Hydrodynamic Modelling for Development of a Port in an Estuary

Abstract

Sharavathi River originates and flows entirely within the state of Karnataka in India. It is one of the few westward flowing rivers of India with huge discharge during monsoon, and the major part of the river basin lies in the Western Ghats. The total length of the Sharavathi River is around 128 km, and it joins the Arabian Sea at Honnavar in Uttara Kannada district of Karnataka. The present study deals with the development of port for providing berthing facilities for coal and iron ore-carrying vessels of 10,000 DWT capacity in the basin of the Sharavathi River estuary. The channel as well as harbour area is proposed to be dredged up to −10.0 m depth. A computer-based numerical model was developed for the port in the Sharavathi Estuary to examine the hydrodynamic characteristics of the region. The model highly resolved the region of interest and predicted sea level, currents in response to the effects of tides and slow sea level changes. Such a model could be used to predict the movements of sediments throughout the vicinity of the proposed harbour. Tidal hydrodynamic simulations reveal that the flow field is conducive without significant circulation with the suggested modified layout. The annual deposition of sediment is expected, in the approach channel. The capital dredging for proposed port development is estimated to be about 4.0 M Cum, and the total maintenance dredging is estimated to be about 1.0 M Cum. Results from the model show that the currents in the estuary are predominantly due to the effects of the tide; the tidal range is around 1.58 m. These tides can generate currents, with current speeds reaching up to 1.3 m/s in the vicinity of Badagani Estuary in the North and up to 0.8 m/s in the vicinity of Sharavathi Estuary in the south. The simulations generated by the model and associated analyses provide a first-order picture of the flow and distribution characteristics of the port environment which may aid in management decision processes and provide an enhanced understanding of the oceanography of the region.