State of Rivers in Assam:Challenges & Need of Sustainable Management for Ecological& Human Wellbeing

By Dr. Partha Jyoti Das


Rivers should not be considered only as a water carrying channel meant for optimum exploitation for hydropower, irrigation and navigation. We must change our attitude towards rivers as a resource meant only to be exploited for economic benefit...


The Brahmaputra near Guwahati.

Photo: Udayan Borthakur



Why are rivers important?


Rivers are natural water ways that carry flowing water and sediment, form floodplains, make valleys, gorges and deltas before merging with seas and oceans. Rivers are a part of the natural hydrological cycle and they act as conduits for driving global bio-geo-chemical cycles. Rivers act as drainage channels to carry and distribute water, sediment and nutrients to the valleys. Deltas are formed and maintained by sediment delivered by rivers. River deltas are among the most important agricultural regions of the world that support and feed about 500 million (about 6.7% of global population) poor and vulnerable people.


Draining nearly 75% of the earth's land surface, rivers are lifelines for sustenance of human societies and natural ecosystems. Human civilizations dawned and flourished on riverbanks because rivers facilitate soil fertility, agriculture, irrigation, navigational transport, congenial climate and diffusion of culture. It is because of the ecohydrological functions and services provided by rivers and riparian ecosystems that enable people to get and produce food, water and livelihoods. Rivers provide food and habitat for many aquatic organisms such as fish, dolphin, herpetofauna and aquatic vegetation.


River Bhogdoi in Jorhat district, Assam, a tributary to the Brahmaputra.

Photo: Udayan Borthakur


Rivers are central to driving the economic engine in many countries. Water derived from rivers and other sources enriched by rivers (such as ground water, wetland, lake) is the single major source for ensuring water security for drinking and other human purposes, irrigation, agriculture, industry and sanitation. Rivers irrigate 190 million hectares of land, which is about 62 percent of all irrigated land of the world that accounts for 40 percent of global food production. Thus, rivers directly support approximately a quarter of global food production through irrigation. Rivers provide us energy from hydropower plants which is about 17 percent of global electricity generation (WWF, 2018).


Wetland in Nimati, Jorhat district, enriched by the Brahmaputra

Photo: Udayan Borthakur


At least 12 million tons (about 12 percent of the world’s fish catch) of freshwater fish, the only low-cost source of nutrition to low-income communities and a booster of local economy in most developing countries, come directly from rivers. River fisheries provide fish-based nutrition to about 160 million people and livelihoods for nearly 60 million people, with 55 percent of those being women (WWF, 2018).


Rivers are part and parcel of religion and culture of human societies. They find a place in folklore, music, literature, mythology and history of nations and communities all over the world. There are many religious and cultural rituals and practices among indigenous peoples of the world where rivers play a central role. Many rivers are considered as sacred by local people. Rivers also influence the social norms and moors as well as processes of social transformation and change.


Rivers also have political and strategic importance especially in case of transboundary water courses and when rivers define political boundaries between countries and within a country. At least 58, 588 km (23%) of the world's interior (non-coastal) national borders, 199,922 km (17%) of the world's interior state/province borders, and 459,459 km (12%) of the world's interior local-level political borders are marked by large rivers (Popelkaa and Smith, 2020).


River Manas, a transboundary river between Bhutan and India

Photo: Udayan Borthakur


Why are rivers threatened?


Notwithstanding their multiple services and values, rivers are globally one of the most threatened natural entities at present. This is mainly because there is lack of understanding in public in general about the life sustaining services and values of rivers. People’s age-old knowledge and admiration for rivers are now limited to a small rural population. Development policy makers are generally not sensitive to the crying need of protecting rivers, riverfronts and flood plains. Problems created to rivers are attended mostly as stand-alone issues without a holistic comprehension of rivers and their intricate relationship with various aspects of human life, nature, agriculture and livelihood.


Many of the world’s rivers are polluted, degraded, marginalized and endangered. Pollution from solid wastes, liquid effluents and sewage have rendered the waters of many rivers unfit for human use. Many small rivers are retarded in flow by the burden of plastic materials that litter the channels for long stretches. Deforestation in watersheds trigger more soil erosion and increase sediment load in rivers causing turbidity and also leading to irregular erosion and deposition patterns. Invasive aquatic species are harmful to the natural hydro-biological properties and biodiversity that rivers possess.



The Bharalu (in Guwahati), that was once a pristine river, has degenerated to filthy drain

Photo: Partha Jyoti Das


Hydraulic structures like dams, embankments and barrages have fragmented longitudinal and lateral connectivity of rivers obstructing natural flows, transport of nutrient carrying sediments and movement of fish and other aquatic organisms. Many rivers go dry seasonally and no longer flow to seas because of overextraction of water for irrigation and hydropower production. Just over one-third (37%) of the world’s 246 longest rivers have remained free-flowing at present. Dams and reservoirs are drastically reducing the diverse benefits that healthy rivers provide to people and nature across the globe. Only 21 of the world's 91 rivers longer than 1,000 km that originally flowed to the ocean still retain a direct connection from source to sea (Grill G, et al.,2019).


The flood plains world over have been abused and encroached with unpragmatic interventions like intensive settlement, agriculture, construction, pisciculture and commercial cash-cropping resulting in degeneration and death of wetlands, traditional farming in low lying areas, and hydrological connectivity. Fragmented flood plains with degraded and desiccated wetlands lose their capacity to produce food, store water and moderate floods.


Excessive sand mining and industrial pollution in the Kulsi river are grave threats for the survival of the endangered Gangetic River Dolphin.

Photos: Udayan Borthakur


According to the UNEP, pathogen induced pollution from untreated sewage has affected about half of Asia’s rivers, around a quarter in Latin America and around 10-25% in Africa. About 3.4 million people die each year from diseases associated with pathogens in water, like cholera, typhoid, infectious hepatitis, polio, cryptosporidiosis, ascariasis and diarrhoeal diseases. About 134 million people in Asia, 164 million in Africa and 25 million in Latin America are at risk of infection from these diseases. Organic pollution of rivers and other surface water bodies is major cause of harm to fresh water fisheries that provide humans with the sixth most important source of animal protein. River fisheries, in developing countries, employ 21 million fishermen and create 38.5 million related jobs. Globally, almost 80 per cent of wastewater goes into water bodies with serious consequences for health and the environment resulting death of about 1.8 million people every year from water-related diseases(UNEP, 2016).


How are rivers doing in India?


Recently the Central Pollution Control Board has identified 351 polluted river stretches across the country (CPCB, 2018). More than 60% of the country’s sewage is released into the streams and rivers untreated. Consequently, half of the rivers in the country are now polluted with the Ganga, Sabarmati and Yamuna being the filthiest of them. Reason why India stands a poor 120th among 122 countries in the world on the Water Quality Index based on the availability of clean and sufficient water[1].


As many as 60 of the polluted stretched are located in northeast India where 44 are in Assam, 9 in Manipur and 7 in Meghalaya. River pollution in NE India is caused mainly by discharge of untreated industrial and mining effluent and dumping of solid waste from domestic and municipal sources. Unscientific and indiscriminate coal mining is specially responsible for water pollution in rivers in Meghalaya, Assam and Nagaland(CPCB, 2018).



Top Photo: Many parts of the river Kolong in Nagaon DIstrict are suffering from eutrophication leading to its degradation due to lack of flowing water.

Bottom Photo: Kolong river under heavy encroachment pressure.

Photo: Partha Jyoti Das



State of rivers in Assam: Concerns and issues


Assam is a land of perennial and vibrant rivers. With more than 125 prominent (major, medium, small) rivers flowing in the state, which contribute to either the Brahmaputra or the Barak, the density of rivers is so high that we can call it a riverine land. The Brahmaputra has 41 major tributaries inside Assam out of which 26 are flowing from the north (right bank) and 16 from the south (left bank). The Barak also has eight important tributaries within Assam.


People’s lives in the state are intricately entwined with rivers so much so that rivers have become an integral part of religious rituals, cultural heritage and social dynamics. The Brahmaputra and the Barak, the two large rivers and their tributaries that drain the state are responsible for laying out the fertile Brahmaputra and the Barak Valleys. The major livelihoods of people such as agriculture, pisciculture, dairy, navigation, water transport and trade are dependent on rivers. Rivers are held as sacred and vital for people’s culture and religious rituals throughout the state, especially among the indigenous communities.


Yet, people in general now-a-days consider rivers as sources of their sorrow mainly because of the disasters triggered by flood and bank erosion and suffering caused to riparian people. It is to be remembered that flooding and erosive action of rivers are their natural functions.

However, due to the changing catchment conditions of upstream areas, flaws in river management policies and practices (especially in river training and structural interventions on rivers), as well as climate change, floods and erosion have become more frequent, intense and damaging. Indiscriminate and unscientific sand mining is another reason why many of our river channels have undergone ecohydrological degradation.


Dams that have been built on our rivers either within the state or in neighboring states have delivered both benefits and incurred costs. Although dams have contributed to energy security in a limited sense, they have also fragmented riverine habitats causing loss of aquatic flora, fauna and biodiversity. Flash floods caused by sudden and mostly unwarned release of monsoon flows from upstream areas have caused large scale destruction, loss of human lives and suffering of people. Such dam-induce flooding from the hydro projects on the Ranganadi (Yazali, Arunachal Pradesh), Kopili (Umrangchu, Assam) and Dayang (Nagaland) are now common in Assam.



The river Ranganadi drastically dries up in the winter season due to reduced and fragmented flow caused by reservior operation of the Ranganadi Hydel Power Project located in Yazali in Arunachal Pradesh

Photo: Partha Jyoti Das


There is a general perception that rivers of Assam do not have any serious problem of pollution since there are not too many industries, factories or manufacturing units along the rivers. This is no longer true. Many of our rivers are polluted, a number of them severely contaminated in some stretches that lie mainly in and around urban centers.


The Central Pollution Control Board (CPCB), in its assessment done in 2018 identified 44 stretches of rivers and wetlands and water bodies of Assam as polluted based on Biological Oxygen Demand (BOD) level in rivers, which is a key indicator of organic pollution. As per the CPCB report, out of a total of 351 polluted river stretches and water bodies of the entire country, Assam has 44 numbers of contaminated water areas, the second maximum number after Maharashtra that has 53 stretches (CPCB, 2018). Fecal coliform count, which indicates presence of pathogens is also another important factor of pollution of surface water bodies in Assam. In the year 2015, number of pollutes stretches were 28 in Assam (CPCB, 2015).


There are 30 rivers in Assam having polluted stretches distributed over 19 districts. These are:

(1)Bharalu (Kamrup Metropolitan), (2) Digboi (Tinsukia), (3) Panchnoi (Udalguri), (4) Brahmaputra (Dibrugarh, Jorhat, Sonitpur, Kamrup Metropolitan and Kamrup), (5) Kharsang (Tinsukia), (6) Pagladiya (Nalbari), (7) Barak (Cachar), (8) Buroi (Biswanath), (9) Bega (Darrang), (10) Beki (Barpeta), (11) Bhogdoi (Jorhat), (12) Boginadi (Lakhimpur), (13) Burhidihing (Tinsukia), (14) Dhansiri (Golaghat), (15) Dikhow (Sibsagar), (16) Dikrong (Lakhimpur), (17) Disang (Sibsagar), (18) Gabharu (Sonitpur), (19) Jia Bharali (Sonitpur), (20) Janji(Jorhat and Sibsagar), (21) Kolong(Nagaon), (22) Kopili(Nagaon), (23) Kiling(Morigaon), (24) Kohora(Golaghat), (25) Kulsi(Kamrup), (26) Mora Bharali(Sonitpur), (27) Puthimari(Kamrup), (28) Ranganadi (Lakhimpur), (29) Sonkosh(Dhubri) and (30) Sonai(Cachar).