Journal Articles
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Item Managing a blackout : the consequences of an oil spill at sea /(Taylor & Francis, 2022-09-08) Shankar, Malini S.; Sivakholundu, K. M.The Ennore Oil Spill of 2017 triggered by a collision between two oil cargo vessels resulted in an environmental incident. This study is an attempt to cull the details from public domain and analyse the efficacy of the Government system to cope up with response. The information on events leading to the mishap indicates the suboptimal working conditions of seafarers prevailing on-board. The response activity drew negative publicity as the official communications were inconsistent. Besides declaring an under estimated quantum of oil spill, the perceived delay and inadequate resources seems to have aggravated the public sentiment. The episode of coastal spill clean-up came to close in two weeks with contributions from 30+ agencies of Government and industry along with 2000+ volunteers. The shoreline environment and fisheries activities returned to normalcy in three months’ time. Compensation to affected public was settled in a years’ time. However there is little information or unbiased evaluation of the episode available. An evaluation of such incidents will aid in addressing issues in future.Item Use of swath data in realtime navigation by pattern recognition(Marine Geodesy, 1989) Prabaharan, N.; Sivakholundu, K. M.A new method is proposed with the aim of reducing dead reckoning error (DRE) during multibeam echosounding survey in deep ocean. Bathymetric data is used in this method to estimate DRE in position fixing. This method can be activated at any desired interval to check the DRE accumulation in addition to available external navigation systems. A pattern recognition algorithm is developed to quantify the shift in position of a selected bathymetric feature that has been observed already once. This difference is used to correct the position fixing and navigation dataItem Surface current and wave measurement during cyclone Phailin by high frequency radars along the Indian coast(Current Science, 2015-02) John, Manu; Jena, B. K.; Sivakholundu, K. M.Cyclone Phailin originated in the east central Bay of Bengal (BoB) and crossed into the Indian mainland after traversing through the BoB. High frequency radar (HFR) operated by the National Institute of Ocean Technology could track the surface currents and high wave activity within its measuring limits. The radar data provide valuable information on the surface dynamics during the cyclone period. The HFR observations compare well with those of wave rider buoy. This opens up opportunities for observing the wave conditions during the cyclonic period over longer distances from the shore. This method is relatively more robust as HFR is less likely to be disrupted due to the passage of cyclones, unlike moored systems.Item Stability analysis and design of offshore submerged breakwater constructed using sand filled geosynthetic tubes(Procedia Engineering, 2015) Kiran, A. S.; Ravichandran, V.; Sivakholundu, K. M.Kadalur Periyakuppam (KPK) is a fishing village located 70 km south of Chennai in Tamil Nadu. The coastline of KPK was subjected to severe erosion due to high energy waves during Thane (2011), Nilam (2012) and Madi (2013) cyclones. The Tamil Nadu Fisheries department facilities located near the coast is subjected to damage as the coastline has receded by 45 m in the last few years following the severe erosion caused by cyclones. Since most of the erosion occurred after the storm waves hit the shoreline, sustainable option for shoreline protection would be to shift wave breaking to deeper depths. Based on numerical model studies and assessment of shoreline behaviour over two years, it is proposed to construct a submerged segmented breakwater. The submerged breakwater is proposed to be constructed at 4 m water depth up to a height of 3.5 m using sand filled geosynthetic tubes. Geosynthetic tubes shall be placed in a stacked manner with 2 tubes of 1.5 m high each at the bottom and a tube of 2.5 m height at the top accounting for height loss due to settlement. Design and stability checks are carried out by using available literature as no standard methods or design codes are available for design or stability checks for the geosynthetic tubes. The breakwater structure is checked for stability against sliding, overturning and bearing capacity. The geosynthetic tube material specifications such as tensile strength, ultra violet ray resistance, apparent opening size and fabric material are calculated using suitable design methods. The scouring, in front and behind the breakwater structure under prevailing wave conditions, is estimated for designing scour protection.Item Short term morphological evolution of sandy beach and possible mitigation: A case study off Kadalur Periyakuppam(Indian Journal of Geo-Marine Sciences, 2014-07) Sivakholundu, K. M.; Vijaya, R.; Kiran, A. S.; Abhishek, T.Item Seasonal variation in nearshore wave characteristics offCuddalore, Southeast coast of Tamil Nadu, India(Current Science, 2017-05) Jena, B. K.; Patra, Sisir K.; Joseph, K. Jossica; Sivakholundu, K. M.Wave data collected using wave rider buoy between January 2010 and January 2011 off Cuddalore coast, Tamil Nadu, India, have been analysed season-wise in this study. Wave steepness method was used for the separation of sea and swell wave parameters. Also parameters such as significant wave height of total wave, sea and swell (Hs , Hsw and Hss), zero crossing periods (Tz, Tsw and Tss) and mean wave directions (,sw and ss) have been studied. The study shows a distinct shift in sea wave direction of about 90 between June and October as well as November and February. Throughout the year, the predominant swell direction remained around 135. The contribution in total Hs by Hsw was 76% and the remaining 24% by Hss in the yearly cycle. The sea wave height was dominant by more than 90% during November to May. Regression analysis showed good positive Pearson’s correlation of 0.94 between Hs and Hsw; however, it was 0.65 between Hs and Hss. The maximum and significant wave heights of 5.7 and 2.7 m were recorded during cyclone Jal on 7 November 2010.Item Long term port monitoring system (PMS)(Indian Journal of Geo-Marine Sciences, 2014) Suseentharan, V.; Sivakholundu, K. M.; Jena, B.K.; Ravinder, M.; Balaji, R.NIOT has developed and operated a Port Monitoring System (PMS) at Gujarat Pipavav Port Limited (GPPL) to measure tide and current on real time. PMS consists of a pressure based tide gauge and a Horizontal Acoustic Doppler Current Profiler (H-ADCP) installed at 5 m depth w.r.t Chart Datum (CD). Tide, current speed and direction are measured and transmitted to NIOT server in real time and data is presented through web application after quality check (QC). The success and high utility of the data at GPPL has resulted in requests for similar installations in other ports (Mundra, Dahej, Hazira, Vizhinjam, Dhamra and IGCAR) which enabled NIOT to expand the PMS network. The system can be used with different communication links like GPRS, UHF and INSAT. Using GPRS link, the sensors can be configured remotely to change the sampling regime and communication interval. Being a modular design, the PMS has an option for integrating more sensors for met-ocean and water quality parameters depending on site or study specific requirement. The paper discusses the basic architecture, options that can be built and the experience gained during development, installation and operation in various site conditions.Item Estuarine channel stability assessment through tidal asymmetry parameters(Journal of Coastal Research, 2009-03) Sivakholundu, K. M.; Mani J. S.; Idichandy V. G.; Kathiroli S.In an estuarine channel the tidal asymmetry, sediment transport, and morphology are interconnected. To maintain a stable channel, we need to take tidal asymmetry into account. A relationship connecting tidal asymmetry and sediment transport rate has been used to evaluate the relative merits of channel modification through numerical simulations. Two criteria have been identified for ensuring the channel stability: (a) maintaining ebb dominance and (b) minimizing the spatial gradient in the net sediment transport function ⟨q⟩. Using these criteria for a test case, we have evaluated Hooghly estuary (east coast, India), where heavy sedimentation is experienced and a permanent solution is needed. The approach provides better insight into the sedimentation pattern in a semidiurnal tidal process in a shallow estuary with braided channels. Among the factors affecting tidal asymmetry, the relative phase difference (β) between M2 and M4 current constituents has a major influence and is thus responsible for the sedimentation pattern. Through numerical study it was found that a combination of deepened, uniform channel with enhanced ebb flow led to a favorable β, indicating less deposition.Item A program to compute the area of an irregular polygon on a spheroidal surface(Computers and Geosciences, 1998) Sivakholundu, K. M.; Prabaharan, N.Item A new archaeological find in the Gulf of Cambay, Gujarat(Journal of the Geological Society of India, 2002) Kathiroli, S.; Badrinarayanan, S.; Venkata Rao, D.; Rajaguru, S.; Sivakholundu, K. M.; Sasisekaran, B.Detailed underwater surveys carried out in the Gulf of Cambay, about 20 km west of Hazira, deploying side scan sonar and sub bottom profiler brought to light, the presence of a submerged palaeochannel traceable to a length of 9 km. Associated with this on either side are basement like features found in a grid pattern at water depths of 20-40 m. Sub-surface sampling carried out with dredge and grab sampler revealed stone artefacts, potsherds, hearth pieces, animal bones and human teeth embedded in fluvial sands and silts. In the upper part of the deposit, a carbonised wooden log was found and dated to around 9500 years BP by 14C method. Marine magnetic survey carried-out does not indicate the presence of any major metallic debrislobjects. This appears to be one of the early records of prehistoric human activity of early Holocene age in the marine environment of India.