Great zigzag shift towards original path

Scientific studies have proved that the Ganga shifted in a zigzag manner between Ara and Patna during the 25-year period between 1975 and 2000 looking the river closer to the city.

By Piyush Kumar Tripathi
  • Published 10.04.15
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SAVE GANGA 

An aerial view of the dried-up bank of the Ganga behind Golghar on Thursday. Picture by Ashok Sinha

Scientific studies have proved that the Ganga shifted in a zigzag manner between Ara and Patna during the 25-year period between 1975 and 2000 looking the river closer to the city.

The only good news from experts working on the Ganga is a recent trend being observed in the shift of the river towards its original course near Patna.

Starting from Ara in the west, the river shifted southward from its original course till Danapur during the last quarter in the 21st century. While moving further east from Danapur, the river shifted towards its northern bank from Digha to Hajipur during the same period.

As a result, the river looks closer to the city near Danapur and away from the city near Kurji.

Without taking such reports and scientific observations on movement of the Ganga in consideration, the state government has decided to make a man-made shift in the river course by digging a new channel along the city. The work on digging up the 7.1km long and 30m wide channel is expected to start from April 18.

A recent study by National Institute of Hydrology (NIH), Patna, titled, Evaluation of shifting characteristics of river Ganga between Ara and Patna from 1975 to 2000, stated that the river had shifted northward as well as southward from its original course along this stretch.

According to the report, the shift in the main course of the river is in the range of 1.45km to 2.76km.

The maximum shifting of 2.76km has occurred at Neknamtola near Ara while the river widening of 3.8km is maximum at Daudpur near Danapur. The rate of shifting of 0.11km per year is highest at Neknamtola while the rate of river widening at Daudpur is 0.15km per year. (See graphic)

"For the purpose of studying the shifting characteristics of river Ganga between Ara and Patna over a length of 66km, satellite remote sensing data was collected for 1974-76, 1989, 1996, 1998 and 2000. The report suggests that the shift has happened southward (towards the city) between Ara and Danapur and northward (away from the city) between Digha and Hajipur. As a result of the shifting and consequent erosion of the riverbank, many villages on either side, locally known as diara, have either vanished or have come up anew," said a senior official at NIH-Patna wishing anonymity.

The NIH report states that the Ganga flows mainly from west to east from Dighwara to Nayagaon (Saran district) and after that it takes almost a right turn in south direction to flow up to Sonepur, where it again flows eastward up to Hajipur.

The major township on the left bank of the river are Dighwara and Hajipur. On the right bank of the river major townships are Danapur and Patna.

Deliberating on the selection of the stretch between Ara and Patna for the study, the NIH official said: "The middle Ganga basin in Bihar is quite prone to river migration. For this reason, the stretch of the Ganga between Ara and Patna was selected for studying river migration pattern. In this stretch, the river changes its course considerably in magnitude as well as direction depending upon the discharge in the river."

While the NIH study gives an assessment over the patter of the shift in the course of the Ganga only up to 2000, experts have claimed that the river has lately started shifting southwards along Patna, which means, it is coming back to its original course along the city.

"Though I have not made any scientific study as such but as per my personal observation, I am of the opinion that the Ganga has started shifting southward along Patna. This has basically happened due to erosion of the southern bank of the river along the city as a result of rampant bridge and building construction activities," said R.K. Sinha, professor of zoology at Patna University, who has worked extensively on the Ganga and Gangetic Dolphin.