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Tidal characteristics in the Gulf of Khambhat, northern Arabian Sea – based on observation and global tidal model data

Mitra Aditi, Kumar V. Sanil, Jena Basanta K.

Oceanologia

2020

No. 62 (4PA)

443--459

Tidal characteristics of the Gulf of Khambhat are described based on measured and modelled sea-level data. Data were recorded at three locations inside and two locations outside the Gulf with record lengths of 6-12 months to study the tidal propagation. A northward increase in tidal amplitude is noticed from Daman (eastern side) and Diu (western side) and attains maxima at Bhavnagar. A similar trend is followed by the amplitude of the major tidal constituents, although there are discrepancies for that of the minor constituents. The non-tidal factor which influences the sea-level is the local wind, especially the alongshore component of wind. A positive correlation is obtained between the sea-level and the meridional component of wind at each location. Harmonic analysis of sea-level data shows that M2 is the major tidal constituent which propagates in a non-linear fashion inside the Gulf. Tides from two global tide models (MIKE21 and FES2014) have been compared with the measured data, which could be used for further prediction of the tides and sediment transport in the Gulf. The tide elevation derived from the MIKE21 model has further been used for the harmonic analysis of tide. The tides predicted using one-month data are up to 10% smaller than those predicted using the one-year data. The global tide model FES2014 data performs well with measured data for offshore locations, whereas it fails to predict the same for the inner Gulf locations. The study manifests the fact that to understand the dynamics of complex tidal areas, regional models should better be used than global tidal models.

Evolution of the semi-enclosed basins and surrounding coastal plains adjacent to the Pampean Region, Argentina

Violante R. A., Cavallotto J. L.

Polish Geological Institute Special Papers

2004

Vol. 11

59-70

The coastal plains adjacent to the Pampean region in eastern Argentina evolved during the Holocene in response to interaction between sea level fluctuations and different littoral dynamic factors in such a way that several sedimentary environments developed. Evolutionary stages can be synthesised in three periods: 1) the post-LGM transgression, when landward migrating coastal barriers extended on the present shelf under the effect of a dominant northward littoral drift; 2) the last stages of the transgression (between 8000 and 6000 years BP), when the rising sea flooded the Alto Marítimo (a pre-Holocene positive morphological feature which in previous times separated the course of the de la Plata river from the open sea), resulting in a new coastal configuration in which the presence of two headlands, Punta Piedras (in the north) and Villa Gesell (in the south), influenced the coastal processes so changing the original regional northward littoral drift into cell-type circulation systems; 3) between 6000 years BP and the present, when progradation processes characterised by barriers and beach ridges development dominated as a result of the sea level fall and an excess of sediment supply. As a result, coastal semi-enclosed basins located in between the headlands, such as Samborombón bay and Mar Chiquita lagoon, became the main depocenters where low-energy conditions (coastal lagoons, tidal flats and marshes) prevailed due to its isolation from the open-sea by the barriers and ridges. Interaction between southward migration of coastal environments associated to the northern headland and northward migration of those related to the southern headland was a very important process in shaping the present morphology of the area.