Dredging the Hugli Estuary
CEDA Dredging Days 2017 - Sustainable Dredging - Continued Benefits
Kirkpatrick J., Barber D., Chaudhuri B.
Abstract: Established maintenance dredging practices in ports and harbours are not always optimal, and improvements can often be made to enhance both the economic and the environmental management of a port authority. This paper describes a recent example where both economic and environmental improvements were achieved.
Kolkata Port has been in operation for over two centuries, with the Haldia Dock Complex being operational for almost 40 years. During this period, maintenance of the approach to the ports has been an ongoing concern and this region has the largest maintenance dredging burden of all Indian ports.
HR Wallingford was initially commissioned by WAPCOS Ltd (A Government of India Undertaking) in August 2012 to provide an ‘Expert Third Party Opinion on River Regulatory Measures’ on the Hugli Estuary. A review was undertaken which identified short-term improvement measures. The drivers for the subsequent project (and the focus of this paper) were to improve the efficiency of the maintenance dredging works, reduce dredging costs, and provide increased channel depth. The novel short-term solution identified successfully achieved this and allowed a drastic increase in dredging efficiency. Moreover, the change in methodology allowed significant environmental improvements to be made: carbon dioxide emissions were significantly reduced due to reduced sailing distances, and sediment was better kept within the sediment transport system with a major reduction in offshore placement. Turbidity was increased as a consequence of the short-term solution used, but this was in an environment already characterised by high natural turbidities and subject to anthropogenic changes.
This paper describes the substantial challenges addressed by the project, the novel solution that was identified, trialled and implemented by the project team (including observations from site visits), and the search for a winwin solution.
Key words: Hugli, river, maintenance, side-cast, agitation.