Temporal variation of upwelling during Pre-monsoon season off East Coast of india
A.D. Rao, Sujata Dash* and S.V. Babu
Centre for Atmospheric Sciences, Indian Institute of Technology, Delhi-110016
*Defence Terrain Research Lab., Metcalfe House, Delhi-110054
A three-dimensional numerical model is developed and used to study the coastal upwelling processes off the east coast of India. Upwelling, a phenomenon that brings subsurface waters to the surface, may be visualized as the response of coastal ocean to pure wind-stress forcing. The model is designed to represent coastal ocean physics by resolving surface and bottom Ekman layers as realistically as possible. The prognostic variables are the three components of the velocity, temperature, salinity and turbulent energy. The governing equations together with their boundary conditions are solved by finite-difference techniques. Experiments are performed to investigate the fluctuations in upwelling and thermal response to variable wind-stress. It is known from the observational study that the upwelling process is prevalent in surface waters in May along the east coast of India. The model is forced with satellite derived real time mean weekly wind-stress forcing of different weeks of May, representing pre-monsoon season for the year 2000. The results are found to be qualitatively in good agreement with the satellite inferred SST imageries.
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Beach dynamics of an open coast on the West Coast of india
S. Jaya Kumar¹, N.S.N. Raju² and R. Gowthaman¹
¹Ocean Engineering Division, National Institute of Oceanography, Dona Paula, Goa – 403004
²National Institute of Oceanography, Regional Centre, Visakhapatnam.
In order to study the daily beach dynamics at an open beach in Goa, field investigations were carried out on the beach profiles, breaking wave parameters and long-shore currents for one month each during pre-monsoon and post-monsoon periods. Three transects on the Calangute beach, Goa, spaced about 250 m apart were selected. Pre-monsoon breaking wave heights were observed to be between 0.4 and 1.3 m and the wave period between 5 and 11 s, whereas, the post-monsoon breaking wave heights were between 0.35 and 1.4 m with the periods ranging between 8 and 15 s. Pre-monsoon long-shore currents were stronger (max. 1 m/s) and varying in direction compared to post-monsoon (max. 0.66m/s) wherein the direction was predominantly north. Post-monsoon foreshore slopes were found to be mild and the berms wider compared to the pre-monsoon beaches. Inter-tidal beach sediments in the pre-monsoon period were coarse compared to post-monsoon sediments. Average estimated long-shore sediment transport rate in the study region indicates that the gross long-shore sediment transport was high during pre-monsoon compared to the post-monsoon. The net transport was southwards and about 0.013x10 6 m 3 /year during the pre-monsoon and it was northerly and about 0.007x10 6 m 3 /year during the post-monsoon. Whereas, the average gross transport rate was 0.02x10 6 m 3 /year during the pre-monsoon it was 0.014x10 6 m 3 /year during the post-monsoon.
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Numerical modeling of tidal circulation in the Gulf of Kachchh including Kandla creek, west coast of India
G. K. Jena, P. C. Sinha, A. D. Rao and Indu Jain
Centre for Atmospheric Sciences, Indian Institute of Technology Delhi – 110 016
A two-dimensional depth averaged numerical model having a resolution of 750 m x 750 m has been developed to study the tidal flow in the Gulf of Kachchh. A separate 2D fine resolution model has also been developed for the Kandla creek having a resolution of 75 m x 75 m. These two models are coupled to compute the tidal circulation in the Gulf of Kachchh including Kandla creek. The model dynamics and basic formulations remain the same for both these models. The model is fully non-linear and uses a semi-explicit finite difference scheme to solve the basic hydrodynamic equations on a staggered grid. The model neglects horizontal diffusion and wind stress terms in the momentum equations and is applied to the gulf region. It is a barotropic model, based on shallow water equations to simulate the sea surface elevation and circulation in the analysis area. The flow in the gulf is strong due to high tidal range. The tide in the gulf is mainly represented by a semi-diurnal M 2 constituent.
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Beach profile studies along the South West Coast of India
Kunhimammu Paravath
Harbour Engineering Department, Thiruvananthapuram, Kerala – 695 009
The beaches have been in existence over a geological time scale and are moulded, eroded and remoulded by nature. Dynamic changes have always occurred in this fragile strip of land. There are various types of construction like major and minor ports, breakwaters and seawalls along the coastline. To study the morphological changes, a study of beach profiles along Kerala coast has been conducted. Ten years data on beach cross-section profiles were available for the present study. The results of the detailed analysis and impacts of the marine structures on the profile assessed are presented in this paper. The net loss/ gain of land was computed.
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A model for shoreline management
M.V. Ramanamurthy, M.S.Bhat and B. R.Subramanian
ICMAM-PD, DOD, Chennai 601302
Coastline has been a focus for a variety of activities including industry, recreation and fisheries. These national economic assets have developed and flourished despite constant changes in the physical characteristics of the coast, sometimes lead, often unintentionally, to adverse effects on both adjoining and distant stretches of coastline. For example, the construction of Madras Port in 1876, was the prime cause of shoreline changes along the adjoining coast. It is estimated that an area of 260 ha of land has been lost between 1893 and 1955 and that an area of 30 ha of land between 1980 and 1989. Overall loss between 1893 and 1989 has been estimated to be in the order of 350 ha. The cost of the land alone lost to the sea is of the order of 40 million USD. The work carried out by ICMAM-PD (2003), along this stretch of the coast clearly indicated a need for a well-defined plan that seek to treat the shoreline and the defence requirements in a more integrated, sustainable and strategic manner. Here we highlight the impacts of Madras harbour development on the adjoining coast and effectiveness of short term mitigation measures planned and executed by the government agencies to protect the fragile coastline of Chennai (Madras, India). This paper describes a simple and a very useful model that illustrates various steps to be followed while adopting a plan for Shoreline Management, particularly for coastal defence.
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Design wave prediction along the coast of India
M.D. Kudale, C.N. Kanetkar and I.Z. Poonawala
Central Water and Power Research Station, Khadakwasla, Pune-411 024.
Ocean wave is the most important environmental parameter influencing the design and operational efficiency of marine structures. Particularly, the severe storm waves, which establish the magnitude of the design waves, are important for designing marine structures. Underestimation of extreme storm waves can lead to failure of coastal/offshore structures, whereas overestimation results in uneconomical design. Also, it is important to consider the normal sea wave conditions, which govern the operational efficiency of these structures. The design and operational wave conditions are evaluated by statistical analysis of extreme wave data and the normal sea wave data, respectively. Extreme wave analysis was carried out for various sites along the Indian coast using the available wave data. The sources of data, methodology adopted for analysis and the design wave conditions derived for typical sites have been presented in this paper.
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Simulation of warm water dispersion in coastal environment
B.M. Patil¹, A.L. Kothandaraman², C.N. Kanetkar¹, L.R. Ranganath¹, R. Manivanan¹
¹Central Water and Power Research Station, Khadakwasla, Pune - 411 024
²Indira Gandhi Centre for Atomic Research, Kalpakkam - 603 102
In coastal areas seawater provides an inexhaustible source of cooling water and also a sink for disposal of heated water from power station. For optimizing the efficiency of power generation, it is essential to locate the intake/outfall to minimise the recirculation of warm water discharge under the prevailing environmental site conditions. Moreover, if the site is in the region of high littoral drift, adverse impact on the shoreline due to the intake/outfall should be avoided. In order to optimise the locations of intake/outfall for the proposed nuclear power station at Kalpakkam, mathematical model studies were carried out for dispersion of warm water discharges under different environmental conditions. The studies revealed that the alternative of discharging the warm water from the power station in deep sea at about 750 m from shore towards south of the existing MAPS outfall would be suitable for minimising recirculation and its adverse impact on the shoreline.
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Shoreline changes along the Poompuhar and Tranquebar coasts of Tamil Nadu
P.K. Suresh, D. Panneerselvam, M. Jayapalan and G. Nagaraj
Institute of Hydraulics and Hydrology, Poondi-602 023, Tamil Nadu
Poompuhar and Tranquebar located along East Coast of Tamil Nadu are very important places from historical point of view. The river Cauvery empties into the Bay of Bengal near Poompuhar. Tranquebar is famous for its ancient Danish connections .The coast is highly sensitive to seasons. Observations of the beach width changes from 1982 were collected. Data on beach width were compiled and analysed for different seasons. The details of fluctuations in beach width with respect to time are detailed in the paper.
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Mathematical modeling study of design parameters for submarine pipeline at Gulf of Kachchh
P. Chandramohan, D.P. Rao and P. Senthil Pandi
Indomer Coastal Hydraulics (P) Ltd., Chennai.
A study was undertaken to estimate the design waves along the proposed submarine pipeline corridor in Gulf of Kachchh. The software CEDAS was used for wave hindcast and design wave analysis. The synoptic information on past cyclones were derived from IMD reports. From the deep water waves, the design waves along the pipeline corridor were estimated using numerical wave refraction study.
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Prediction of extreme wind speed for Kuwait
S. Neelamani and Layla Al-Awadhi
Coastal Engg. and Air Pollution Dept., Environmental and Urban Development Division, Kuwait Institute for Scientific Research, P.O. Box : 24885, 13109 SAFAT, KUWAIT
Kuwait is a coastal country with a total of about 660 km coast. The extreme wind speed for different return periods is essential for the design of tall structures, for extreme value prediction of waves in the ocean etc. Measured wind data from 1962 to 1997 from the Kuwait Airport is collected and used for the prediction of expected wind speeds for return periods of 50 years, 100 years etc. The analysis is carried out both for 10 minute average wind speed and gust speed. Log Normal, Weibull, Gumbel and Fretchet distributions are used for the extreme value predictions. Gumbel distribution is found to fit better for the measured wind speed in Kuwait International Airport. For a return period of 50 years and 100 years, the 10 minute average wind speed is predicted as 65.8 mph and 70.9 mph respectively. For the same return period, the gust speed is predicted as 89.39 mph and 96.98 mph respectively. These predictions will be useful for designing the land and ocean structures in the bay area of Kuwait and for establishing the extreme rate of sand transport from the desert area into the Arabian gulf.
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Influence of crest width on hydraulic performance of submerged reef
Kiran G. Shirlal, Subba Rao and Venkata Ganesh
Department of Applied Mechanics and Hydraulics, NITK, Surathkal, Karnataka
In the present experimental investigation, an attempt has been made to study the hydraulic performance of a submerged reef of height. The reef, which is a homogeneous pile of armour units without a core, breaks the steeper waves and dissipate a major portion of their energy. The wider reef can decrease the wave transmission further. This paper investigates the influence of varying reef crest width on the wave transmission at the submerged reef breakwater.
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Wave run up and run down studies on Berm breakwater with reduced armour weight
Subba Rao, K.Subrahmanya, V.R.Chandramohan, B.Radheshyam and K.Balakrishna Rao
Department of Applied Mechanics & Hydraulics, National Institute of Technology Karnataka, Surathkal, SRINIVASANAGAR – 575 025.
A step in the path of invention is always accompanied by a wish for optimization. Similarly, breakwaters which mainly aims at breaking up of the waves for providing tranquility conditions, in their optimizing phase has led to the evolution of Berm breakwaters. The design philosophy of berm breakwaters aims at optimizing the structure not only with respect to wave load but also possible yield from an armour stone quarry, which can be characterized as supply–based design. In the present study the static stability of the berm breakwater model with berm width of 60 cm and 20% reduced armour weight than that of conventional mound breakwater formula has been tested. The variations of non-dimensional run up values (R u /H o ) and the rundown values (R d /H o ) with deep-water wave steepness (H o /gT 2 ) are brought under the study area. A decrease in wave run up and run down with increase in wave steepness has been observed.
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Study of littoral transport along Dakshina Kannada coast, Karnataka
Subba Rao, Kiran G. Shirlal, Radheshyam B. and Mahaganesha K.
Department of Applied Mechanics & Hydraulics, National Institute of Technology Karnataka,Surathkal, Srinivasnagar – 575 025
The area selected for the present study is the coast along the Dakshina Kannada district. It contains the natural features as well as manmade structures. The natural features are river mouths and open coasts. The manmade structures are the New Mangalore Port (NMP) breakwaters, breakwaters at river mouths of Netravathi-Gurupur and Udyavara. The sediment accretion and erosion pattern adjacent to these breakwaters are analysed. The sediment grain size analyses of the beach sand near the river mouths and along its open beaches are conducted. The sediment trend matrix analysis was also carried out and sediment movement paths are drawn. After analysing all the above it can be concluded that littoral drift along the Dakshina Kannada coast is negligibly small and the chances for any major problems of coastal stability influenced by littoral drift are remote.
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Modelling wave surge interactions
G.K. Sen¹ and M. Chatterjee²
¹School of Oceanographic Studies, Jadavpur University, Kolkata 700 032
²Basanti Devi College, Kolkata 700 029
A mathematical model has been used for simulating wave surge interactions along the West Bengal Coast, during storm surge events following cyclonic storms. Model outputs include ocean currents and sea surface elevations and wave height at each grid point.
The amplified waves due to the surge wave interactions cause maximum damage to the coastline: increasing coastal erosion, damaging embankments, imposing additional risk to harbours and ports. In this context, particularly, for coastal zone management excercises, the study undertaken is very relevant.
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Estimation of wave characteristics during hurricane in the Hoian area, Central Vietnam
Le Dinh Mau¹, V. Sanil Kumar², G.N. Nayak³ and S. Mandal²
¹Department of Marine Physics, Institute of Oceanography, Nhatrang, Vietnam
²Ocean Engineering Division, National Institute of Oceanography, Dona Paula, Goa–403004
³Department of Marine Sciences, Goa University, Goa–403 206
The data of hurricanes crossed the coastline from 14 0 N to 17 0 N, in the vicinity of the Hoian coastline, from 1945 to 2003 were extracted from the National Weather Service, USA. The features such as velocity of forward motion and wind speed were considered. Radius of maximum wind speed was estimated using the Saffir-Simpson scale. The maximum significant wave height within the storm and its associated spectral peak period were estimated using the Young's model. Empirical expressions relating wave height, maximum wind speed and wave period during hurricane were derived. The computed results from Young's model were compared with the hurricane wave prediction techniques of SPM (1984). The design wave height for the hurricane condition for different return periods was obtained by fitting a two-parameter Weibull distribution. The study indicates that in all, 69 hurricanes occurred in the vicinity of the Hoian coastline during 1945 to 2003 (with an average of 1.2 times a year), among which include 36 typhoon with maximum wind speed (V max )>33 m/s, 20 tropical storm with 17 m/s< V max <33 m/s, and 13 subtropical storm with V max <17 m/s. Occurrences of hurricanes were mostly in September (26.1%), October (30.4%) and November (13%). In general, radius of maximum wind speed of all hurricanes was 34 km. The design wave height was 11.7 m for 1 in 100 year return period.
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Sustainable beach protective measure along Digha-Shankarpur coast on bay of Bengal
Gupinath Bhandari
School of Oceanographic Studies, Jadavpur University, Kolkata-700032
Coastal erosion and accretion is a natural process influenced by wave and littoral environment of ocean dynamics for a particular stretch of beach. The natural sand budgeting due to ocean/ coastal dynamics may result erosion, accretion or may create stable beach stretch. The anthropogenic activities along with the natural process may create disaster of a particular area due to paucity or surplus of sand to the beach. Analysis of coastal dynamics and the impact of sea defence structures on the littoral process, for proper planning and designing of erosion protective measures, involve a large number of parameters of coastal dynamics. The field measurements of most of these parameters are difficult and prohibitive in cost. However, mathematical model appears to be a useful tool for this analysis and design. Such a model has been developed to study the beach erosion and provide sustainable protective measures along Digha coast and presented in this paper.
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Wind and wave climatology along the Eastern Coast of the Mediterranean
Ron Schreier¹ and Matti Weiss²
¹Rafael Ballistic Center, P.O. Box 2250 Haifa, 31021, Israel.
²Israel Meteorological Service, Beit Dagan, Israel.
Wind and wave measurements are carried out constantly since 1994 on the eastern coast of the Mediterranean at the ports of Haifa, Hadera and Ashdod.
In order to study the daily and multi-seasonal behavior of the sea waves, a spectral analysis of the wind and wave data was done. In addition, an effort has been done to discover events of high waves and weak winds (swell).
The results show annual and daily variations in the average wave's height. The annual amplitude is twice that of the daily amplitude (about 4 m and 2.2 m respectively).
The wind behavior is only a bit different – strong winds (higher velocities than 10 m/s) occur in frequencies of 24 and 12 hours, while winds of 4 m/s occur in low frequencies. Analyzing the wind directions shows that north western winds appear once in 12 hours while eastern winds appear (only in Haifa) once in 24 hours with velocities of half the maximal ones.
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Coastline change monitoring: comparison of georeferenced graphical Cadastry with data from multiple sources
K.K. Ramachandran, M.R. Kannan, K. Rajesh, John Mathai and M. Samsuddin
Centre for Earth Science Studies, Akkulam, Thiruvananthapuram-695 031
Coastlines undergo changes with time due to natural as well as man-made developmental activities. Regular updation of spatial coastline information is of vital importance to any maritime state. Cumulative changes over a period of time manifests itself into long-term changes of coastline. With the latest technologies of remote sensing, soft photogrammetry and GIS, it has become possible now to depict and analyse coastline changes more precisely with time. Thus, the study essentially focuses on:
(i) Methodology for accurate georeferencing of cadastral maps (village maps) depicting the survey plots (parcels) as per revenue land-holding records based on precisely defined ground control points using differential GPS without compromising on its planimetric accuracy
(ii) Using orthocorrected high resolution satellite images (IKONOS) and aerial photographs in addition to Survey of India (SoI) topographic maps to delineate the shoreline positions, and
(iii) GIS based quantification of shoreline change with time (1926 – 2003).
These emerging trends in geomatics were utilized to study a small coastal sector (~12.5 km) along the Malappuram District in Kerala. Data products used in the study are the cadastral maps in 1:3960 scale (1926), SoI topographic maps of 1:50,000 scale (1969), aerial photographs (scanned to photogrammetric accuracy with each pixel to ground resolution ~21 cm) and 1 m BW IKONOS image. IGS corrected Principal Reference Points were established by continuous static DGPS observations using dual frequency geodetic Leica receivers and network adjustment was performed for the GCPs occupied with GPS to derive submeter positional accuracy. Digital image/photo-grammetric processing and georeferencing of the satellite image and aerial photos was carried out using ERDAS Imagine suite. Digitization and collation of the vectorised layers were realized in the ArcGIS environment. Precluding the disparate spatial resolution of the SoI topographic maps, the resultant multi-date coastlines successfully demonstrated the depiction of micro-level changes along the coast.
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Deltaic shoreline evolution
Snigdha Ghatak¹ and G. K Sen²
¹Geological Survey of India, Central Region, Seminary Hills, Nagpur-440 006
²School of Oceanographic Studies, Jadavpur University, Kolkata-700 032
Ghoramara Island located 2.75 km. north of the northern tip of Sagar Island, at the mouth of Hoogly estuary, Sundarban Delta, West Bengal shows a continuous erosional trend over the last 30 years. This is evident from GIS based analysis of time series data of 1968-69 (SOI Toposheet), 1988 (LISS II digital data), 1995 & 1999 (LISS II, hard copy FCC) of the island. With the need to assess the impact of local sea level/water level conditions and other coastal variables on this vulnerable coastal tract, a spatio – temporal correlation based model for Ghoramara Island is developed. This model accounts for the pattern of change in coastal configuration with the tide gauge computed local sea level/water level rise data adopting an indirect form - process approach. The correlation was implemented as algorithms or a set of equations within GIS environment and the best-correlated results were applied to generate the terrain data. Recasting the output values within the GIS environment, results for the coastal configuration of Ghoramara for different time intervals as well as different local sea level rise scenarios could be generated. For example, the projected configuration of Ghoramara Island in say, next 10, 20, 30 years with different sea level rise scenarios i.e 2.9 mm/yr., 3mm/yr., 3.1 mm/yr etc. are determined taking the year 1999 configuration as the reference frame. Good match between the projected year say, 1999 (projected from 1995 or say, 1988) with the original digitized data set of 1999 indicates that local scale sea level conditions in presence of other estuarine variables viz. tide, wave, current etc. has a noticeable contribution in shaping the configuration of the Ghoramara Island. This opens up the potentiality of the model for undertaking near future management plan.
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Morphodynamic state of Mudga beach, West Coast of India
P. T. Hanamgond
Department of Geology, G.S. Science College, Tilakwadi, Belgaum – 590 006.
Morphodynamic processes on a monthly, seasonal and annual time scale operating along the Mudga beach, located in Karwar taluk of Uttara Kannada district, was studied during November 1988 to December 1991. The study brings out morphology, texture and sediment movement across and along the beach. The volumetric study reveals that the beach has gained a net 71 m 3 m -1 material through continuous or episodic erosion/ accretional patterns. It is clear from volumetric study at four selected study sites that, the beach experiences progressive accumulation of sediment towards north. The beach exhibits the occurrence of clay deposit during monsoon and postmonsoon seasons which has played a major role in modifying the beach dynamics.
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Monitoring of a lagoon system in Kuwait
K.A. Rakha and F. Al-Hulail
Kuwait Institute for Scientific Research, P.O. Box 24885, 13109 Safat, Kuwait,
The khiran area south of Kuwait is currently being developed. The existing lagoon system is being expanded and houses will be constructed along the lagoons. This project will be completed over five phases. This paper provides hydrodynamic data collected before and after the completion of phase A1. The RMA finite element package was used to model the hydrodynamics and the flushing of the lagoons. The model was validated using the measured data for the pre- and post-construction stages. The model showed that the flushing of the existing lagoons was not affect by the construction activities. The end of the dredged lagoons however showed reduced flushing as compared to the existing lagoons.
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Shoreline oscillations caused by port - methods of assessment and evaluation
M.V. Ramana Murthy, B.R. Subramanian and J.S. Mani¹
ICMAM-PD, Department of Ocean Development, NIOT Campus, Chennai – 601302
¹Department of Ocean Engineering, IITM, Chennai – 600 025
Ennore Port, located north of Chennai Port, was constructed in 1999 to meet the increasing demand of cargo. It is in operation since 2001 with coal as major cargo. Structures constructed along the East Coast of India, result in accretion on south and erosion on north due to net northerly drift. To protect downdrift coast from erosion, shoreface nourishment was taken up on north of the Ennore port in 2000. For assessing the impacts of port and performance of protection measures on adjacent coastline, understanding of coastal morphology, more specifically, shoreline behavior is required. Various methods adopted to analyse the shoreline data and their limitations are discussed. An improved method of combining Remote Sensing, GPS and GIS techniques was used to evaluate the shoreline changes, caused by construction of the port. Performance of beach fill is assessed based on the beach profile data.
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Tidal currents as feeders of the river Indus flux into the macrotidal Gulf of Kachchh, India
O.S. Chauhan¹, S. Jaya Kumar¹, A.A. Menezes¹, J. Suneethi¹, N. Shradha¹, A.S. Rajawat², S.R. Nayak², M.V. Ramanamurthy³ and B.R. Subramanian³
¹National Institute of Oceanography, Dona Paula, Goa 403 004.
²Space Application Centre, P.O., SAC, Ahmedabad – 380015.
³ICMAM Project Directorate, Department of Ocean Development, Chennai.
Tide synchronous abundance of total suspended matter (TSM), currents and hydrodynamic modeling during September of 1999 have been evaluated to decipher source to sink pathways in the macrotidal Gulf of Kachchh. Despite being located in the arid region with low rainfall (50 cm y<sup> -1</sup> ) and insignificant fluvial input, gulf waters are enriched in suspended matter. The TSM distribution is highly dynamic and changes with prevalent tidal conditions. Generally, all along the northern flank, the gulf waters remain turbid irrespective of tidal conditions. Moreover, TSM is showing inland reducing trend in the inner regions of the gulf. We have also observed significant amount of suspended matter across shelf dispersal of TSM in the central region, particularly during low and high tide conditions. Derived from the spatial variations in TSM, prevalent hydrography and clay mineral abundance, an advection of flux of river Indus into the gulf by flood tide currents is deduced.
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Assessment of wave modeling results with buoy and altimeter deep water waves for a summer monsoon
K. Sudheesh, P. Vethamony, M.T. Babu and S. Jayakumar
National Institute of Oceanography, Dona Paula, Goa-403 004.
A second-generation offshore spectral wave model has been applied to simulate wind waves over the north Indian Ocean during May–August 2000 using 6 hourly NCEP re-analysis wind data. The significant wave height (SWH), wave period and mean wave direction derived from the model have been compared with moored buoy and TOPEX altimeter data. As the accuracy of simulated wave parameters depends on the accuracy of winds, the NCEP re-analysis winds have been compared with buoy winds and an assessment is made to this effect. The data of deepwater buoys off Goa, Kochi, and Chennai have been utilised for comparison. It is difficult to get sufficient collinear altimeter points with modelled output, and therefore, all the altimeter SWH values are organised in 0.75~' x 0.75~' size boxes and compared the average value in each grid with those of model output and buoy SWHs. Comparison of model and buoy wave parameters during the summer monsoon shows that model results agree closely with the buoy measurements (Example, for Kochi SWHs, bias = 0.888 and correlation coefficient (g) = 0.923). Higher winds, of the order of 15-18 m/s, off Goa and Kochi and 10-12 m/s off Chennai, and wave heights, of the order of 3.5-4.5 m observed during 5-7 June 2000 are due to a low-pressure system present at that time, and the model is quick in reflecting this rapid change, and it is a clear evidence of the model capability. Wave heights, in general, are higher in the Arabian Sea than the Bay of Bengal during June to August, but nearly the same in May.
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