at reducing and monitoring the water level at the lakes (Tariq et al. 2021). Similarly, the southern low-lying district regularly experiences seasonal flash floods. Twenty-three glacial lakes are prone to bursting and about eight of them lie along the Puna Tsang Chu River (a tributary of the Brahmaputra). It is not clear whether the existing hydropower projects would be able to withstand the force of flash flooding (Yasuda et al., 2017). The Royal Government provides sustainable and integrated water management (Tariq et al., 2021). |
Supporting | Carbon emissions reduction | Hydropower is pivotal for Tibet’s energy transition as it is the largest energy resource and supports grid contributions from wind and solar farms (People's Government of the Xizang Autonomous Region, 2016, 2021) | Hydropower determines India’s de-nuclear energy transition, and around 70% of hydropower potential has not been developed (Sharma & Kuniyal, 2016). Damming the Brahmaputra River has been promoted as a major opportunity to reduce carbon emissions by the Indian Government (Rampini, 2021). | As part of afforestation and reforestation programs, mangrove plantation, reducing logging and transforming to mechanized farming, are three major mitigation strategies adopted by the Bangladesh Government (Chowdhury et al., 2021; Roy & Sims, 2021). | Bhutan is now a negative emission country due to high forest coverage and high contribution from of renewable energy (i.e., hydropower) |
Biodiversity and ecosystem conservation | Yarlung Tsangpo River in the Himalaya Region has the highest biodiversity and most complex ecosystems in Tibet (People's Government of the Xizang Autonomous Region, 2014). For example, 517 species of vertebrates and 2823 species of plants were found in Motuo County in the basin (People's Government of the Xizang Autonomous Region, 2014). | North-eastern India has abundant natural resources. For example, there are 52 different forest types and subtypes in Assam, with more than 3413 freshwater wetlands covering an area of 101,232.50 ha and supporting 20,000 birds (Singh et al., 2004). Over 122 species of mammals and 370 birds are recorded in the Brahmaputra Valley Semi-Evergreen Rain Forests, including many highly threatened species, such as tiger, Asian elephant, greater one-horned rhinoceros, swamp deer, gaur, and clouded leopard (Bhagabati et al., 2006). However, this region is suffering from more intense human activities (e.g., tea plantation extension, timber and wildlife trade) that further threaten these already endangered species (Bhagabati et al., 2006). | The Ganges-Brahmaputra delta is a global biodiversity hot-spot and had > 7,000 endemic plant species, ~ 138 species of mammal, > 566 species of birds, 167 species of reptiles, 49 species of amphibians, 2,493 species of insects, 305 species of butterflies and > 253 species of inland freshwater fish (Mukul et al., 2018). | Many Bhutanese researchers and practitioners in ecology believe that the ecosystem of the main tributaries of Brahmaputra is severely degraded (e.g., Puna Tsang Chu River), including river and mountain ecological systems (Yasuda et al., 2017). Hydropower projects are approved and implemented without adequate risk assessment and mitigation plans (Yasuda et al., 2017). |
Nutrient cycling | It was estimated that about 660 m3/km − 2 of sediment load is brought by the northern and 100 m3 km − 2 by the southern tributaries in India to the main river channel, annually (Sharma & Sharma, 2015). More intense human activities, including the construction of hundreds of dams and weirs in the basin, trap nutrients and affect the fertilization of downstream agricultural land (Huang et al., 2020; Shen et al., 2021; Zhao et al., 2020). | Withdrawal of surface water upstream reduces the groundwater level in Bangladesh and increases the salinity of aquifers in its coastal regions (Chowdhury, 2009). | Washed fertile topsoil from mountains during the monsoon deposits the sediments in downstream lowlands in Bhutan & India (Tariq et al. 2021 & Yasuda et al. 2017) |
Poverty alleviation and contribution to regional development | The Brahmaputra has greatly supported Tibet’s regional development since the 1940s by providing water and electricity for many activities including mining and irrigation, among others (Development and Reform Commission of People's Government of the Xizang Autonomous Region, 2018a). | Agriculture and hydropower development are regarded by the Indian Government as the two pillars for poverty alleviation (Ray et al., 2015). | Agriculture employs around 70% of Bangladesh’s labour force and is the country’s most important economic activity (Bangladesh Bureau of Statistics, 2020). Two (i.e., pre-monsoon and dry) of the three cropping seasons need surface and groundwater irrigation (Chowdhury, 2009). | The hydropower, agriculture, and tourism sectors are the major contributors of GDP in Bhutan, and water forms a major part of it (Tariq et al. 2021). |
Cultural | Recreation and tourism | Tourism contributes to ~ 30% of Tibet’s economic growth, and many tourists come for attractions in the Yarlung Zangbo basin, such as Lhasa, the Grand Canyon and Na Mu Cuo (Development and Reform Commission of People's Government of the Xizang Autonomous Region, 2018b). | Around 50% of foreign tourists are attracted by the 19 tourism hot spots (e.g., Kamakhya temple, Hayagrid Madhab temple and wildlife sanctuaries, including national parks) along the banks of Brahmaputra River (Nayak & Panda, 2016). | Travel and tourism contribute to 4.4% GDP and 3.8% employment. Most tourists are attracted by the natural beauty of Bangladesh, such as rivers, coasts, hills, forests and waterfalls (Roy & Roy, 2015). | Rivers form an integral part of ecotourism and provide recreational facilities like kayaking and rafting in some tourist destinations (Tariq et al. 2021) |
Indigenous culture, ethnics, minorities | The Brahmaputra basin sustains more than 200 indigenous and multi-ethnic communities (Pradhan et al., 2021). Communities in the Brahmaputra River basin speak more than 50 languages and include diverse ethnic groups such as Mishmi, Adi, Apa Tani, Sherdukpen, Monpa, Bhutanese, Lepcha and Bhutia (Gamble, 2019). |
Geopolitical influences | As the upstream nation, China has the initiative to develop the Brahmaputra, and downstream countries will be dependent on China for flow (Jiang et al., 2017). China’s Brahmaputra water security agenda is also driven by strategic military considerations (Xie & Warner, 2021). | India wants to keep its control of the Indus system (Brichieri-Colombi & Bradnock, 2003; Pandey et al., 2020). China’s reservoir construction and rumoured plan to divert water from Tibet to the central can weaken India’s control of water and further decrease its geopolitical influences in the Indus system (Mohanty, 2021; Qadir, 2008). | Bangladesh, as the most downstream country, has limited political voice and power to bargain and is heavily dependent on upstream countries (Jiang et al., 2017), including China, India and Bhutan. | A good bilateral relationship between Bhutan and India has historically avoided conflicts between the countries (Yasuda et al. 2017, Tariq et al. 2021) |
Cultural governance | The Brahmaputra supports the Chinese Government’s transformation plan of Tibet, which is to construct a peaceful and prosperous Tibet (Morcom, 2015; Nima et al., 2007). It represents an ideology of ‘human must conquer nature (人定胜天)’ inherited from Mao by showing the Chinese Government’s ability to control, including the control of rivers (Gamble, 2019; Sinha, 2012). It is key for China to consolidate its control in the region and its sovereignty of the disputed regions (Gamble, 2019). | India aims to consolidate its control in the region and its sovereignty of the disputed regions, such as Arunachal Pradesh (South Tibet) (Gamble, 2019). Legacies of British colonization make India support large-scale farming and exporting schemes. Large dams are regarded as temples of resurgent and progressive India because of their roles in supporting and extending agricultural production (Gamble, 2019). | The Bangladeshi state inherited a resilient colonial structure. There are efforts to establish good governance enabling socio-economic development of the country, although various challenges exist (Ullah & Rahman, 2021). Stable socio-economic development also helps to deal with the impacts of the rise of political Islam, especially Islamist militancy in Bangladesh (Ara & Khan, 2006; Riaz & Fair, 2011). | Every mother of a newborn must be fed water to recondition her body from the ravages of childbirth (Dorji, 2016). Water from the Brahmaputra sustains and secures Bhutan’s history and future (Dorji, 2016). Bhutan’s dual system of governance (religious and administrative) is highly influenced by Buddhism and Hinduism. Both religions consider rivers as a local deity and they hold a high social value. |