Study of Sediment Transportation in the Gulf of Kachchh, using 3D Hydro-dynamic Model Simulation and Satellite Data

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dc.contributor.advisor Sugimori, Y. Kunte, P.D. 2006-08-14T09:06:29Z 2006-08-14T09:06:29Z 2003
dc.identifier.citation Ph.D. thesis, Chiba University, Japan - National Institute of Oceanography, Goa, India
dc.description.abstract A 3D hydrodynamic model ‘COSMOS’ is applied to the Gulf of Kachchh to predict tidal variation, ocean currents, residual tidal current, sea surface temperature distribution etc. The model is based on the hydrostatic and Boussinesq approximations and uses a vertical double sigma co-ordinate with a step-like grid. In addition to the momentum and continuity equations, the model solves two-transport equations for salinity and temperature and an equation of state to include the baroclinic effects. The other objectives are to quantitatively assess suspended sediments by digitally analyzing SeaWiFS data using SeaDAS software and to monitor suspended sediment movement by image processing of ocean color monitor data and finally establish relations between residual tidal currents and sediment transport. The Gulf of the Kachcha (GoK) lies approximately between latitudes 220 to 230 N and between longitudes 69000’E to 70045’ E. The GoK presents a complex macro-tidal region. The model is set up for the GoK, and is validated using remotely sensed data. Sea surface temperature, Salinity, river input, meteorological parameters and five components of tide are utilized in COSMOS model. Five boundary conditions, such as land-ocean boundary, air-sea boundary, sea bottom friction boundary, discharge from river boundary and Gulf-open ocean (open) boundary are defined and used. Programs constituting the COSMOS model were executed along with initial input cards to simulate the model using an Alpher mini-computer system at the CEReS, for November and December months of 1999. While modeling, the water column is divided into five layers and at each layer the distribution of current velocity and direction, pressure water temperature, salinity and turbulent energy were computed. Comparing the simulated results with the measured data available for those locations has validated the model. The model results showed that the dominant current system is controlled by tidal variation. The tidal and residual tidal currents simulated by the model are similar to the results obtained by previous researchers. Surface current distribution slightly changes if wind stress is applied to the model. The subsurface layers and bottom layer display almost similar current distribution patterns. However, current speed reduces from the surface towards the bottom. Residual current velocity distribution displays an anti-cyclonic eddy. Several divergence and convergence areas were located in the center of the GoK. The current velocity decreased from 50 to 20 cm/s and the eddy pattern vanishes under uniform depth, which concludes that bottom topography plays an important role in determining the distribution of residual current velocity. The model results of sea surface temperature showed good agreement with temperature structure and pattern obtained form NOAA/AVHRR Data. From sediment plume pattern studies using Sea WiFS and OCM images, it was concluded that the sediments are transported to the Gulf from the north as well as the south and are seasonally dependent. The residual current velocity distribution map for Dec-99 matches well with the map showing gross geomorphic subdivisions of the Gulf of Kachchh. Whereas, sediment distribution boundaries roughly match with those boundaries defined by current velocity distribution. A properly validated hydrodynamic model and sediment transport study of the Gulf would be of interest for coastal defense, management and economic purpose.
dc.description.sponsorship Japan Society for Promotion of Science, (JSPS), Japan
dc.format.extent 4881574 bytes
dc.format.mimetype application/pdf
dc.language.iso en
dc.subject Hydrodynamic modeling
dc.subject Sediment transportation
dc.subject Gulf of Kachchh
dc.subject Remote Sensing
dc.title Study of Sediment Transportation in the Gulf of Kachchh, using 3D Hydro-dynamic Model Simulation and Satellite Data
dc.type Thesis

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