Analysis Of Field Wave Data For Assessment Of Wave Transmission Coefficient Through Low Core Permeable Breakwater
V.B. Joshi, M. Phani Kumar and U.V. Purandare
Central Water & Power Research Station, P.O. Khadakwasla, Pune-411024.
Visakhapatnam Port on the east coast is a major port of India with all weather facilities. The southern breakwater was designed by keeping low core to accommodate 50 T concrete cubes for protection against southwest monsoon waves. It was reported that excessive ship motion at Offshore Tanker Terminal (OSTT) was causing difficulties in loading operations during SW monsoon. Three alternative measures were proposed by the project authorities. However, it was noticed by officials of CWPRS that the excess wave flux at OSTT was mainly due to transmission of wave through voids and gaps between 50 T blocks. A proposal of rubble lining on the lee side of the south breakwater to minimise wave disturbance at OSTT within acceptable tranquility was recommended after detailed hydraulic model studies at CWPRS, which was executed by VPT in 2001. Prototype wave data collected during the entire year 2002 have been analysed and compared with the model results, which confirms adequacy of the remedial measure. Efforts have been made in this paper, to present the detailed analysis of prevailing wave data, which provide relationship between the rate of wave transmission through breakwater with various wave and tidal parameters. The case study reveals that comprehensive analysis of model and prototype data as well as desk studies can develop confidence for design of new type of breakwater and execution of the works at major and minor ports.
Back
Analysis of formation of hard patches along the approach channel at new Mangalore Port
H.B. Jagadeesh, V.B.Joshi and U.V. Purandare
Central Water and Power Research Station, PO: Khadakwasla Research Station, Pune 411 024
Examination of formation of ‘hard patches' along the bottom of side slopes in the approach channel at New Mangalore Port was made by analysing the soil samples from these regions. The results of the grain size analysis indicated the presence of major percentage of fine sand in contrast to silty bed in the vicinity. The soil sample data from other region indicated that the source of fine sand is from the adjacent beaches. After the analysis of wave climate, shore bathymetry, it is estimated that beach sand is carried along the sandy fillets, which in turn is guided along the breakwaters into the approach channel. Presence of fine sand and clay alongwith silt in the approach channel increases the threshold shear stress, resistance to movement and density of the bed material, which accelerates the consolidation process, due to which the bed material turns into ‘hard patches'. These `hard patches' are difficult to dredge and cause difficulties for navigation. Remedial measures like outward flaring of the breakwaters, construction of groins, sandtraps and submerged spurs are suggested.
Back
Development of a mini fishery harbour at Thottappally
Kunhimammu Paravath and P.I.Sheik Pareeth
Harbour Engineering Department, Thiruvananthapuram, Kerala – 695 009
Thottappally coast is an open seacoast with an artificial outlet called Thottappally spillway that is almost closed for the entire annual season. It is a good fishing region in Alappuzha District. Therefore, it is imperative to develop this region into a fishery harbour. This paper highlights the details of investigation, surveys, model studies, planning, design and estimation for the development of a mini fishery harbour at Thottappally. The detailed project report for the development of harbour is prepared based on the studies. The economic evaluation of the project is also carried out.
Back
Numerical model studies for the proposed fishing harbour at Mahe
V. Sundar¹, S.A. Sannasiraj¹, V. Sriram¹, G.V. Chitra Devi¹, R. Balaji¹ and P.I.Sheik Pareeth²
¹Department of Ocean Engineering, Indian Institute of Technology Madras,Chennai-600 036
²Chief Engineer, Harbour Engineering Department, Thiruvananthapuram Kerala-695 009
The tranquility conditions of proposed breakwater alignments for the formation of the fishing harbour at Mahe for the maximum prevailing wave heights approaching from different directions were investigated through a numerical model. The appropriate alignment of the breakwaters was arrived based on the numerical results. From the analysis of the wave data, the annual sediment transport rates along the considered coastal area were also estimated based on well-established methods. The details of wave conditions, littoral drift, tranquility conditions for different alignments and the results are presented in this paper.
Back
Degradation of coral reefs in Gulf of Mannar, southeast coast of India - with special reference to land use/land cover changes: a remote sensing and GIS approach
M. Thanikachalam¹ and S. Ramachandran²
¹Department of Civil Engineering, Sona College of Technology, Salem-636 005,
²Department of Ocean Development, Anna University, Chennai- 600 025, Tamil Nadu
Coral reef and land use/land cover maps were prepared using multi-date remote sensing data to assess the current status and changes of coral reefs and land use/land cover in Gulf of Mannar. The changes in land use/land cover indicate that the major changes occurred in crop land, fallow land, agriculture plantation, forest plantation, scrub land, sandy area and tanks. Data also reveals a reduction of 25.52 km² in coral reef lost over a period of ten years, due to changing land use/land cover and other anthropogenic activities along Gulf Mannar coast. This study also reveals that in Gulf of Mannar, nearly 67.2% of the corals were dead, 13.1% coral reefs are directly removed by coral mining and remaining 19.6% were live corals.
Back
Rehabilitation of rubblemound breakwater by providing a wide toe-berm
I.Z. Poonawala, M.D. Kudale, A.A. Purohit and S.P. Kulkarni
Central Water and Power Research Station, Khadakwasla, Pune-411 024.
A concept of providing a wider toe-berm to the rubblemound breakwaters was successfully used for rehabilitation of damaged breakwaters. In the conventional rubblemound breakwater, the structure is provided with a small toe having a berm width of about 3 m to 5 m, which acts as a seat to the armour layer. However, in the wide toe concept, a toe having a berm width of about 15 m to 25 m is provided, which reduces the wave energy attacking the armour layer and thereby reduces the required stable weight of armour units. The concept of a breakwater with a wide toe-berm is very useful in rehabilitation of damaged rubblemound breakwaters. The seaward portion of the damaged mound can be utilised as a wide toe for the rehabilitation works. Studies indicated that a toe-berm of about 20 m width just at the low water level and having stone weight of 1/5 to 1/10 of the armour units of conventional breakwater, reduces the required weight of stable armour units by more than 50%. The use of wide toe-berm concept in the rehabilitation of damaged breakwater reduces the cost of rehabilitation of breakwater by about 30% to 40% as compared to conventional breakwater.
Back
Model studies for the proposed fishing harbour in Rameswaram
V. Sundar¹, P.K. Suresh¹, A. Selvarajah², M. Jayapalan²
¹Dept of Ocean Engg, IIT Madras, Chennai – 600036,
²Institute of Hydraulics and Hydrology, Poondi-602 023.
Rameswaram is an Island located along the south east coast of Tamilnadu. A fishing harbour is proposed to be constructed due to high potential for fishing activity. The layout that was arrived was verified based on numerical model studies. In addition, it was finalised after validating with physical model studies. The effect of post harbour construction on the shoreline was also assessed. The details of the analysis are presented and discussed in the paper.
Back
Impounded solution for Kandla Port
P.V.Chandramohan
Gouri Sadan, Azad Road, Kaloor, Kochi - 682017, Kerala
In locations of high tidal ranges, the natural choice is to put up berths inside an impounded dock. Along the Indian coast, the tidal ranges are found to increase towards the north. History has it that three docks were constructed at Bombay. Docks were put up at Calcutta also. These were all put up by the British during their time. In free India, docks at Haldia and Bhavanagar were put up in the seventies and sixties. They were designed by foreigners. But this was not done later in other locations with higher tidal ranges. The paper deals with the proposal for an impounded dock near Kandla where the tidal range is 7 m.
Back
Archaeological remains of the ancient harbours along the west coast of India: a legacy of our maritime heritage
A.S. Gaur, Sundaresh and Sila Tripati
National Institute of Oceanography, Dona Paula, Goa-403004
The maritime activity has played a vital role in the emergence of well-developed civilizations around the world during mid-Holocene period. Cultural interaction, exchanges of technology, trade and commerce led the human society to reach at present day height. However, this development is the result of a well-organized town planning, construction of jetties and harbours in the past. The archaeological explorations during last one century brought to light a large number antiquity related to ancient Indian harbours and maritime activities.
Archaeological excavations brought to light a jetty at Kuntasi in Rajkot district of Gujarat, dating back to Harappan period. The site is located on the river-bank and it is believed that during high tide boats were reaching the site. It is generally believed that Lothal on the head of Gulf of Khambhat, was an international trade centre during Harappan period. Marine archaeological explorations by the Marine Archaeology Centre of NIO brought to light the existence of harbours at Dwarka, Bet Dwarka, Somnath, Vijaydurg, Sindhudurg, Gopakapattana and Poompuhar. Identification of ancient harbour is based on the discovery of archeological evidences like stone anchors, stone structures etc.
Back
Development of transhipment container terminal at New Mangalore Port
Kiran G. Shirlal¹, Bhaskar Dharani¹ and T.R. Bhatt²
¹Department of Applied Mechanics and Hydraulics, NIT, Karnataka, Surathkal, Srinivasnagar-575 025
²Retired Chief Engineer, NMPT, Panambur
The desire for self sufficiency, savings and expansion of trade has seen larger container vessels coming into service. This has given rise to establishment of Transhipment Terminals all over the world. Major portion of Indian container traffic is transshipped through some neighbouring foreign ports, thereby draining huge amount of foreign exchange. Hence, there is need for establishing a Transhipment Terminal in India. Authors have put forth the case of New Mangalore Port as a possible location for establishing such a terminal.
Back
Estimation of design wave heights over the north Indian Ocean using satellite data
Raj Kumar, Jignesh Kshatriya, Abhijit Sarkar and Vijay K. Agarwal
Meteorology & Oceanography Group, Space Applications Centre (ISRO), Ahmedabad 380 015
The knowledge of ocean waves is of great importance to the engineers for design of offshore structures, their operations and ship routing. The radar altimeter onboard satellites is one of the useful sensors being used for estimation of surface wind and wave parameters. For the present study, 10 years of TOPEX radar altimeter data have been analysed and 50 and 100 year return values of wave height and wind speed using satellite data have been estimated. Since, the satellite data is not available at each and every location, the estimates have been carried out in 2 0 x 2 0 bins. The Gumbel distribution has been fitted to the satellite wave data in each bin. The estimated values of extreme wave height are found to be higher in the Western Arabian Sea with values of the order of 8-9 m, whereas the extreme values in the Bay of Bengal region are approximately 5-6 m.
Back
Evolution of berthing structures in Kandla
P.V. Chandramohan
Kandla Port Trust, Gandhidham, Gujarat-370 201
Port of Kandla is located in a creek. The location is subjected to severe environmental conditions. From the early fifties, berths were being put up on one bank of the creek. Since the berths were built one after the other, in a straight line, the changes were quite visible. The technology available during the fifties imposed severe constraints in the design. So these structures were vulnerable to environmental calamities. As time passed, technology developed. The design engineer was presented with improved construction techniques and design tools. The paper reviews the various structures over a half century; from structural and functional angles.
Back
Stability of core-loc armoured rubble mound breakwater
V. Sundar, S.A. Sannasiraj and R. Balaji
Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai-600 036
A detailed experimental study was carried out to check the stability of mound breakwater with CORE-LOC as the armour layer proposed for Pawas bay on the west coast of India. After a comprehensive review of the different alternatives for the breakwater trunk and head sections, the modified sections were tested for the specific wave climate and water depth conditions in a wave flume. The breakwater sections were tested for the different fractions of significant wave heights and their stability was assessed in terms of damage levels. The details of the review of the design, breakwater models, instrumentation, testing procedure and results are discussed in this paper.
Back
Harbour area information system through GIS
Suresh Nayak, G.S. Dwarakish and S.G. Mayya
Department of Applied Mechanics and Hydraulics, National Institute of Technology Karnataka, Surathkal, Srinivasanagar – 575 025
The use of Geographical Information System (GIS) in planning of Port will be beneficial from the construction, expansion and maintenance point of view. GIS plays its own role in fulfilling the objective of upgrading the ports more precisely and timely. GIS will be useful tool to depict various locations and its alignment, surface profiling, estimating the dredging volume, vessel traffic management system etc. New Mangalore Port (NMP) at Panambur, Dakshina Kannada coast, Karnataka, along the west coast of India is the study area. This port was declared as the 9th major port of India on 4 th May 1974. The objective of the present study is to create the GIS database and to develop a module for New Mangalore Port Trust (NMPT) using Geo-Media Professional 5.1 GIS software and Visual Basic 6.0 (V.B.6.0). Both spatial and non-spatial available data related to NMP are collected from NMPT, minor irrigation department, port sub-division etc. The present module gives the online information about the past and present construction activities, location of entrance channel, turning circle, different coastal and other structures within and adjacent to port area, and other harbour area information. Thus, handling the entire activity of a port aided by the GIS and V.B.6.0 application opens up a new frame in the path of development.
Back
Complexities of dredging at Kandla Port Trust
G. S. Rao
Kandla Port Trust, New Kandla, Gujarat
The port of Kandla is located on the west bank of Kandla Creek at the eastern end of Gulf of Kutch along the west coast of India. From the pilot station of Kandla Port, the total length of Navigational Channel is about 27.7 km. Out of the above channel, a critical reach of only about 2.3 km. is having very less depths. The present Approach channel called the Sogal Channel (in which the critical reach exists) is dredged through out the year. A minimum navigable depth of about 6.0 m below C.D. was achieved in stages by Oct.2004 from that of 3.7 m available in 1984 when the Sogal channel was commissioned for navigation of ships. By carrying out the required maintenance as well as capital dredging from the year 2000 onwards, Kandla port has already achieved a draft of 11.5 m.by 31/10/2004 and the port has planned to increase the present draft from 11.5 m. to 13.5 m. in phases by 2006-07.
Back |
