Indian Journal of Geo Marine Sciences Vol. 47 (07), July 2018, pp. 1376-1382 The evolution of Balari Bar in the Hugli Estuary, West Bengal, India, and its impact on navigation Aparajita Sen* & Sunando Bandyopadhyay ** Department of Geography, University of Calcutta, Kolkata 700019, India [E.Mail: *aparajita72@gmail.com **sunando@live.com] Received 13 May 2016; revised 10 October 2016 Systematic study of charts, maps and satellite images pertaining to 1967-68, 1975, 1992, 1997, 2000, 2003, 2006, 2009 and 2012, indicate that the Balari Bar steadily increased, choking up the northern portion of the Haldia Channel, on the west of the Hugli Estuary. Its rapid growth, from 0.29 km 2 in 1997 to 3.83 km 2 in 2012, started to threaten the Haldia Dock Complex (HDC). Eight superimposed profiles across the 15 km Balari Reach of the estuary show gradual deterioration of the western Haldia Channel and the improvement of the eastern Rangafalla Channel resulting in the concentration of the tidal flows in the latter. The decrease in the overall capacity of the reach has been 8.13% from 2000 to 2012. The result of this is reflected on the performance of the HDC as some of its share of cargo is diverted to the other sea ports in the vicinity. [Keywords: Estuary, Hugli, Balari, Haldia] Introduction The Bhagirathi–Hugli is the westernmost distributary of the Ganga delta (Fig.1). In the historical times there has been a consistent eastward shift of the off-take points of the Bhagirathi–Hugli. 1 The discharge from the Ganga has also dwindled over the years. Between 1914 and 1970, the maximum discharge through the Bhagirathi at Jangipur, close to its off-take, reduced gradually from 3,022 to 1,306 cumecs with extremely low dry-season discharge. 2 This meagre flow resulted in rapid siltation in the river bed and the crucial lower reach of the river from Cossipore to Hugli Point got choked up by several bars which restricted the movement of the ships to and from the Kolkata Dock System (KDS). In 1977, the total volume of bank erosion along the Bhagirathi was 30.36×10 6 m 3 . 2 It was estimated that about 220 hectares of land is lost every year along the banks of the Bhagirathi–Hugli. 3 Thus a large volume of sediment started to get added to the Bhagirathi–Hugli channel, which is transported to the estuarine reach south of Hugli Point. The Hugli is a flood-dominated macrotidal estuary with the tidal range varying from 4.3 at the mouth to 4.9 m at Haldia and 5 m at Diamond Harbour, situated 43 km and 70 km upstream. At its mouth, the maximum flood and ebb discharges of the estuary is estimated at 2.6×10 5 and 1.1×10 5 cumecs respectively. 4 The duration of flood tide is about 3 hours in a 12.4 hour tidal cycle, setting up flood velocities in the range of 2–3 m s –1 , compared to ebb velocities of <1 m s –1 . 5 This results in a net landward movement of sediments due to the time-velocity asymmetry in tidal propagation, making it a sediment sink. 6 It is estimated that in the upper section of the Balari Reach, 51 km from the mouth of the estuary, maximum flood and ebb discharges amount to 6.7×10 4 and 3.7×10 4 cumecs respectively, 7 resulting in 2.5-times higher bedload transport during the floods compared to the ebbs. 8 These features of the Hugli are common to many macrotidal estuaries of the world. 9 During the 20th Century, the Hugli gradually became incapable in accommodating the large ocean liners. The percentage of the total volume of cargo handled by the KDS fell from 49.5% of the India’s total in 1928-29 to only 10.7% in 1970-71. 10,11 Although the Hugli estuary is primarily a sediment sink, active reworking of the deposited material and consequent shifting shoals and bars occurred all through its recorded history. 12,13,14,15 The Jiggerkhali Flat and the Balari Bar was ignored while the plans were made for the construction of the Haldia Dock Complex (HDC) on the western bank of the Hugli as it was thought that these could be easily tackled by some localised dredging. 16 The evolutionary history of the estuarine islands of the Hugli were studied by Chakrabarti, 17 Kumar et al., 18 Prithviraj et al., 19 Bandyopadhyay, 14 Bandyopadhyay et al., 20 and