The Siang River:
The Brahmaputra River is a 2880 km-long transboundary river flows through China, India and Bangladesh.
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The river originates from the Ansi Glacier at an altitude of 5300m about 63 km southwest of Manasarovar Lake close to Mount Kailash in the southwest Tibet and then flows 1700 km within the Tibet Autonomous Region of China, 920 km through Arunachal Pradesh and Assam, India and 260 km in Bangladesh before it drains into the Bay of Bengal.
The river is known as Yarlung-Tsangpo from its origin to Indo-Tibet border. In western Tibet, it flows from west to east parallel to the Himalayan mountains and around the snow-capped massif of Namche Burwa and Gyala Peri and enters into Arunachal Pradesh at Kepang La, near Gelling taking u-turn towards south. It is called Brahmaputra’s Great Bend. Tuting located at an altitude of 1240m above mean sea level on the bank of Siang river at a distance of 34 km south of Line of Actual Control (LAC) and 170 km north of Yingkiong situated at 200m altitude.
Slope of the Brahmaputra River
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The catchment area of the Siang river is 250594sqkm up to Pasighat out of which 14038sqkm lies in India. Most of the catchment area falling in Tibet is affected by snow and rainfall characteristics are different from Indian areas where river is mainly fed by rain water. The part of Siang basin in India is bounded on the north by eastern Himalayas, on west by Subansiri Basin and on east by Dibang Basin. It flows through Arunachal Pradesh in a more or less southerly direction for a distance of 226 km through steep mountainous gorges before reaching Pasighat having elevation 152m. Near Pasighat, the river flows in a braided pattern with as many as four channels due to mild slope and silt deposits. River terraces are also noticeable along the river stretches between Yinkiong and Pasighat.
From Pasighat, the Siang flows another 52 km before it is joined by two major rivers from east and north-east namely the Lohit and the Dibang, a short distance upstream of Kobo near Sadiya (El 123m) to form the Brahmaputra. The river receives numerous tributaries from both sides all along its course thereby progressively growing in its size.
The river is known as Yarlung Tsangpo in Tibet, Siang in Arunachal Pradesh, Brahmaputra in Assam and Jamuna in Bangladesh. The Brahmaputra with average annual flow of 615 billion cubic meter is one of the largest rivers in the world by annual yield and its tributaries provide significant ecological, cultural, and economic services to millions of people residing in Tibet (China), North-eastern India and Bangladesh. Siang river contributes 25-33% of water to mighty Brahmaputra.
The Brahmaputra River course
Water availability:
The average annual rain fall in the Indian catchment is about 3251 mm while the maximum and minimum temperatures are 40° C and 5° C respectively. The maximum rainfall is experienced during the month of June to September with occasional rainfall in May and October. Heavy pre-monsoon rains are also experienced in February and March. Siang river after entering Arunachal Pradesh travelled about 204 km to meet Siyom, a major tributary which contributes 30% to the discharge of Siang at Pangin. The average monsoon and non-monsoon peak discharges at Pangin are 3170 and 1132 cum/sec. Before reaching confluence with Siyom a few streams also join the river Siang contributing about 20% discharge. The flow entering Arunachal Pradesh can be assumed 50% of the discharge at Pangin. It implies that maximum and minimum average discharges entering Arunachal Pradesh is about 1600 and 550 cum/sec respectively. Average annual discharge of Siang river is 120 billion cum @3800 cum/sec recorded at Pasighat.
The International Centre for Integrated Mountain Development (ICIMOD) and other two international organizations in its research paper titled ‘The Himalayan Climate and Water Atlas: Impact of Climate Change on Water Resources in Five of Asia’s Major River Basins’ analyzed climate changing now and into the future, ‘with severe consequences for populations, both local and downstream of five major river basins– the Indus, Brahmaputra, Ganges, Salween and Mekong.Due to global warming, temperatures across Tibetan plateau will increase by about 1–2°C (in some places by up to 4–5°C) by 2050. Rainfall pattern will change with the monsoon expected to become longer and more erratic and violent. Glaciers will suffer substantial ice loss. Despite overall greater river flow projected, higher variability in river flows and more water in pre-monsoon months are expected, which will lead to a higher incidence of unexpected floods and droughts greatly impacting on the livelihood security and agriculture of river-dependent people.’
Historic Floods in the Siang River:
Himalayan floods are produced by breaches of landslide and glacially dammed lakes. Glacial lake outburst floods (GLOFs) are caused by the breaching or overflow of a lake formed due to damming by a glacier and landslide lake outburst floods (LLOFs) are formed by landslides. Many scientific researches revealed that Brahmaputra valley had been thrashed by several mega floods. In Tibet, during the Neogene period (1.7 million to 11700 years ago) several lakes were formed by dams created by the deposition of rocks and debris carried by glaciers. The volumes of the lakes were as high as 800 Million cubic meter (Mcum). The outbursts of these lakes generated mega floods in the Brahmaputra valley. Testing of flood deposits (silt etc) in the Brahmaputra valley indicate that they were originated mostly in Tibet and the floods evacuated huge volumes of sediment from the Tsangpo Gorge. Test data on fine grained sandy sequences found at 90 m above river bed level at Panging and Pasighat in Arunachal Pradesh indicate that at least one of these mega floods occurred between 8000 and 6000 years ago, another such event occurred 1200–1650 years ago, 18 mega floods of varying sizes occurred between 27000-18000 years ago and two mega floods between 27000-10000 years ago. The climate record from Mawmluh Cave, Meghalaya indicates a relatively warm and wet phase during which the mega floods occurred. Present global warming and climate change phenomenon may make the environment conducive for some more mega floods in the Brahmaputra valley in the near future.
Among the recent mega floods, a 60-meter high and 2.5-km wide dam was formed in Tibet by a major landslide that occurred on 9th April 2000. The dam breach caused floods that wreaked havoc in Arunachal Pradesh on 11th June 2000, claiming 30 lives and leaving more than 100 missing. Water level rose to 40m at Tuting. Most of the bridges were washed away and roads were damaged and more than 50,000 people in Arunachal Pradesh were left homeless by the floods. The extreme flood slowly lost its forte due to spreading in the plain areas before entering Assam in Sadiya.
Water colour of the Brahmaputra turned blackish due to high turbidity during November-December 2017.Dead fishes were seen floating at Pasighat due to contamination of the Siang river. Water of the tributaries eg Dibang, Lohit, Subansiri were clear which confirmed the root of pollution in Brahmaputra was Siang river only. At this time discharge of Brahmaputra was normally 6000 cum/sec at Pandu and average water entering India at Tuting is 1000 cum/sec which confirm high contamination in Siang river.A scientist from the National Centre for Biological Sciences, Bengaluru, using satellite imagery from NASA, USA reported that between 21- 27 October 2017, an avalanche releasing water, ice, rocks and other debris occurred on the Sendapu glacier which feeds into the Yarlung-Tsangpo river.
Pools of water could be seen on the glacier surface, indicating that melting ice may have caused mud and rocks to slip. This was the first indication of the Siang river being contaminated by natural reasons in early part of November 2017. Complicating further, a M6.4 earthquake struck on 17 November 2017 triggered widespread landslides on the Yarlung-Tsangpo river at 200 km upstream from Tuting. A satellite image five hours later showed several landslides and a 100 square-kilometre area of mountain slope entirely collapsed. Three natural rockslide dams formed on the river due to blockage by landslides and debris. It is only a matter of time before the natural dams burst and unleash a severe disaster along the Siang and Brahmaputra valley. However fortunately, the artificial dams instead of sudden break, slowly breached draining the water of the artificial lakes averting major disaster downstream in Arunachal Pradesh and Assam. Such incidences of abnormal flow variation and contamination of water observed in Siang river from time to time.
Chaina’s plan for development of water resources in Tibet:
As per reports, China’s development activities mainly construction of hydroelectric projects on the Tsangpo are primarily to raise the standard of living in Tibet, to manage fresh water scarcity and to support China’s goal of reaching a carbon emission peak before 2030 and carbon neutrality by 2060.
A map showing hydropower dams planned by China on Tsangpo in Tibet.
(Photo: The Diplomat, November 2019)
China had been secretive about plans to dam the Tsangpo and announced that a five-dam cascaded hydropower projects- Zangmu, Gyatsa, Zhongda, Jiexu and Langzhen would be initiated to the east of Lhasa. 116m high 510 MW Zangmu Dam on the mid-reaches of the Tsangpo, located in a gorge 140 km southeast of Lhasa, at an altitude of 3260 metres, started generating power in November 2014. 360MW Gyatsa (Jiacha) completed in August 2020 and Construction is under way for 560MWJiexu Dam.Close to Zangmu Dam, three more Dams 640 MW Dagu, 710MW Bayu and 800MW Zhongyu above the Great Bend, on a tributary known as the Yiwong river were in advance stage of planning.
Brahmaputra river at Great Band and sudden drop in 2.7 km elevation
before entering Arunachal Pradesh
China also plans its most-ambitious world’s largest hydropower project, a 60000 MW Moto Super mega-dam on the Brahmaputra’s barely explored Great Bend, a stunning canyon where the river drops fiercely over 2700m within 50 km stretch before it changes course towards India. It was also reported that China would divert the Tsangpo water from the project to its northern arid region. The announcement immediately sparked concerns among Indian analysts who suspected Beijing of harbouring ulterior geopolitical motives and asserted that the diversion could have negative environmental consequences, including reducing the flow of water into India as well as possibility of creating artificial floods.
560MW Jiexu Dam (photo-Dechen Palmo in The Diplomat)
Current status of the water disputes:
Hongzhou Zhang in WIREs Water 2015. doi: 10.1002/wat2.1123 stated that “the Brahmaputra river, shared by China, the upper riparian state and India, the middle riparian state is among the shared rivers where most tensions exist. This is due to three major reasons. First, China occupies over 50% of the Brahmaputra river basin area for which the potential impact of China’s activities on the Brahmaputra river is much bigger. Second, Brahmaputra river is a great importance to both India and China. For India, it accounts for nearly 30% of the freshwater resources and 40% of total hydropower potential of the country.
In case of China, while at national level, the Brahmaputra river’s role in the country’s total freshwater supply is quite limited but it is of great importance to Tibet. The Brahmaputra River is considered the birthplace of the Tibetan civilization and it plays a critical role in Tibet’s agricultural and energy sectors. Third, the Brahmaputra river is linked to Sino-Indian border disputes. This disputed area is called South Tibet in China and Arunachal Pradesh State in India which now controls the area. This disputed area occupies about an area of 83743 sq km and has a population of over 1.5 million people.”
China does have a track record of relying on mega-infrastructure projects such as world’s largest hydro project 22500MW Three Gorges Dam and South–North Water Diversion (SNWD) project to transfer 44.8 billion cubic meters of fresh water annually from the Yangtze river in southern China to the more arid and industrialized north through 1264km long three-canal systems to deal with its water challenges. In relation to transboundary river cooperation with neighbouring countries, China is one of the three countries, others being Turkey and Burundi, that voted against the 1997 UN Convention on the Law of the Non-Navigational Use of International Watercourses (UNWC). China is the largest producer of hydroelectricity in the world. Dams in Yunnan on the Mekong river have worried lower riparian countries Myanmar, Thailand, Laos, Cambodia and Vietnam, who have set up a joint inter-governmental Mekong River Commission (MRC) for joint management of shared water resources. However, China remains absent from the Commission.
India’s plan for hydropower development on Siang:
What really worries India the most is China’s water diversion plan at the Great Bend, which could let the Siang river run dry, thus threatening the survival of hundreds of millions in the downstream. Based on river basin data, it is easy to reach a conclusion that the potential impacts of Chinese flow diversion could be huge considering the fact that 50% of the river basin of Brahmaputra is in the Chinese territory. The capacity of a hydropower plant depends on the water availability and the height of flow to the turbines. With the scanty quantity of water availability, a 60000 MW project is possible in Tibet because of utilization of the tremendous drop of 2700m available at the Great Bend of the Brahmaputra. In the event of diversion of Siang river, the most affected areas will be 150 km reach of the river from Indo-China border to Pangin where major tributary Siyom river joins.
In sharp contrast with China’s rapid development activities on the Tsangpo, India has not utilize the water of Siang river till now, thus weakening its riparian rights in the International Forums for river water sharing. China’s proposed 60,000 MW dam in Medog could reduce the natural flow of water in the Siang in India during lean patches, or trigger “artificial floods” in monsoon which is a matter of concern to India. To counter any potential misadventures by China in the Brahmaputra river, India proposes a 11,000 MW hydro power project on the Siang river in Arunachal Pradesh’s Upper Siang district.The design of the Indian project includes a “buffer storage” of over 9 billion cubic meters of water during monsoonal flow.This could act as a reserve for water normally available from the Siangfor water security or protect downstream areas of Arunachal Pradesh and Assam against flood due to sudden releases of water from the Chinese mega project. Like in most the countries of the world, water scarcity already prevailed in other parts of India. Due to climate change, scientists predicted water scarcity in Northeast India in near future.
China’s response toward India’s complaints about China’s ravenous exploitation of the Tsangpo river has been mild. On the other hand, the CNA analysis & solutions in a study ‘Water Resources Competition of the Brahmaputra’ in May 2016 mentioned ‘China has concerns that; India’s dam building activities downstream could further strengthen New Delhi’s “actual control” over Arunachal Pradesh.’
Global warming that challenged the world irrespective of any geographical and political barriers is threatening the human existence. The global countries are unitedly fighting the eminent disaster.The carbon emissions from the thermal power plants are mostly responsible for global warming. India committed to achieve carbon neutrality by 2070 while all advance countries of the world committed to reach carbon neutrality by 2050 and China by 2060. Electric energy, a yardstick of development of a country,need transition of generation from thermal to renewable energy. Hydroelectricity being sustainable and cheap renewable energy, warranted for development of hydroelectric projects. Arunachal Pradesh alone has hydropower potential of 50328 MW, 40% of the country’s potential whereas only 1115 MW (2.21%) is operational.
International media reported, ‘Dam building has been an extremely slow and limited process in India, largely due to obtaining various statutory clearances especially environmental and forest clearances, civic opposition to some dam construction as well as financial constraints. This situation stands in stark contrast to the robust dam building on China’s portion of the upper Brahmaputra river. Despite India’s intention to build its own dams to manage water flows, the number of dams actually being built is extremely limited’.
The construction of China’s world largest, 23500MW Three Gorges Dam, 12 lakhs people were displaced without any resistance. But, opposition from displaced people for creation of reservoir in hydroelectric projects is a real challenge in India. No one in this world want to leave their own home and village where they are born and brought up with their families.
There had been significant movements in the past by the displaced people due to construction of Tehri Dam in Uttarakhand in 2001 and Sardar Sarovar Dam in Gujarat constructed on Narmada river that started in 1987 and fully completed in 2017. Idu Mishimi community of Dibang valley had opposed the 2880MW Dibang Multipurpose project for inadequate compensation for Project Affected People and probable environmental impacts of the project during 2007-2011.
However, with induction of the Right to Fair Compensation and Transparency in Land Acquisition, Rehabilitation and Resettlement Act, 2013, people are satisfied with the compensation packages and realised the benefits of the hydropower projects for local people as well as for the State.
Like all developmental works, hydroelectric projects may have adverse impacts on the environment. Environmental Protection Act 1986 and subsequent notifications from time to time, have taken care of the environmental impacts to be minimized during construction and operations of the hydroelectric projects. The Right to Fair Compensation and Transparency in Land Acquisition, Rehabilitation and Resettlement Act, 2013 (also called Land Acquisition Act, 2013) gives the fair compensation for land and rehabilitation and resettlement to the displaced persons. The Forest (Conservation) Act 1980 ensures conservation of forests and its resources by the compensatory afforestation for forest diversions so that the environment have minimum impact due to the construction of dams.
Wildlife Protection Act, 1972 amended in 2006 provides protection of the wild animals, birds and plant species to ensure environmental and ecological security. The Forest Rights Act (FRA) 2006 protects the rights of the forest dwelling tribal communities and other traditional forest dwellers to forest resources, on which these communities were dependant for a variety of needs, including livelihood, habitation and other socio-cultural needs. Manual for land acquisition in Arunachal Pradesh 2022 published the district wise and category wise land rates for land acquisition. Government should make the project affected people aware of the fair compensations, rehabilitation and resettlement provisions and compensatory afforestation program for minimum environment impact. After China (23841) and USA (9263), India ranked third globally with 5254 large dams in operation while 447 dams are under construction.
Most of these dams displaced millions of people. Overcoming the emotional factor of leaving ancestral houses, villages, towns to resettle in new habitations, the project affected peopleought to cooperate with the government in dam building for all round development of the State and the Country.