Nearshore Hydrodynamics Near an Open Coast Harbour at Gopalpur, Central East Coast of India

Abstract

Nearshore hydrodynamics of a particular region is largely controlled by the tide, current, local bathymetry and significantly modulated by the harbour and associated structures along the coastal front. Along the east coast of India, Gopalpur (19° 18′ 13″ N; 84° 57′ 52″ E), a minor seasonal harbour is under phases of renovation to a major all-weather port have ensued alarming changes along the coast. In view of the ongoing changes, water level and flow patterns along a 28 km stretch of the coastline for three different seasons viz., fair weather (December 2008), southwest (May 2009) and northeast (November 2009) monsoons were investigated. A numerical model was constructed to understand the spatiotemporal hydrodynamic regime for the region and future application from integrated coastal zone management perspectives. The study reveals that the tide is predominantly semidiurnal; M2 is the major tidal constituent contributing nearly half of the total tidal amplitude (0.48–0.55 m) followed by S2 constituent (0.20–0.25 m). The seasonal mean current speed was in the order of fair weather (20 cm/s) > southwest monsoon (19 cm/s) > northeast monsoon (15 cm/s). A two-dimensional hydrodynamic model was set-up, calibrated and the model performance was evaluated through various skill analyses. The correlation (r) for surface elevations were 0.96, 0.98 and 0.98 whereas 0.8, 0.96 and 0.75 in current during fair weather, SW and NE monsoons, respectively. The relative mean absolute error (RMAE) and index of agreement (IoAD) refer that the model works out to be ‘excellent’ for surface elevations and ‘very good’ for currents.