Faculty Publications
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Item Integrated coastal zone management plan for Udupi coast using remote sensing, geographical information system and global position system(SPIE spie@spie.org, 2008) Dwarakish, G.S.; Vinay, S.A.; Dinakar, S.M.; Pai, B.J.; Mahaganesha, K.; Natesan, U.Coastal areas are under great pressure due to increase in human population and industrialization/commercialization and hence these areas are vulnerable to environmental degradation, resource reduction and user conflicts. In the present study an Integrated Coastal Zone Management Plan (ICZMP) has been developed for Udupi Coast in Karnataka, along West Coast of India. The various data products used in the present study includes IRS-1C LISS-III + PAN and IRS-P6 LISS III remotely sensed data, Naval Hydrographic Charts and Survey of India (SOI) toposheets, in addition to ground truth data. Thematic maps such as land use/ land cover map, bathymetry map, shoreline configuration map, transportation and drainage network maps, GPS survey map, CRZ map, contour map, DEM, inundation map, critical erosion area map were prepared. A Coastal Vulnerability Index has also been calculated for the study area to know the resistance of study area to sea level rise and is demarcated into four categories; Very high, High, Moderate and Low vulnerability, and a vulnerability map has been prepared. The results of the present study are encouraging. Some of the specific conclusions of the study are; about 50% study area is prone to erosion, river mouths along study area show shifting tendency towards south, and the beaches along the Udupi Coast are maintaining dynamic equilibrium. Coastal Zone Information System (CZIS) has been developed through V.B.6.0 using results of various data analysis. © 2008 Society of Photo-Optical Instrumentation Engineers.Item Coastal vulnerability assessment of the future sea level rise in Udupi coastal zone of Karnataka state, west coast of India(2009) Dwarakish, G.S.; Vinay, S.A.; Natesan, U.; Asano, T.; Kakinuma, T.; Venkataramana, K.; Pai, B.J.; Babita, M.K.Udupi coast in Karnataka state, along the west coast of India, selected as a study area, is well known for sandy beaches, aquaculture ponds, lush greenery, temples and major and minor industries. It lies between 13°00?00?-13°45?00? north latitudes and 74°47?30?-74°30?00? east longitudes, the length of the coastline is 95 km, and is oriented along the NNW-SSE direction. It is vulnerable to accelerated sea level rise (SLR) due to its low topography and its high ecological and touristy value. The present study has been carried out with a view to calculate the coastal vulnerability index (CVI) to know the high and low vulnerable areas and area of inundation due to future SLR, and land loss due to coastal erosion. Both conventional and remotely sensed data were used and analysed through the modelling technique and by using ERDAS Imagine and geographical information system software. The rate of erosion was 0.6018 km2/yr during 2000-2006 and around 46 km of the total 95 km stretch is under critical erosion. Out of the 95 km stretch coastline, 59% is at very high risk, 7% high, 4% moderate and 30% in the low vulnerable category, due to SLR. Results of the inundation analysis indicate that 42.19 km2 and 372.08 km2 of the land area will be submerged by flooding at 1 m and 10 m inundation levels. The most severely affected sectors are expected to be the residential and recreational areas, agricultural land, and the natural ecosystem. As this coast is planned for future coastal developmental activities, measures such as building regulation, urban growth planning, development of an integrated coastal zone management, strict enforcement of the Coastal Regulation Zone (CRZ) Act 1991, monitoring of impacts and further research in this regard are recommended for the study area. © 2009 Elsevier Ltd. All rights reserved.Item Physical model studies on wave transmission of a submerged inclined plate breakwater(2009) Rao, S.; Shirlal, K.G.; Varghese, R.V.; Govindaraja, K.R.This paper examines the results of physical model studies conducted in a monochromatic wave flume, to evaluate the wave transmission characteristics of a submerged plate breakwater consisting of a fixed plate of 0.50 m length and 0.003 m thickness. The model was oriented at varying inclinations and submergence. The influence of wave steepness, relative depth, relative submergence and angle of inclination on wave transmission was analysed. It was found that the horizontal plate is effective for short waves with steepness parameter higher than 5×10-3 in relative depth grater than 0.21. The plate oriented at an angle of inclination of 60° is found to be effective for the entire ranges of wave parameters considered for the study and it reduces the wave height by about 40%. © 2009 Elsevier Ltd. All rights reserved.Item Neuro-fuzzy based approach for wave transmission prediction of horizontally interlaced multilayer moored floating pipe breakwater(2011) Patil, S.G.; Mandal, S.; Hegde, A.V.; Alavandar, S.The ocean wave system in nature is very complicated and physical model studies on floating breakwaters are expensive and time consuming. Till now, there has not been available a simple mathematical model to predict the wave transmission through floating breakwaters by considering all the boundary conditions. This is due to complexity and vagueness associated with many of the governing variables and their effects on the performance of breakwater. In the present paper, Adaptive Neuro-Fuzzy Inference System (ANFIS), an implementation of a representative fuzzy inference system using a back-propagation neural network-like structure, with limited mathematical representation of the system, is developed. An ANFIS is trained on the data set obtained from experimental wave transmission of horizontally interlaced multilayer moored floating pipe breakwater using regular wave flume at Marine Structure Laboratory, National Institute of Technology Karnataka, Surathkal, India. Computer simulations conducted on this data shows the effectiveness of the approach in terms of statistical measures, such as correlation coefficient, root-mean-square error and scatter index. Influence of input parameters is assessed using the principal component analysis. Also results of ANFIS models are compared with that of artificial neural network models. © 2010 Elsevier Ltd. All rights reserved.Item Comprehensive physical model study on wave transmission at plate structure(CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2011) Shirlal, K.G.; Rao, S.; Varghese, R.V.Investigators are increasingly concentrating their focus of research on coastal protection which is shifting from the hard measures to eco-friendly solutions with optimal usage of construction materials. A structure located near the water surface is known to be effective in bringing down the wave activity behind it, since; the energy of the waves is concentrated in the region close to the surface. This paper explains the comprehensive experimental study to evaluate the transmission coefficients (Kt) of various configurations of submerged plate structures. Kt for various plate configurations such as single plate, twin plate and combined plate are obtained. It is found that a single plate inclined at 60° to the horizontal is generally effective i. e. Kt ? 0.6 to a large extent. However, the twin and combined plate structures improved the performance. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Development of concrete armoured protected breakwater structure(CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2011) Rao, M.; Rao, S.; Shirlal, K.G.The present work involves the physical model study of stability of conventional single breakwater and the reef protected breakwater, constructed with concrete cube as an artificial armour unit. Regular waves of wide ranging heights and periods are used. The tests are carried out for different spacings between the two structures (X/d = 2.5-13.33) and for different relative heights (h/d = 0.625-0.833) and relative widths (B/d = 0.25-1.33) of the reef. It is observed that a reef of width (B/d) of 1.0-1.33 constructed at a seaward distance (X/d) of 6.25-8.33 exhibits a transmission coefficient (Kt) of 0.38-0.708, wave dissipates energy and protect the breakwater optimally. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Variation of transmission coefficient and mooring forces with wave steepness on horizontal interlaced multilayered moored floating pipe breakwater with three layers(2011) Rajappa, S.; Pramod, K.; Hegde, A.V.; Rao, S.The paper presents the results of a series of physical model scale experiments conducted for the study of the transmission characteristics and mooring forces of horizontal interlaced, multi-layer, moored floating pipe breakwater, part of which have been presented in conferences. The studies are conducted on physical breakwater models having three layers of PVC pipes, wave steepness, Hi/L (Hi is incident wave height and L is incident wave length) varying from 0.01384 to 0.0661, relative width, W/L (W is width of breakwater) varying from 0.4 to 2.65 and relative spacing, S/D = 3 (S is horizontal spacing of pipes and D is diameter of pipe). The transmitted wave height is measured and data gathered is analyzed by plotting non-dimensional graphs depicting the variation of Kt (transmission coefficient) with Hi/L for values of d/W (d is depth of water) varying between 0.082 to 0.276 and Kt with W/L for values of d/W varying between 0.082 to 0.221. It is observed that Kt marginally decreases as Hi/L increases for the range of d/W between 0.082 and 0.221, considered in the present study. The maximum wave attenuation achieved with present breakwater configuration is 68%. The variation of measured mooring forces are analyzed by plotting non-dimensional graphs depicting fs/?w2 and fl/?W2 (fs and fl are the forces in the seaside and leeside moorings per unit length of the breakwater, ? is the unit weight of sea water) as a function Hi/L for various values of d/W. The mooring force parameter (fs /?W2) increases with an increase in wave steepness (Hi/L) for a range of d/W values studied. It is observed that for d/W = 0.082, maximum force parameter attained was 2.11E-04, and for d/W = 0.276 maximum force parameter was 6.88E-04. A similar trend is observed for leeside side force parameter. Hence, it clearly indicates the influence of d/W on f/?W2. © 2011 CAFET-INNOVA technical society. All right reserved.Item Wave steepness and relative width: Influence on transmission coefficient of horizontal interlaced, multilayered, moored floating pipe breakwater with five layers(2011) Rajappa, S.; Hegde, A.V.; Rao, S.; Channegowda, V.This paper presents the results of a series of physical model scale experiments conducted to determine the transmission characteristics of a horizontal interlaced, multilayered, moored floating pipe breakwater. The studies are conducted on physical breakwater models having five layers of PVC pipes. The wave steepness (H i/gT 2, where H i is incident wave height, g is acceleration due to gravity, and T is time period) was varied between 0.063 and 0.849, relative width (W/L, where W is width of breakwater and L is the wavelength) was varied between 0.4 and 2.65, and relative spacing (S/D, where S is horizontal centre to centre spacing of pipes and D is the diameter of pipes) was set equal to 2. The transmitted wave height is measured, and the gathered data are analyzed by plotting nondimensional graphs depicting the variation of K t (transmission coefficient) with Hi/gT 2 for values of d/W (d is depth of water) and of K t with W/L for values of H i /d. It is observed that K t decreases as H i /gT 2 increases for the range of d/W between 0.082 and 0.139. It is also observed that K t decreases with an increase in W/L values for the range of H i /d from 0.06 to 0.40. The maximum wave attenuation achieved with the present breakwater configuration is 78%.Item Development of prediction models for hydrodynamic performance of semicircular breakwater(2012) Aggarwal, A.; Gope, V.K.; Managiri, S.S.; Hegde, A.V.Breakwaters are structures built to protect harbors, shore areas, basins, and other areas from the fury of sea waves. They create calm waters and provide for the safe mooring and handling of ships, as well as protection to harbor facilities. The main function of a breakwater is the formation of an artificial harbor. Of late, certain new types of breakwaters have been constructed to cater to the tranquility requirements of managing marine traffic in ports. The semicircular breakwater (SBW) is one such new type of breakwater. The semicircular breakwater possesses a round top and, thus, offers more stability against the action of waves. It is expected that the SBW will be well suited as an offshore breakwater designed to protect beaches from coastal erosion. A number of experiments were conducted on scaled-down physical models of SBW for different values of parameters such as wave height H, wave period T, spacing of perforations on the seaside, etc. (radius of breakwater and diameter of perforations were kept constant), and data were collected. The paper presents the prediction models/equations for hydrodynamic performance characteristics such as reflection coefficient and relative wave runup, using the data obtained by a regression approach in MATLAB.Item Study on performance of Savonius rotor type wave energy converter used in conjunction conventional rubble mound breakwater(Elsevier Ltd, 2014) Bikas, G.S.; Ramesh, H.; Hindasageri, V.In the present study the performance characteristics of a wave energy converter used in conjunction with conventional rubble mound breakwater is investigated using physical model studies. Savonius rotor type converter is used in the present study. The rotor is placed in front of the breakwater towards seaward side can cause substantial wave attenuation and thereby reduce the impact on the breakwaters apart from generating electricity. Regular waves of wide ranging heights and periods are considered in the present study. Tests are carried out for different spacing between the breakwater and the wave energy converter (X/d=10 to 40) and for two depth cases viz. shaft of the rotor at SWL (z=0) and rotor fully submerged case (z=-55 mm). The dead weight loading (shaft power) capacity for the rotor is also optimised in the present study. From the experimental study, it is observed that at a distance of X/d=22.5 to 30 and for submerged case (z=-55 mm) the rotor is found to be most efficient. It results in a wave height attenuation of 15-33%. © 2014 Elsevier Ltd.