Role of Farakka Barrage on the Disastrous 1998 Flood in Malda (West Bengal)

Abstract

The Farakka barrage (Figure 3.1 and Box 3.1) was constructed in 1971 across the mighty river Ganga (Ganges) to divert part of the main river flow from Ganga to its tributary, the Hooghly (Figure 3.1). With gradual silting of the Hooghly off-take near Jangipur in the Murshidabad District of West Bengal, upland discharge to the Hooghly was being reduced drastically (Mookerjea, 1974). The problems of the Hooghly are high salinity, heavy siltation, poor navigability and the increasing frequency and intensity of tidal bores (Abbas A.T., 1984). Depth of the Hooghly was reduced due to the deposition of sediments carried by the high tides from the Bay of Bengal. Accelerated sedimentation, usually observed in the zone of saline and freshwater interface, has very high spatial and temporal variation. Annual dredging costs increased to Rs. 315 million (unadjusted) in 2001 from Rs. 75 million in 1973 to permit the navigability of the river where the port of Kolkata is situated (The Hindu, 2001). Model studies at Central Water and Power Research Station (CW and PRS), Pune, as well as at River Research Institute, West Bengal, were carried out to determine the amount of Ganga flow that must be diverted to the Hooghly for flushing out the sediments and restoring its navigability. From these model studies as well as some analytical studies conducted by the hydraulic experts Dr. Hansen from Germany and Engineer Joglekar from India, it was finally decided to divert 1,134 m3/sec (40,000 ft3/sec) of flow. Accordingly, the Farakka Barrage and the feeder canal linking the Ganga with the Hooghly River were constructed at an approximate cost of Rs. 2,000 million (1971 price).