Modeling of tidal circulation and sediment transport near tropical estuary, east coast of India

Abstract

Estuarine hydrodynamics is a key factor for altering the inlet and its adjacent morphodynamics. Sediment transport in estuaries is controlled by the hydrodynamic action of wind, wave, tide, currents and river runoff. Sediment transport rate near a tropical estuary i.e., Rushikulya, east coast of India was assessed based on field surveys carried out during 2008 and 2009, covering both southwest and northeast monsoon wind field. A depth-averaged two-dimensional model was used to simulate and estimate sediment transport through a validated hydrodynamic and wave model output. The total sediment load, transport direction and bed level changes were estimated using Mike 21 Sediment Transport (ST) model. During the northeast monsoon, the sediment transport on the south varied from 2 × 10−6 to 6 × 10−6m3/s/m while at north of the inlet, it was constant with a value of 2 × 10−6m3/s/m and transport direction ranges from 330 to 350° at south and 280 to 320° at north. During southwest monsoon, the sediment load ranged from 2 x 10−6 to 2 x 10−5 m3/s/m and transport directions are mostly confined to 100°. Beach profiles and shoreline position confirm the onshore–offshore​ sediment transport. The work provides baseline information, can be used for management to protect the world-famous Olive Ridley nesting beaches, adjacent to the Rushikulya estuary, east coast of India.