Current Science

Jaya Kumar Seelam ¹, E. M. Yadhunath ¹, M. Jishad ¹, R. Gowthaman ¹, C. Rajasekaran ¹, P. S. Pednekar ¹

Affiliations
1 Ocean Engineering, CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, IN

Abstract

Equilibrium profile is one of the concepts in coastal geomorphology which is a result of the balance of destructive versus constructive forces. Two equilibrium beach profile models, viz. Bruun/Dean's twothirds power model and modified Bodge exponential model were used to analyse the measured post-monsoon (winter) beach profiles from three beaches in Goa having varying coastal morphology settings. The major factors that affect the equilibrium beach profile, viz. the median grain size (D₅₀) and the profile shape factor m, which are inversely proportional to each other, have been analysed for their application to the study site. Also, the variation of these two parameters with beach slope and grain size is studied. Longshore sediment transport rates (LSTRs) are estimated at these three beaches from the littoral environmental observations. LSTRs show that during winter months, the net transport is of the order of 10.83 × 10⁶ m³/year (southerly transport) and 9.02 × 10⁶ m³/year (southerly transport) respectively, at Candolim and Keri beaches, whereas it is about 0.62 × 10⁶ m³/year (northerly transport) at Miramar. This article discusses the methods used and results of measurements of beach morphology, LSTRs, analysis of equilibrium profiles and influence of various parameters related to equilibrium profiles.

Keywords

Equilibrium Beach Profile, Littoral Environment, Longshore Sediment Transport Rate, Sediment Scale Parameter, Slope Parameter.

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Sila Tripati ¹, R. Mani Murali ¹, Jaya Kumar Seelam ¹, Atula Kumar Pradhan ², Rudra Prasad Behera ¹, Richa Choudhury ¹

Affiliations
1 CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, IN
2 MGM Museum, Civil Lines, Raipur 492 001, IN

Abstract

The history of Odisha, lying on the east coast of India, is well documented from the Stone Age onwards. The evidences suggest that the ports of Odisha had contacts with the Arabs, Mediterranean countries and South Asia, as well as Southeast Asian countries. Khalkattapatna, a medieval port located on the banks of River Kushabhadra was discovered by archaeological excavations which suggest that between the 13th and 15th centuries it flourished and had contacts with Arabia and China, in addition to other countries. During recent explorations, a number of terracotta ring wells, stamped pottery, Chinese and celadon ware sherds, bricks and brickbats, and terracotta beads were found on the riverbank and in the waters of River Kushabhadra because of erosion of the north bank of the river. Remote sensing images of this region from 1977 to 2014 were analysed to delineate the river mouth and its course. Google Earth images of 2003 and 2011 were also referred to for an understanding of the migration of the northern bank of River Kushabhadra. This note describes the present state of the Khalkattapatna port, causes of erosion, change of north bank of the river course and its consequences.

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Jaya Kumar Seelam ¹, R. Mani Murali ¹, T. E. Baldock ²

Affiliations
1 National Institute of Oceanography, Goa 403 004, IN
2 University of Queensland, School of Engineering, St. Lucia, QLD 4072, AU

Abstract

Tsunami numerical model studies are mostly focused on inundation and run-up onto the coast. Fewer studies have been aimed at investigating the role of submarine canyons on tsunami heights, currents and run-up. The tsunami hydrodynamics in the vicinity of submarine canyons and ridges in the Palar-Cauvery region off the southeast coast of India on 26 December 2004 is considered in this study. Numerical modelling was carried out to study tsunami heights and currents in the vicinity of the submarine canyons as well as the variation of tsunami heights at 10 m water depth. Comparisons between the tsunami wave energy density at 10 m depth and the onshore run-up height observations showed good correlation for select locations, with the run-up heights being about 3% of the wave energy density. However, the local topography in the run-up zone also strongly influences the local run-up, which reduces direct correlations between run-up and nearshore tsunami height.

Keywords

Flow Velocity, Numerical Modelling, Run-Up Height, Submarine Canyons, Tsunami.

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