Indian Journal of Geo-Marine Sciences

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Longshore Currents on a Meso-Tidal Beach of Goa, India - Measurements and Improved Formulae


Affiliations
1 Naval Physical and Oceanographic Laboratory, Thrikkakara, Kerala – 682 021, India
2 Academy of Scientific and Innovative Research, Ghaziabad – 201 002, India
3 CSIR-National Institute of Oceanography, Dona Paula, Goa – 403 004, India
4 Cochin University of Science and Technology, Cochin – 682 022, India
 

Field experiments in the surfzone were conducted on a meso-tidal beach stretch between Sinquerim and Baga off Goa on India's central west coast. Surfzone waves and currents were measured using an array of seabird wave and tide gauges and Aanderaa RCM9 current meters. Rip currents were observed prominently in this stretch with increased intensity during the ebb tide. Six longshore current prediction equations are tested for their suitability in this region. The Longshore Current (LSC) estimated using these equations showed a wide range of Mean Absolute Percentage Error (MAPE) and Scatter Index, and the correlation coefficients were also found to be less than 50 %. Hence, these equations are further modified by including the alongshore wind shear component, and the LSC was re-estimated to study the variations in current along the Candolim beach. It was observed that the correlation coefficients improved up to 64 % for most of the equations.

Keywords

Longshore Currents, Rip Currents, Surfzone, Waves.
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  • Reniers A & Battjes J, A laboratory study of longshore currents over barred and non-barred beaches, Coast Eng, 30 (1) (1997) 1-21.

  • Guza R & Thornton E, Variability of longshore currents, Coast Eng Proc, 1 (16) (1978) p. 43. DOI: https://doi.org/10.9753/icce.v16.43

  • Putnam J A, Munk W H & Taylor M A, The prediction of longshore currents, Trans Am Geophys Union, 30 (1949) 337-345.

  • Saville T, Model studies of sand transport along an infinitely straight beach, Trans Am Geophys Union, (31) (1950) 555-556.

  • Brebner A & Kamphuis J W, Model tests on the relationship between deep water wave characteristics and Longshore currents, Coast Eng, (9) (1964) 191-196.

  • Galvin C J & Eagleson P S, Experimental study of longshore currents on a plane beach, (US Army Coastal Engineering Research Center, Washington D C), 1965, pp. 198. https://apps.dtic.mil/sti/pdfs/ADA345211.pdf

  • Galvin, Experimental and theoretical study of longshore currents on a planar beach, Ph.D. Thesis submitted to Department of Geology and Geophysics, Massachusetts Institute of Technology, Cambridge, 1963, pp. 185. http://hdl.handle.net/1721.1/58355

  • Inman D & Quinn W, Currents in the surf zone, Coast Eng Proc, 1 (2) (1951) p. 3. https://doi.org/10.9753/icce.v2.3

  • Harrison W, Empirical equation for longshore current velocity, J Geophys Res, 73 (22) (1968) 6929-6936.

  • Longuet-Higgins, Longshore currents generated by obliquely incident sea waves: 2, J Geophys Res, 75 (33) (1970) 6790-6801.

  • Komar P D & Inman D L, Longshore sand transport on beaches, J Geophys Res, 75 (30) (1970) 5914-5927.

  • Lanfredi N W & Framiñan M B, Field Study and Prediction of Longshore Currents, Argentine Coast, J Coast Res, 2 (4) (1986) 09-417.

  • Nummedal D & Finley R J, Wind-generated longshore currents, Coast Eng Proc, 1 (16) (1978) 1428-1438.

  • Hanes D M, Longshore Currents, In: Treatise on Geomorphology, 2nd edn, edited by John F S, (Academic Press, Elsevier), 2022, pp. 83-99

  • Kumar V S, Chandramohan P, Kumar K A, Gowthaman R & Pednekar P, Longshore currents and sediment transport along Kannirajapuram Coast, Tamilnadu, India, J Coast Res, 16 (2) (2000) 247-254.

  • Hameed Shahul T S, Baba M & Thomas K V, Computation of Longshore currents, Indian J Geo-Mar Sci, 15 (2) (1986) 92-95.

  • Chandramohan P, Nayak B U, Anand N M & Sanil Kumar V, Field measurement on longshore current variation between Ratnagiri and Mangalore, west coast of India, In: Proceedings of Eighth Conference of International Association of Hydraulic Research, CWPRS, Pune, 1992, pp. 271-282.

  • Yadhunath E M, Jayakumar S, Jishad M, Gowthaman R, Rajasekaran C, et al., Surfzone currents at Candolim and Miramar beaches of Goa, India: measurements and comparisons, Indian J Geo-Mar Sci, 43 (7) (2014) 1210-1216.

  • Chandramohan P, Sanil Kumar V & Jena B K, Rip current zones along beaches in Goa, west coast of India, ASCE J Waterw Port Coast Ocean Eng, 123 (6) (1997) 322-328.

  • Antony M, Wave refraction off Calangute beach, Goa, with special reference to sediment transport and rip currents, Indian J Geo-Mar Sci, 5 (1976) 1-8.

  • Larson M, Hoan L X & Hanson H, Direct Formula to Compute Wave Height and Angle at Incipient Breaking, J Waterw Port Coast Ocean Eng, 136 (2) (2010) 119-122.

  • Moore G W & Scholl D W, Coastal sedimentation in northwestern Alaska, (US Atomic Energy Commission, TEI No. 779), 1961, pp. 43-65.


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  • Longshore Currents on a Meso-Tidal Beach of Goa, India - Measurements and Improved Formulae

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Authors

E M Yadhunath
Naval Physical and Oceanographic Laboratory, Thrikkakara, Kerala – 682 021, India
J K Seelam
Academy of Scientific and Innovative Research, Ghaziabad – 201 002, India
P S Pednekar
CSIR-National Institute of Oceanography, Dona Paula, Goa – 403 004, India
R K Rajive
Cochin University of Science and Technology, Cochin – 682 022, India
R Gowthaman
CSIR-National Institute of Oceanography, Dona Paula, Goa – 403 004, India

Abstract


Field experiments in the surfzone were conducted on a meso-tidal beach stretch between Sinquerim and Baga off Goa on India's central west coast. Surfzone waves and currents were measured using an array of seabird wave and tide gauges and Aanderaa RCM9 current meters. Rip currents were observed prominently in this stretch with increased intensity during the ebb tide. Six longshore current prediction equations are tested for their suitability in this region. The Longshore Current (LSC) estimated using these equations showed a wide range of Mean Absolute Percentage Error (MAPE) and Scatter Index, and the correlation coefficients were also found to be less than 50 %. Hence, these equations are further modified by including the alongshore wind shear component, and the LSC was re-estimated to study the variations in current along the Candolim beach. It was observed that the correlation coefficients improved up to 64 % for most of the equations.

Keywords


Longshore Currents, Rip Currents, Surfzone, Waves.

References