This research note highlights the existing issues related to the sedimentation problem in one of the largest rivers in India, i.e. the Brahmaputra River. It draws attention to various issues related to the river and how the gaps in the existing policies are causing a problem in resolving these issues promptly. The issues which are discussed in this note is, at times, highlighted by various other eminent authors who have a great understanding of the river. Further, it also casts light on the management measures taken by China to resolve a similar issue of sedimentation in their Yellow River. The idea of bringing the Yellow River into the picture was to establish a global to Indian perspective and to understand what learning we can get to resolve the issues related to the Brahmaputra River. It discusses and recommends an establishment of an effective and integrated river body system or institution which is exclusively responsible for taking care of the river in a much more effective by addressing the gaps in current policies.
- The Brahmaputra rises from Angsi glacier in the Tibetan Himalayas and traverses almost 2900 km to the sea. 1600 km in China, 900 km in India and 400 km in Bangladesh. Avg. depth is 125 ft and avg. width is 9.5 km. It supports the lives of more than 190 million people in China, India, and Bangladesh. For India, it accounts for 30% of the total water resources and above 44% of the total hydropower potential
- Since the Tibetan plateau is 4 to 5 km above the sea level and when river flows from such a height then it erodes a lot of loose soil and rocks along with it courtesy of high speed and it results in sedimentation. The sedimentation problem with the Brahmaputra is one of the major concerns, and it has been a cause of various roadblocks in the development of the region.
Key Sedimentation Related Issues Concerning the River
- Channel morphology and changes in the river: The excess sedimentation in the river is the main cause of the rising of riverbeds. It thus plays an instrumental role in deciding the flow of the river and often is the reason behind the change in the direction of the river, which has happened in past.
- Erosion in Brahmaputra River: When the Brahmaputra River enters India, it flows at high speed and possesses a large volume of water which becomes a reason for the erosion of the region through which it is flowing. This heavy erosion later becomes a cause of sedimentation.
- Floods in the river: Floods have become a regular phenomenon in the Brahmaputra River. The rising of the riverbed, which happens because of sedimentation, is believed to be in some way or the other related to the devastation that is caused by floods.
Sediment Management Measures
- Sediment yield reduction
- Erosion management measures are implemented in the upstream regions to reduce the quantity of sediment getting carried by the river, and it helps in slowing the rate of sedimentation.
- Various attempts are made to reduce the sediment yield through changes in land use like afforestation and altering agricultural practices to emphasize on erosion control approach.
- The yield reduction method also helps in maintaining soil productivity and reduces storm runoff.
- It is one of the most environment friendly and sustainable methods of dealing with the excessive sedimentation problem.
- In this method, the riverbed is dug, and sediments are trapped in it where the dimension of the trap depends on factors like speed of the water, type and size of the sediment carried by the river.
- Prior findings need to be extracted regarding the type of sediment in the river so as to make this method effective in the best possible way.
- This method restricts the accumulation of sediments to a defined region which makes it easier to manage the sedimentation issue.
3. Sediment removal
- In this, the removal of sediments is done using various methods, and it removes sediment from beneath the river.
- It is one of the most frequently used methods for managing sedimentation issue.
- Few methods are dredging, dry excavation, sediment syphoning etc.
- Though this strategy is limited due to reasons like high cost and unavailability of sites for the dumping of the large volume of extracted sediments.
- The effectiveness of the existing institutions is a matter of concern as a potent institution would have a better chance of resolving the issues of the river.
- Maintaining a fruitful relationship with the transboundary countries also becomes a concern as it is, at times, impacted by the ongoing political ties between the countries.
- Aspects of policy issues or gaps should be addressed to enable better handling of the river.
- Establishment of a dedicated and independent body that is entirely devoted to taking care of the river.
- Respecting the viewpoints of every stakeholder involved and bringing a collaborative approach in resolving the issues concerning the river.
- Forming an international regulatory body that takes care of the transboundary issues and ensures that the benefits reaped from the river are equally enjoyed by every country involved.
- Precise sediment classification can facilitate effective desiltation and can also help in preventing further siltation by providing a deeper understanding of the siltation process.
“It's critical to consider downstream concerns in order to develop a better system for human well-being and environmental sustainability at the river basin scale.”