GUWAHATI: Assam has almost become synonymous with floods. Each year the state witnesses devastation caused by the overflowing of the Brahmaputra River - the mighty river which flows through the entire state – and its numerous tributaries.
The Brahmaputra river system is a mega river system which dissects the entire Brahmaputra river valley. The water of the main stem of Brahmaputra is also supplemented by around 57 north bank tributaries and 33 south bank tributaries.
This year alone the floods have claimed 91 lives so far in Assam and affected more than 53 lakh people.
As per a Central Water Commission report on the annual Assam floods between the years 1953 and 2016, close to 26 lakh people are affected on an average every year due to floods in Assam. The total annual average damages to crops, houses and public utilities stands at Rs 123.39 crores. Additionally, the floods kill 47 people on an average each year.
The flood of 2004 was a particularly devastating one in recent times as it recorded 1.26 crore people affected - which is the maximum since 1953. The year also saw the highest death toll which stood at 497.
Further, 2012 saw the highest damage worth Rs 3,200 crores due to floods.
Here’s a look at the history of the floods and the reasons why they occur every year causing destruction to humans, wildlife and property.
History & major reasons behind floods
Floods are not a new phenomenon for Assam and its people as the state has been experiencing flooding every year for centuries. Experts claim that even the chronicles of Ahom monarchs repeatedly mention floods.
Since ages, the people of the Brahmaputra valley have learnt to live with floods.
For instance, people of the Mising community are intimately connected with the river and they build their houses at a raised level to prevent flood water from entering their houses. Most of them also own boats making them self-sufficient when the deluge occurs.
The Brahmaputra River originates in Tibet traversing the Tibetan Plateau after which it enters Arunachal Pradesh and then flows across Assam. On the way, the river also merges with its tributaries in Bangladesh and finally flows into the Bay of Bengal.
As the river flows from a higher altitude to the plains in Assam at a high speed on the slope, it carries with it a large load of sediments and debris. It also causes landslides and the silt is deposited in the river bed thereby continuously raising its height.
During the summer season, melting of the Himalayan glaciers and monsoon rains combine together resulting in the annual floods.
“Both of these factors contribute a huge amount of water into the main stem as well as the tributaries. All the water flow comes and gets discharged in the Brahmaputra River. This is why flooding occurs continuously,” said Arup Kumar Dutta, author of “The Brahmaputra.”
To add to this, meteorologically, Assam is part of a zone which receives excess monsoon rains and is also prone to earthquakes which only makes matters worse.
Dutta mentioned that another important factor which majorly affected the flood scenario in Assam was the destruction caused by a devastating earthquake in 1950 which led to change in the topography of the region.
“The earthquake of 1950 was a devastating one which lifted up the bed of the Brahmaputra River by almost 3-5 metres therefore reducing the river channel’s capacity to hold water,” he explained.
This is why the impact of flooding has worsened in the state after 1950.
Experts point out that some other factors which contribute to floods include the man-induced destruction of wetlands. These wetlands used to absorb the excess water flowing from the river but now with the large-scale destruction of wetlands, water holding capacity of banks has reduced aggravating the problem.
Rising population also contributes to floods. Previously because of lesser population, people used to stay away from the banks. So, excess water in the river also used to pass through a given area without causing damage to property as well as human lives.
But now due to population pressure, a large number of people have started utilising the areas near the river for living purposes. This has ultimately led to reduction of flow path of river basin which has aggravated the problem and has accentuated the flood damages, claim experts.
What is the role of climate change?
Guwahati based civil engineer, JN Khataniar, is of the opinion that in the coming years, climate change could play a major role in floods.
“Rainfall is dependent on global warming and climate change. So, we sometimes experience heavy rains and in other years, moderate rains and temperature,” he said adding that climate change and increased population coupled with deforestation and emission of green house gases could make matters worse for Assam floods.
Khataniar has also recently developed a model of a floating residential house for flood prone areas. He is now trying to get his concept of the floating house included in the Prime Minister Awas Yojana (PMAY).
“Whenever floods will come, the house will vertically move upwards and when the water recedes, it will come back to its original position without displacement. I am also writing to the Prime Minister to include this model in the Prime Minister Awas Yojana for flood prone areas,” he told G Plus.
Dredging the Brahmaputra River: Viability questioned
The Assam government had planned to conduct dredging along a 891 kilometre stretch of the Brahmaputra River a few years ago. This project was also sanctioned by the central government and the estimated project cost for this was Rs 40,000 crores.
The process of dredging involves removing debris and silt from the bottom of the river using a dredging machine. The proposed project also included construction of an expressway on both sides of the Brahmaputra River.
Regarding this, Chief Minister Sarbananda Sonowal also held a meeting with officials from Dredging Corporation of India.
A press release stated, “In order to give succour to the people ravaged by perennial floods and erosion, state government with the help of Dredging Corporation of India, will start dredging of river Brahmaputra."
It was also decided that first a survey would be conducted based on which an action plan would be prepared for dredging on an annual basis. But the plan is yet to come to life and still remains on paper.
On the other hand, environmental experts claim that dredging is not a viable solution to the floods and have questioned its sustainability.
“As the river flows downstream from the hills, it is at a high momentum and carries with it a large amount of silt which gets deposited in the river bed when the river enters the plain. This is a continuous process. So if the government plans dredging, they will have to do it continually,” said Dutta.
Proposed solutions undertaken
Experts claim that given the complexity of the matter, a permanent solution to the flood problem of Assam is almost impossible. However, the government, in collaboration with the Brahmaputra Board - a body established under the central government to mitigate floods in the Brahmaputra, has undertaken some measures with a view to mitigate damages caused by floods.
VD Roy, secretary of the Brahmaputra Board told G Plus that they have been working on a number of flood prevention measures throughout the year to control the wrath of floods.
He said that the Board is carrying out continuous surveys of the Brahmaputra River from time to time and are also building different kinds of structures to control flood water. These include:
Embankments: These are constructed to check the spillage of flood water and to control erosion and are a temporary solution for floods. However, poorly maintained embankments are proving to be a problem in itself. Now, the embankments are becoming old and there is a lot of erosion which is aggravating the problem rather than solving it, says Dutta.
Geo bags: Geo bags or geotextile bags are filled with sand and placed along the banks of the river to prevent flood water from spilling over and are also used to check erosion, said Roy. This has been majorly implemented in Majuli, he added.
RCC porcupine screens: These structures are installed to slow down the speed of the river flow, induce siltation from the bank and decelerate the erosion from the bank. Water flows through this structure and thus reduces the flow the river.
Drainage development scheme: Officials informed that apart from anti-erosion work, the Brahmaputra Board is also working on drainage development scheme. “During floods, water logging in low lying areas proves to be a problem. Drainage development will help to provide suitable channel for water from the low lying area to the river system,” informed Roy.
Construction of raised platforms: Apart from the above-mentioned measures, raised platforms have also been constructed in some areas for victims to take shelter.
What can be the way forward?
Experts say that a combination of various measures and a holistic approach is the only way to deal with floods.
The Brahmaputra Board is working with Assam State Disaster Management Authority for flood forecasting. Authorities claim that flood forecasting has helped in reducing the death toll from floods over the years.
Roy informed that another solution to mitigate the destruction caused by floods is flood plane zoning.
It consists of creating some zones on the banks of the river based on floods of past years. For this, areas are identified as flood prone and construction of establishments is allowed according to how prone the area is to flooding.
For example, in areas immediately next to the river bank, no permanent structure is allowed.
Further, in areas which can be easily evacuated and are only sometimes flooded, here those establishments can be constructed which can be easily evacuated in case of flood like playground, schools and colleges. Additionally, in the next zone which is rarely flooded, important installations like hospitals, grain godowns etc can be given the permission to be constructed.
However, this requires proper identification and regulation which is possible only after the government enacts a bill.
“Central water commission has been emphasising on it for a long time now. But till now only a few states including Manipur, Uttarakhand and Rajasthan have enacted the bill,” said Roy.
Experts say that governments shy away from implementing it since regulation is a big challenge in flood plane zoning.