Representation to GOWB on Alternatives to Farakka Barrage
Hon’ble Shri Rajib Banerjee, Minister
Department of Irrigation and Waterways
Government of West Bengal
We wish to bring to your kind notice that the Farakka Barrage Project has imposed huge hardships to the people of the State.
Indeed, some benefits have been obtained. These include reduction of salinity, enabling of shipping, and improved drinking water supply to Kolkata. However, the negative impacts of erosion, loss of fisheries and increased cost of dredging are much greater.
Your Hon’ble self may therefore consider revisiting the issue of revival of Bhagirathi-Hooghly system de novo. The possibility of diverting water of the Ganga to the Bhagirathi by making a weir may be considered; and the possibility of developing a Deep Sea Port may be considered.
We are attaching a short note on these matters for your kind consideration.
Debasis Bandyopadhyay, Dumkal College, Basantapur, Murshidabad.
Mitul Ganguly, Kolkata
Dhrubajyoti Ghosh, Kolkata
Niranjan Haldar, Kolkata
Bharat Jhunjhunwala, Formerly Assistant Professor, IIM, Bengaluru
L V Kumar, Formerly CMD, WAPCOS, New Delhi.
Santosh Kumar, Patna
Dinesh Kumar Mishra, Jamshedpur
Manoj Mishra, Jamuna Jiye, New Delhi
Bijay Sarkar, Kakdwip. Retired school teacher. Narmada Bachao Andolan.
Tarun Sengupta, Lecturer, Malda
V N Sharma, Jamshedpur
Debadityo Sinha, Coordinator, Vindhya Bachao Abhiyan, Mirzapur
Shri Dhiman Mukherjee, Secretary, IWD, GOWB
Farakka Barrage was made in the 70s with the objective of increasing flow of water to the Hooghly to reduce the requirement of dredging in the Bhagirathi-Hooghly and to enable movement of large ships to the Kolkata Port. These objectives have been partially attained. Dredging in the Jangipur-Diamond Harbour stretch has reduced and movement of ships up to Haldia has become easy even though the expected draft has not been attained.
However, various negative impacts have since been noticed.
1 Problems due to creation of a pond at FBP to divert water with less sediments to the Hooghly via the Feeder Canal:
a. Loss of fisheries upstream of FBP. Fish migration is obstructed. The fish lock at Farakka has been dysfunctional for many decades.
b. Loss of aquatic and floral biodiversity both upstream FBP and in the Hooghly Estuary. The flow regime upstream has been altered to a distance of about 100 km. This change is impacting biodiversity upstream. The change in sediment regime and deprivation of flood flows have affected biodiversity in the Hooghly Estuary and the Sunderbans.
c. Creation of pond upstream is leading to lateral expansion of the river bed and erosion. Flushing of the pond leads to release of water at high velocity and to erosion downstream.
d. Dangers of Ganga outflanking the FBP. The pond has led to aggradation of riverbed, horizontal spread and to the possibility of Ganga outflanking the Farakka Barrage. The Ganga upstream is moving eastward and may join the Pagla in a flood event.
2 Problems due to Feeder Canal: Increased flood congestion and water-logging west of the Feeder Canal has taken place due to obstruction of natural drainage channels.
3 Problems due to reduced supply of sediments and flood flows:
a. At present the water is diverted from the Farakka Barrage to the Feeder Canal. The sediments are mostly flushed to the Padma. This creates a sediment imbalance on both sides of the FBP. On the Hooghly side, less sediment supply is leading to erosion in the Hooghly Estuary. On the Padma side, more supply of sediments is leading to riverbed aggradation and increased flooding.
b. Reduced supply of sediments has led to the sea eroding the islands on the coast and depositing the sediments upstream. Tidal sediments have blocked much of the Haldia Channel.
c. Cost has to be incurred in making of the underwater guide wall at Haldia to counteract the increased deposition of tidal sediments. This problem has arisen because reduction in flood flows is not flushing the tidal sediments to the sea.
d. Discontinuous flow at 10-day cycle from FBP is being made to ensure a flow of 40k cusecs to Hooghly and Padma in consecutive 10-day periods with excess being supplied to the other side. This discontinuous flow is leading to ingress of sea during the lean 10 days and to increased salinity of ground water in the Hooghly Estuary.
The driving consideration at the time of planning of the FBP was the increasing cost of dredging of the Bhagirathi. The costs of these negative impacts were was not known and not taken into account. Now, these negative impacts have become known. Therefore, there is a need to reexamine whether dredging of the Bhagirathi would be economically beneficial in these changed circumstances.
Proposal 1: Diversion Structure
A low-height weir with undersluices can be made across the Ganga within Indian territory near the International Border. There will be no pondage. The weir will work as a “controlled” spur if undersluices on the northern side are raised and on the southern side are lowered. The undersluices can be operated to divert water in desired quantity. The weir will push desired quantity of water in the Hooghly. The important difference will be that sediments will be distributed along with the water; and flood flows will also move into the Hooghly. This will provide sediment supply to the Hooghly Estuary and also flood flows to flush the sediments, including tidal sediments, to the sea. Dredging of the Bhagirathi may, however, have to be done to draw waters from the weir.
Gates of the FBP may be removed and the existing structure may serve as a bridge.
The embankments made for the protection of Bhuti Island on the right bank has diverted waters to the left bank at Farakka. A similar spur on the left bank could, therefore, divert waters to the Bhagirathi. The proposed weir will operate like such a spur.
Such a diversion structure will eliminate the various problems enumerated above that are occurring due to
(1) The pond at FBP will be removed and problems of erosion associated with it will be removed.
(2) The Feeder Canal can be decommissioned and replaced with a smaller supply canal to meet the requirements of Thermal Plants and localities that have come up along its course.
(3) Increased supply of sediments to the Hooghly Estuary will counter coastal erosion.
(4) Restoration of flood flows will flush the sediments into the sea.
The main costs to be incurred in this proposal will be
1 Increased cost of dredging the Bhagirathi. The dredging requirement will be mainly at the offtake of the proposed weir. The flow will follow its natural course once water is diverted into the Bhagirathi.
2 Increased cost of supplying water to the Farakka Super Power Thermal Station and other users that have sprung up along the Feeder Canal. Pumping of water may be required to meet these uses.
3 Reduced groundwater recharge due to removal of the large reservoir.
The benefits from supply of water to Kolkata and provision of bridge between south- and north Bengal would continue unimpaired.
GOI is considering the development of a deep sea port at Sagar Island. We submit this will face all the problems presently faced by Haldia port because the problems arising out of (1) Creation of a pond at FBP; (2) Feeder Canal: (3) Reduced supply of sediments to the Hooghly Estuary; and (4) Elimination of flood flows in the Bhagirathi-Hooghly will not be abated.
Counterargument: FBP says that dredging the pond is not a solution as the channel gets filled up in subsequent floods.
Reply: The above comment was made by FBP in respect of dredging within the pond of FBP. The dynamics of dredging would be entirely different in a free flowing river. Much sediments will be carried by the Bhagirathi and the Padma without requiring dredging. Some filling up will certainly take place but the cost of dredging would be less because the free-flowing river would carry some of the dredged materials to the sea, especially in the flood flows during the monsoons.
Model studies are required to be done to assess how much of the dredged sediments in the Upper Bhagirathi will be carried by the river to the Sea. Most sediments are obtained during the monsoons when flood flows will also be available hence the increased requirement of dredging would be small.
Counterargument: The option of dredging was considered at the time of planning of the FBP and found unviable.
Reply: Ultimately the question is of economic viability. At the time of planning the FBP, the various negative impacts enumerated above were not known. The cost of dredging, therefore, may have been assessed to be more than the benefits. The same cost may now be less as various costs have become known.
Counterargument: Constructing a diversion structure or spur is not going to work in the long run because without ponding at the barrage, water level cannot be raised so that discharge can enter into the Bhagirathi-Hooghly year round. No amount of dredging would be able to solve this problem permanently because (i) Maintenance dredging has to be continued every year and (ii) Bhagirathi will have to be dredged up to a great distance away from the mouth to maintain their hydraulic gradient vis-à-vis the Ganga-Padma.
Reply: The diversion structure will lead to deposition of sediments on the upstream and raise the riverbed level of the Ganga. The diversion structure may have to be designed for such aggradation of the riverbed. That will enable water to be diverted into the Bhagirathi.
Maintenance dredging will indeed have to be carried every year. This will entail heavy expenditures. Our submission is that a techno-economic assessment of various options in dredging has to be made. It must not be assumed that the cost of dredging would be more than the various costs enumerated at the head of this note.
Counterargument: The course of the Ganga downstream of Suti is a rapidly degrading channel separated by a sandbank (char) from the main flow of the mighty river. These sandbanks are inherently unstable, extremely liable to close completely and can render little support to any major diversion structure.
Reply: This is an engineering problem. Engineers must be asked to assess the cost of a structure that will hold in these conditions.
Proposal 2: Deep Sea Port
Another alternative is to abandon the efforts to make the Bhagirathi-Hooghly-Hooghly Estuary system into a waterway. A Deep Sea Port is already functioning in the Bay of Bengal. This may be developed and the cargo can be carried on smaller boats requiring less draft that are navigable in the natural flows.
GOWB may commission a techno-economic study on:
1 The feasibility of making a weir as suggested above;
2 Developing a Deep Sea Port instead of insisting that the Hooghly be made navigable for large ships.