Journal Articles
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Item 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 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 Quantification of changes in seabed topography with special reference to Hansthal Creek, Gulf of Kachchh, India.(Journal of costal research, 1993-01) Pattanshetti, S.S.; Chauhan, Onkar.; Sivakholundu, K. M.Variations in the bathymetry in macrotidal Hansthal Creek between 1984 and 1950 along 14 closely spaced lines, are used to quantify the volumetric changes in seabed topography in terms of erosion/accretion. Two surfaces from the bathymetric data of 1984 and 1950 have been modelled. The profile wise comparison along the transects indicates a dynamic deformation due to distinct alteration in the shoreline and a shift in the channel course. The shoreline has retreated 650 and 450 m on the northern and southern banks respectively. The studies suggest scouring of horizontally deposited fine sediments (clays deposited in an antecedent depositional phase) in the Hansthal Creek due to existing dynamic equilibrium among (a) influence of physiography in amplifying the tidal range, (b) increased efflux due to contribution through inter-creek water movements, and (c) high magnitude currents. Magnitude of erosion in the creeks, particularly on the flanks, is much more than in the axial channel. The degree of the erosion reduces from the Hansthal Creek mouth to inland (area in the close vicinity of Little Gulf of Kachchh). During the last 34 years about 71.5 x 10 super(6) m super(3) from this creek during the course of the present study. Offshoreward movement of scoured sediments and their redeposition in the outer gulf as a fill in the paleo-channel is observed.Item Long term morphodynamic evolution of Kakinada bay using upscaling methods(Marine Engineers Review (India), 2020) Sharma, Garima.; Sivakholundu, K. M.; Patnaik, K. V. K. R. K.Kakinada Bay has evolved over the last century dynamically by the action of wind, waves, tides and currents. Formation of Hope Island and development of Coringa Mangroves are attributed to the hydrodynamic 'forcings' and sediment dynamics. This study aims to predict the future morphological development of Kakinada Bay for next 100 years. The morphological model was built up in the DELFT 3D package. Model setting parameters were fixed after analysing their effect on the simulation results. For reducing the computational time and effort for simulating long term morphological development, upscaling methods such as morphological acceleration factor (MORFAC) and morphological tide were incorporated in the morphological model. Morphological tide was formed using tidal constituents - M2, O1 and K1. The MORFAC value for this study was chosen as 30 after undergoing the sensitivity test analysis using Brier Score Skill (BSS) Score. The model was run for 19 years for hindcasting and 100 years for forecasting. In order to establish confidence in the model, it was calibrated and validated using hindcast modelling. The hindcast simulation results were used to match the simulated shoreline with satellite observed shoreline from year 1988 to 2000, and 2006 to 2013 and the results were in good agreement. It was observed that the south-western part of the bay has accreted more rapidly while south-eastern part of the bay has undergone slight erosion. Thereafter long term morphological model was run for 100 years to predict the future evolution of bay. Results of these simulations show the capability of the long term morphological model to predict the spatial and temporal geo-morphological changes.