Bihar Floods| Floods| Ganga River| Chief Minister of Bihar| Nitish Kumar| Farakka Barrage| Sediment|
Bihar and Bengal are facing huge floods brought by the Ganga River. A number of people including Chief Minister of Bihar Nitish Kumar hold that the problem is because of the Farakka Barrage. They say that the flow of the Ganga is obstructed by the Farakka Barrage due to which the sediments start depositing behind the Farakka Barrage. The depth of the Ganga upstream of Farakka is becoming less. This makes it difficult for the Ganga to carry the water downstream and the intensity of the floods increases by the year.
Sedimentation| Government of Bihar| Rajiv Sinha| IIT Kanpur| Stretch of Ganga| Buxar| Patna|Gandhighat|
In order to assess the nature of sedimentation in the Ganga, the Government of Bihar had given an assignment to Dr Rajiv Sinha of IIT Kanpur to study the same. Sedimentation means that the amount of sand and other material such as clay is deposited in the bed of the River. Dr Sinha found that the stretch of Ganga from Buxar to Patna is choked and is full with sediments. It does not have any capacity to retain any more sediments. This area of the Ganga is like a bucket full of sand. If we pour more sand laden water into the bucket, then the water along with the sand will pass through because there is no more space left in the bucket to hold more sand. In a similar manner the stretch from Buxar to Patna (Gandhighat) is full of sediments and whatever sediments are now brought by the Ghagra or the Ganga are carried downstream. See Report Here:
Dr Sinha also says that the Farakka Barrage has changed the dynamics of the flow of the River. He points out that in Bhagalpur a huge amount of sedimentation is taking place. He says that sedimentation is taking but is not visible upstream Farakka because the Barrage has created a huge pond about 80 kilometres long. The sediment that is coming from Patna is getting settled inside this pond. So on the surface it is not visible but the underwater level of sediments is rising.
Although Dr Sinha does not say so, in our opinion, this is influenced by the Farakka Barrage which is leading to a reduction in the velocity of the Ganga and making it difficult for the Ganga to carry the sediments to the sea.
Ganga| Sediments| Remove Farakka| Flood Water| Flushing the Sediments| Flood Water Velocity| Power of Flood Water|
It is clear that the Ganga is bringing sediments; they cannot be held upstream Patna; they are getting deposited between Patna and Farakka; this deposition is leading to a reduction in the depth of the Ganga; making the cross section of the river less leading to reduced capacity of the Ganga to carry waters which is leading to floods.
Sediments Deposit| Increase in Floods| Depth of River Bed| Sea| Cleaning up River| Sediment Depositing Stretch|
Now, what is the solution? A number of observers say that if we allow the floods to take place and remove the Farakka, it will increase the velocity of water and the flood will flush the sediments into the sea. It will clean up the bed of the Ganga and in the subsequent years the flood will be less.
Dr Sinha does not agree with this perspective. Dr Sinha says that the flood is bringing the sediments with it. Therefore, during the flood more sediment will get deposited in that area and lead to the increase in the flood in subsequent years. Or, the floods cause more deposition of sediments, lead to less depth of the water, and leads to more floods.
We think that the views of the observers are more likely to be correct. The reason is that if floods were only depositing the sediments, then in thousands of years when the floods have been taking place the entire area should have been full of sediments. The vary fact is that the river has made a channel for itself and the sediments have not completely filled up the channel is itself establishes that the floods also have been flushing the sediments during the last thousands of years.
We submit that the floods have two functions. One, the smaller floods bring more sediment and deposit them. Two, the bigger floods flush the sediments to the sea.
Allowing the Floods| Capacity of River| Farakka| Monsoons| Monsoon Floods| Obstruction of River Flow| Situation of Floods
Our submission is that if we remove the Farakka and also allow the floods to take place, we will be adding to the capacity of the river to flush the sediments during bigger floods. However, if we obstruct the flow of Ganga at Farakka, then the same floods will have a totally different dynamics. In that case the Ganga will be bringing more sediments during the floods but due to the obstruction at Farakka, the floods will not have the velocity to flush the sediments to the sea. In this situation, floods can lead to more deposition of sediments and more floods—as Dr Rajiv Sinha is saying.
We submit that we need to do two things. One, we need to allow the floods to take place so that the sediments can be flushed. We should not trap the floods in the Tehri Dam or reduce the floods throughout the monsoons by continued abstraction for irrigation. Second, we need to redesign the Farakka Barrage so that the velocity of the river is not obstructed. Unless we do both these things, the problem of sedimentation between Patna and Farakka will not get solved and the floods will continue to get worse.
