Flood affected area: Image by D.K.Mishra
barrages in Bihar are the main cause of floods evrry year in River Ganga

There is a major problem of floods in Bihar and west Bengal. We have given above a picture of the floods in river Kosi in Bihar. The floods in Bihar have become worse because the capacity of the Ganga to carry the flood waters of the incoming tributaries has been reduced. The amount of water that can be carried by the Ganga depends upon the velocity and cross section of the Ganga. The cross section area of the river is reduced due to the deposition of sediments. The gradient of the river also becomes less and leads to lesser velocity. Due to less cross section and gradient, the Ganga cannot carry the flood waters, which leads to heavy floods.

Bihar CM Nitish Kumar has raised this issue and listed the projects; those were started by its government to protect environment and planting 24 crore new plants. Commitment is given below,

“Our goal is to make sure that at least 15% of the state is green. With our continuous efforts, we have attained 10% greenery in Bihar and if everyone pitched in, we can certainly reach the goal of 15% in few years” link is available regarding this comment here.

People gathered in height area due to flood in Kosi River

The Government says that the sediment will be flushed out by barrages. But flushing leads to the removal of sediments for only a very small distance upstream barrage.

We give a photo of an island formed about 2 kilometres upstream of Farakka because the sediments have not been flushed out.

Island formed due to sediments have not been flushed out: photo by Bharat Jhunjhunwala

It is clear that sediments in long stretches of 100 km will not be flushed out. A Report of the Disaster Management Department, Government of West Bengal explains that one of the causes of flood is backing of water in tributaries at their confluence with the Ganga River. Commitment is given below,

“One of the causes of flood is backing of water in tributaries at their confluence with Main River. The Ganga is not able to drain the waters of Mahananda and other rivers when the Ganga rules high upstream and downstream of the Farakka Barrage”. Link for this reference is available here.

A study is taken by the national institute of hydrology indicates that the rainfall may be concentrated in shorter periods due to climate change. Simultaneously the number of rainy days will be fewer and heavy rain events will be more. The detail study of national institute of hydrology is given here. According to another study of WWF that the rainfall will be concentrated in the month of August only. Report by WWF is attached here. {chapter 4, Page 40, para 1}

This will necessitate that Ganga should have higher capacity to carry the flood waters during these short episodes. Below are the images shows the condition of people in rainy season.

People facing problems in rainy days: photo by D.K.Mishra

The Farakka Barrage is increasing the flood damage because of deposition of sediments. It’s our humble request to Prime Minister Mr. Narendra Modi that alternatives to Farakka Barrage must be developed so that sediments is not deposited and people of Bihar are saved from manmade floods.

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