Brahmaputra River
1. Introduction
The profusion of rivers in the northeast India is simply unparalleled (Fig 1). There two major
rivers Brahmaputra and Barak have been joined by tributaries in abundance – small and big, the
bigger tributaries often surpassing some prime main stem rivers of other states of the country. On
the northern side, the great river Brahmaputra, and on the southern side, the Barak River flow
across the state of Assam. Both the rivers have been separated by the Borail range. Rather
ironically, they are well known primarily due to causing havoc through natural disaster like flood
and river bank erosion every year. Plentiful tributaries of both the rivers originate from the hills,
which are often outside the boundary of the host state. Interestingly, both Brahmaputra and
Barak, after flowing through the length of the state, merges with other rivers at Bangladesh, to
finally fall into the Bay of Bengal. On the other hands, both the rivers, notwithstanding their
accompanying hydro disasters in the corresponding Brahmaputra valley and the Barak valley
(also known as Surma valley) during monsoon, makes the floodplains fertile by the endowment
of fine nutrient laden silt load.
1.1 The Brahmaputra River System
The Brahmaputra is known in different names along its course. Originating in the east of Kailash
Mountain, it flows east of the Mansarovar lake along the Indus Tsangpo sutures known as
Tsangpo. Around Namcha Barwa, it changes course to enter India as the Siang. It debouches in
the Assam Plain downstream of Pasighat and flows in WWS direction till Dhubri where it turns
southward into Bangladesh.The river is known as the Brahmaputra along its traverse from
Dibrugarh to Dhubri and as the Jamuna in the Bangladesh. The Brahmaputra receives many
tributaries all along its course of about 2800 km. These include the Lhasa He and the Nyang Qu
in Tibet; the Parlung Tsangpo in the eastern syntaxis; the Dibang and the Lohit from the Mishmi
Hills; the Subansiri, the Ranganadi, the Jia Bhareli, the Puthimari, the Manas and the Tipkai
from the southern slope of the Himalaya and the Burhi Dihing, the Dhansiri and the Kopili from
the Indo-Burmese Ranges. The total drainage area of the Brahmaputra river system from its
origin to its mouth is 630000 km2, of which about a third,220000 km2
, lie in Tibet. It drains
an area of 200000 km2 in the Assam and the Bangladesh plains and 120000 km2 in the
Himalaya. The two eastern tributaries, the Lohit and the Dibang flowing through the Mishmi
Hills together have a drainage area50000 km2
(Goswami, 1985)
The name Brahmaputra finds its mention in Kalika Purana, a mythological text of Hinduism,
which is believed to have been written around 10th Century A.D. (Dutta, 2001). The SantanuAmogha-Parasurama myth finds place here and explains the origin of the river (Dutta, 2001).
The famous King Sagar, on seeing the river, summoned a sage, Aubadhya, who used his fecund
imagination to enlighten the king with a story tracing the origin of the River to Lord Brahma, the
God of creation in Hindu religion. Later, it is believed that sage Parasurama cleaved the bank of
the Brahmakunda to cause the Brahmaputra to flow as a river and inundate the region of
Kamrupa or present day Assam (Dutta, 2001).
Puranic texts had accounted the Kunda, the origin of the river as somewhere near Mount
Kailash. But accounts of the natives, while agreeing that the river originated in the Kunda,
recounted the site to be somewhere east-north-east of Assam, in a range of mountains beyond
Nara, meaning the boundary of Assam and Burma (Dutta, 2001).
Investigations of the Indian side of the eastern Himalaya started in 1824 when Lt Wilcox
surveyed a number of rivers, including the Dihang and Lohit, which converged and formed the
Brahmaputra at Sadiya in Assam. Both he and Pemberton, who had returned from an
appointment in Bhutan, had obtained local knowledge that suggested that the Tsangpo and
Dihang was the same river.
In the padma Purana, there is a mythological story about the birth of river Louhitya. According to one
mythology, Amogha, wife of Sage Shantanu, had a child by Brahma, the creator of the Universe.
The child took the form of water. Shantanu placed the child right in the middle of the four great
mountains – Kailash, Gandhamadana, Jarudhi and Sambwartakka. Susequently the child grew
into the lake of Brahmakunda. Later Lord Parashurama, one of the ten incarnations of Lord
Vishnu, got rid of his sin of beheading his own mother Renuka on strict order of his father
Yamadagni with an axe by taking bath subsequently in Brahmakunda and made a passage for
the Kund to come out as the river Brahmaputra by digging the bank of the Kund. It is believed
that Parashuram Kunda near Tezu in Arunachal Pradesh is the spot where the axe dropped from
the hand of Parashurama
Investigations of the Indian side of the eastern Himalaya started in 1824 when Lt Wilcox
surveyed a number of rivers, including the Dihang and Lohit, which converged and formed the
Brahmaputra at Sadiya in Assam. Both he and Pemberton, who had returned from an
appointment in Bhutan, had obtained local knowledge that suggested that the Tsangpo and
Dihang was the same river.
In the 16th century AD, scripture Kalika Purana, the Brahmaputra river is mentioned as Amogha
Garbhasambhuta. During the auspicious occasion of Ashokastami, the mantra recited during
the holy dip, amogha garbhasambhuta and louhitya both meant the river Brahmaputra.
Brahmaputra mahabhaga shantanu kulanandana
Amogha garbhasambhuta papang lohitya me hara
(O Brahmaputra, I salute thee! O son of Santanu, I salute thee! O Lauhitya form, remove all my
sins from previous three births!) (Dutta 2005)
Darjeeling born Sikkimese named Kinthup or K.P. in British records who, spent four years between 1879 and 1882 vidicated these findings (Bulletin of the American Geographical Society, 1915). In 1879, the Survey of India sent a Lama in the Sikkim monastery, known as G.M.N in the official records, to Tibet, to solve the mystery of the Tsangpo i.e. solve the problem of its origin (Bulletin of the American Geographical Society, 1915). They followed the Tsangpo from Arunachal Pradesh eastwards up to the western end of the big gorge through the Himalayas and then returned (Bulletin of the American Geographical Society, 1915). In 1880 a Chinese Lama was employed to continue G.M.N’s exploration of the Tsangpo and Kinthup was employed to accompany him. They were instructed to throw logs into the Tsangpo at the lowest point reached in their travels and that watchers have been placed at the point where Dihang debouched into Assam (Bulletin of the American Geographical Society, 1915). The two reached Tibet and travelled further upstream of the Tsangpo to reach Tong-juk Dzong in May 1881. Kinthup returned to India in November 1884. Until two years from his return, his account was not taken and translated. It was finally Colonel Tanner, who compiled a sketch map of the Dihang basin from Kinthup’s narrative. Kinthup was not a trained explorer and in absence of any instruments, notebooks etc., he had to rely on his memory in giving the account of his travel, extending up to four years and covering a large area (Bulletin of the American Geographical Society, 1915). The report ‘Explorations of the NorthEast Frontier during 1911-12-13’ by Colonel S.G. Burrand examined Kinthup’s work in the light of surveys reported by the Abor expedition, and found Kinthup’s accuracy of names striking (Bulletin of the American Geographical Society, 1915). Additional information about the Tsangpo was furnished by Kishen Singh (A.K.) at the end of his memorable four-year journey through Central Asia and his return by the gorge country of south-eastern Tibet (Ward 2000). It was in a volume by Swami Pranavananda that the source of the Brahmaputra or Yarlung was traced as Chema-Yungdung glacier (Pranavananda 1949). Only recently, in 2011 scientists from Chinese Academy of Sciences found that the origin of the Brahmaputra is the Angsi Glacier.
1.3 Water, People, Literature, Art and Culture
The Tsangpo-Brahmaputra is considered sacred in India, Bhutan and Tibet by the population
characterized by multiplicity of cultures. The literal meaning of its Tibetian name, Tsangpo, is
the Purifier (Dutta 2001). In Hindu mythology, the river is considered to be sacred and thousands
of people take a dip in Brahmaputra during the festival Ashok Astami. Though, there are Aryan
myths about the creation of the river, the tribes that inhabit in the Himalayan foothills have no
such folk-myths regarding the origin of Brahmaputra in their folk-mythology (Dutta 2001).
However, there do exist, folk-myths about the fabulous origin of the tributaries like the KanyakBhairavi myth with regards to the Jia Bharali tributary of the Brahmaputra or about Subansiri
river among the Mishings who call the river Abanari (Singh 1995; Dutta 2001). Many tribes like
the Dimasa also derive their names from river or water. The Dimasa tribe call themselves sons of
the big river (Di- river, Ma-big, Sa-son). Similarly, the Hill Miri tribe which inhabits Lower Subansiri and Upper Subansiri districts of Arunachal Pradesh derives its name from water or
river (Singh 1995). Dimasa tribe of Assam consider themselves to be the son of river
Brahmaputra, after they settled down in the valley. Dima means big and sa means son. Earlier
Dimasa’s were known as Badosa, a constituent of the Bodo ethnic tribe. Another community
known as Mishing is the amalgamation of two words ‘Mi’ which means man and ‘shing’ means
water.
A frontier region, of bewildering diversity with numerous ethnic tribes residing, speaking different dialects and following diverse cultural practices, they have varied customs, most of which are invariably linked to river and forest. The Mishings claim to have come down to the banks of the Brahmaputra and spread over the banks of Subansiri and Dhansiri. The legend has mentioned their fondness for river banks, as settlement sites. Fishing is indispensible to them (Singh 2003). Further, almost all the tribes in the Arunachal Pradesh relate the river with spirits, natural calamities, and agriculture. Almost all the festivals among the tribes in the Siang-DihangBrahmaputra basin have agro-religious significance. Where fishing is the major occupation, like among the Jhalo-Malo group in Assam who reside in Barpeta and Goalpara districts, dependence on water resources is also reflected in their cultures.
The original word for ‘Jhalo’ is ‘julla’ meaning ‘water’ and ‘malo’ meaning malla infantry, their
original occupation being fishing and infantry (Singh 2003).
The Sonowal Kochari tribe of upper Assam celebrates an agricultural ritual, twice or trices a year
known as “Lakhimi Tola Sobah”. The ritual is river centred, where through religious procession
and music, people gather at river ghat, and specially chosen person delves into the river water to
catch fish with a Jakoi (fish catching equipment). If they catch fish, it is considered as Lakshmi’s
blessings to the village
“Luitor paaror deka bondhu tumar tulona nai, Jiyai thokar jujot naamisa mrityu xopot
khai” (Young friends from the bank of river Luit, you are unparalled, you have sworn by
death to fight for your motherland)
In the field of fine arts, most of the landscape artists of Assam like Benu Mishra, Nilpaban
Barua, have done vast numbers of paintings on river Brahmaputra and life on the river bank.
Some of the famous paintings are Shankardeva and Brahmaputra by Mabegum Pasa, Tibetan
Painting on Yarlang Tsangpo by Susan Mayclin Stephenson, Brahmaputra by Nicholas Roerich,
Bank of River Brahmaputra by Anupam Saikia,
Apart from numerous articles in Newspapers, Magazines and Academic Journals, a number of
important books published on the Brahmaputra that are worth mentioning are as follows:
Axomor Nod nadi by Jogendra Nath Sharma, Brahmaputra and the Assam Valley by Ranjit
Biswas, River Dog, A journey down the Brahmaputra by Mark Shand, Brian on the Brahmaputra
by David Fletcher, Water war in South East Asia, Brahmaputra, Dam and Diversion, Colonel
Puneet Raina (Retd), The Brahmaputra by Arup Kumar Dutta, The Brahmaputra Basin water
resources, Edited by Vijay Singh, Nayan Sharma, C. Shekhar, P. Ojha, Tales from River
Brahmaputra by Tiziana Baldizzone and Gianni Baldizzone, The last River:the tragic race for
Shangri-La by Todd Balf, Sands of the Brahmaputra River Basin by Zaman Mohammad Nazim,
Rahman Aminur and Biswas Pradip Kumar
1.4 Physiography
The basin is categorized into three different physiographic zones respond differently to the
anticipated climate change. TP covers 44.4% of the basin, with elevations of 3,500m a.s.l and
above, whereas HB covers 28.6% of the basin with elevations ranging from 100m to 3,500m
a.s.l. The area with an elevation of less than 100m a.s.l. is considered as FP and comprises about
27% of the entire basin(Immerzeel, 2008).
Further the physiography of Assam is divided into three broad geographic units 1:
1. The lower and central Assam hills, known as the Shillong Plateau : The lower and central
Assam range which includes, the Garo, Khasi, Jaintia and the outlying Mikir hills are in
reality a plateau or table-land. The general height of the plateau ranges between 3,000ft and
6,000ft. The Khasi and Jaintia hill portion of the plateau are comparatively higher and flatter
than the Garo and Mikir hills on the west and northeast. The highest peak of the plateau is the
Shillong peak (6450 ft)
2. The Barail ranges and the low hilly terrains of Mizo hills : The lofty Barail ranges, also
known as the North Cachar hills, are separated from the Shillong plateau on the Northwest by
a system of narrow valleys. Tectonically, the Barails form a south westerly extension of the
mountain chain of Nagaland and western Burma. It is this chain of mountain that separates
the valley of Irrawaddy and Chindwin of Burma from the valley of Brahmaputra and the
Meghna. The Patkai, Naga and Manipur hills and the Mizo hills form part of this great
mountain system. The Mizo hills consist of a belt of North-South trending ridges with
intricate valleys, with an average height of 3,000ft
3. The Alluvial valley of Brahmaputra, Dhansiri and the Barak River : The alluvial plains
of Assam consist of two distinct parts:
a) The valley of the Brahmaputra and its tributaries and
b) The Barak valley
These are separated from each other by the watershed of the Shillong plateau and the Barail
ranges. The Brahmaputra valley separates the sub-Himalayan foothills from the Shillong
plateau and the Patkai-Naga hill ranges. The Mizo hills and the Barail ranges die out towards
the west and south west into the plains of Cachar, which is a part of Surma-Kusiyara valley.
1.5 Geomorphology
The bank of the Brahmaputra, for the most part, is extremely unstable. Bank failures are rampant
and are a result of frequently changing flows, coupled with the fragile geology of the river banks.
Moderately high return flows cause large scale slumping of banks. High moisture content and
low proportion of clay make the banks highly susceptible to erosion (Goswami, 2010). The
drastic channel configuration changes undergone by the river speaks of its dynamics and of the
enormous amount of erosion caused by it Braiding indices of the Brahmaputra at Dibrugarh and Guwahati are 5.3 and 6.7 respectively.
Excessive sediment transport, erratic flows, erosion prone river banks, and long term aggradation
of the channel are the primary factors driving the braiding phenomenon. Most of the channel bars
in the Brahmaputra are highly transient in nature, being submerged during summer flows, and
visible during lean flows in winter months, especially January. Bed forms in the river channel
range from small sized ripples to large scale dunes Estimation of the amounts of aggradation and degradation in the Brahmaputra with more sound
values of average annual sediment load from WAPCOS 1993 report suggests that as a whole, the
Assam section of the river registered a net bed-level aggradation of about 6.39 cm, i.e. a difference of about 9.61 cm from the value estimated by Goswami, 1985. This reveals that the
net aggradation undergone by the river has decreased in recent times, justifying the tendency of
the river to restore itself to its previous state of equilibrium The Brahmaputra basin in Assam comprises three major categories of geomorphic units—
depositional, denudational and structural. Only the depositional unit, which is of fluvial origin,
includes floodplain deposits, younger alluvial plains, older alluvial plains, upper piedmont plain,
lower piedmont plain and valley-fill areas. The channel of the river Brahmaputra undergoes
changes in response to variations in the flow regime, pattern of sediment transport, and
neotectonics. Continuous shifting of the thalweg from one location to another takes place within
the bank lines and the river exhibits a braided channel pattern with temporal changes in bank line
location as well as channel configuration. The major north-bank tributaries, such as the
Subansiri, Jia Brarali, Manas, Sonkosh, exhibit partially braiding character at present but they
were meandering rivers prior to the great earthquake of 1950. The characteristic features of the
Brahmaputra floodplain are anabranches, locally known as Suti or Sota.
1.6 Climate of the valley
The climate of the Brahmaputra valley cannot perhaps be discussed separately from the climate
of NE India. The climate of NE India is distinct from the rest of India due to special features
such as orography, the alternating pressure cells of NE India and that of the Bay of Bengal, the
predominant maritime tropical air mass from Bay of Bengal followed by south Indian ocean, the
roving periodic western disturbances and the local mountain and valley winds (Borthakur 2004).
The region belongs to the transition zone of tropic and extra-tropic and as a consequence
experiences westerly moving tropical weather systems like lows, depressions and cyclonic
storms during pre-monsoon, monsoon and post-monsoon, as well as extra-tropical easterly
moving weather systems like western disturbances in winter (Pathak, 2000). Though depression,
deep depression and cyclonic circulation are the potent rain bearing weather systems causing
widespread rainfall in India, their direct entry during monsoon to NE India is very rare (Pathak
2000). However, re-curvature of monsoon depression after reaching Bihar plateau and adjoining
area due to westerly trough is common during monsoon season. On re-curvature, the rain bearing
southwest sector of depression gets changed to NE sector (Pathak, 2000). Frequent major floods
occur during monsoon season in the Brahmaputra valley caused by heavy rainfall associated with ‘Break’ monsoon situations or re-curving monsoon depressions from the Bay of Bengal (Dhar
and Nandargi 2000). The break monsoon occurs when the axis of the seasonal monsoon trough
shifts northwards from its normal position and lies close to the foothills of the Himalayas (Dhar
and Nandargi 2003). These two particular meteorological situations are responsible for causing
heavy rainfall on about 65% of occasions over the north eastern and central Himalayas and their
adjoining plain areas (Dhar et al. 1984), while the rest of the country reels under drought
condition with low or no rain The Brahmaputra valley including adjacent eastern Gangetic plains gets affected by severe
thunderstorms during pre-monsoon months, in particular during April–May. The valley gets a
good amount of rain (about 25% of annual total) falling during this season due to “Nor’westers”
which makes the climate cool even during spring. In contrast, there is very little rainfall from
March to May in the rest of northern India (Das 1992). This occasional rain in the valley is
highly significant for the cultivation of jute, autumn rice and for the budding of tea plants.
Thunderstorm activity over the Brahmaputra valley is highest in the country, which produces
heavy rain showers, lightening, thunder, hail-storms, dust-storms, surface wind squalls and
tornadoes (DST 2005) often causing extensive damage to winter wheat, summer paddy and tea
crop. During winter, chilly wind from the Tibetan region is obstructed by the Himalayas and as a
result, the valley is protected from unbearable cold. Winter is the driest period in the valley.
Local circulations and western disturbances bring some rainfall even during the winter season (Atri and Tyagi 2010)
The Brahmaputra valley receives a mean annual rainfall of 2,293 mm (Deka et al. 2013).
Monsoon rains from June to September account for 60 – 70 % of the annual rainfall in the valley
while the pre-monsoon season from March to May produces 20 – 25 % of the annual rainfall.
Mirza et al. (1998) studied the changes of rainfall over Ganges, Brahmaputra and Meghna basins
and found that annual rainfall over the north Assam sub-division (part of the Brahmaputra
valley) showed an increasing trend during the study period of 1901–1981. Sen Roy and Balling
(2004) found decline in annual precipitation in the NE India. Deka et al (2013) noted a
downward trend in rainfall during monsoon and post-monsoon seasons in the Brahmaputra basin
in the state of Assam, NE India for the period 1901-2010; this trend was most pronounced in the
last 30 years. Poor irrigation coverage and higher degree of probable rainfall fluctuations due to global warming requires better knowledge of spatiotemporal rainfall distribution for planning
agricultural operations for optimal yield. However, information of spatiotemporal variations of
rainfall over the Brahmaputra valley has been scarce. The present study reports on the outcome
of analysis of rainfall data for different parts of the Brahmaputra valley during the last 110 years.
This is definitely instrumental in terms of sound understanding of spatial and temporal variations
of monthly, seasonal and annual rainfall which will definitely help in evolving new strategies for
management of food security and water resource in the valley
2. Major tributaries and sub-tributaries of the Brahmaputra Basin
Originating from Kailash ranges of the Himalayas at an elevation of about 5150m, river
Brahmaputra flows through Tibet (China), India and Bangladesh for about 2900m and joins the
Ganga. The river receives a number of tributaries at the north and south banks, in the catchment
area within India. The major tributaries and sub tributaries of the Brahmaputra are as follows:
Major North and South Bank Tributaries and sub-tributaries of Brahmaputra
South Bank Tributaries
Laikajan, Dibru, Maijan, Burhidihing, Disang, Dikhow, janji, Bhogdoi, Kakodonga,
Gelabil, Dhansiri, Dipholu, Kolong, Pokonia, Basistha, Bahini, Kulsi, Krishnai, Jinari,
Deosila, Jinjiram
Sub Tributaries
Dumduma ,Dangori ,Dhola,Namsik, Tirap, Namdang, Dirak, Namsang, Tipling, Tingrai,
Disam, Sesa, Timon, Taokak, Sofrai, Diroi, Dimou, Mudijan, Kakojan, Teok, Ghiladhari,
Kasojan, Dholi, Doiyang, Nambor, Deopani, Rengma, Kolioni, Nanai, Diju, Misa, Haria,
Rani, Dudhnoi, Sonai
North Bank Tributaries
Jiabharali, Sadharu, Burigang, Borgang, Jinjia, Brahmajan, Bihali, Puthimari, Champamati,
Gaurang, Dhansiri N, Pagladia, Beki, Manas, Jiadhol, Subansiri, Belsiri, Barnadi, Nanoi,
Noanadi, Tipkai, Dikrong
Sub Tributaries
Sarikoria, Gai, Moridhol, Kanibeel, Sila, Dangdhora, Ghagor, Kakoi, Bogi nadi, Ranga nai,
Singora, Solengi, Kukurajan, Begoti, Sadharu, Bor Dikorai, Mansari, Garhjuli, Digholjuli,
Moinajuli, Rangagora, Mora Dhansiri, Beganai
