Varikoden, H.; Roja, C.; Revadekar, J.V., and Milind, M., 2020. Rainfall variation in major river basins in India and the association with the Indo-Pacific Oceans. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 1-6. Coconut Creek (Florida), ISSN 0749-0208.

The summer monsoon rainfall is the major water source for most parts of India and people depend on this water source for their livelihood. The rainfall during this season is highly variable over space and time. The rainfall during the southwest monsoon period is the main source of flow discharge in most of the rivers in India. In the present study, we made an attempt to explore the variability and trends in rainfall over the Ganges, Brahmaputra, Godavari and Krishna river basins. Northern river basins show a negative trend indicating the decrease of rainfall and increasing trends are observed in peninsular river basins. The Brahmaputra river basin shows a significant decreasing trend (-0.16 mm day^-1 decade^-1). Moreover, the variability in multi-time scale is also different for different basins. Among all the river basins considered in the study, the Brahmaputra river basin registered high average rainfall (15.11 mm day^-1 with a standard deviation of 2.23 mm day^-1) and the Krishna river basin the least (3.57 mm day^-1 with a standard deviation of 0.87 mm day^-1). Further, the large scale teleconnection of the rainfall with individual river basins has also been assessed. The Ganga river basin is one of the largest river basins and this region is highly influenced by the Arabian Sea and the west Pacific Ocean (Nino 3.4 region). However, the Brahmaputra basin does not show much connection with Sea Surface Temperatures (SST) over the west Pacific Ocean, the Arabian Sea or the Bay of Bengal. The rainfall in the Godavari and Krishna river basins have more influence on SSTs over the central Pacific Ocean.

Rajasree, B.R. and Deo, M.C., 2020. Future geomorphologic changes under the changing climate. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas.Journal of Coastal Research, Special Issue No. 89, pp. 7-14. Coconut Creek (Florida), ISSN 0749-0208.

The evaluation of shoreline changes for a few decades into the future can be done by using historical satellite imageries or numerical shoreline modelling. This work investigates the use of neural networks for this purpose as an additional method. Its advantage is that it provides a more flexible method of data fitting than the linear regression involved with the use of the imageries. Further, this work proposes the use of futuristic data of wind and waves in place of historical ones in the numerical modelling so that the effect of changing climate can be accounted for. Three different types of shoreline stretches representing continuous and discontinuous coastlines along the central west coast of India are considered and shoreline erosion or accretion rate for future 36 years is evaluated using satellite imageries, as well as neural networks and numerical modelling. The latter is based on projected wind and wave data derived from a regional climate model. The future predictions from neural networks were more close to those from the numerical modeling than the direct extrapolation from the past satellite imageries and hence it is suggested that they might act as supplementary to the former when future changes are to be predicted. The networks can also be used to cross-check the numerical predictions as well as the predictions based only on satellite imageries as per the common practice.

Tejas, D.M.; Gnanaseelan, C.; Rashmi A.K., and Deepa, J.S., 2020. Indian Ocean warming trends and forcing mechanism with emphasis on northeastern tropical Indian Ocean. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 15-19. Coconut Creek (Florida), ISSN 0749-0208.

Subsurface temperature variability in the northeastern Tropical Indian Ocean (TIO) is addressed in this study. The recent decade witnessed strong positive trends in the warming of subsurface waters of Indian Ocean. On the other hand the net heat flux in to the ocean is showed a negative trend in the last decade citing the oceanic process as the primary cause of temperature variability and trends. The present study is focused on understanding the temporal evolution of the subsurface temperature structure of the northeastern TIO from the latter part of the twentieth century. Long term trends and time series are examined to see whether they result from low-frequency variability. It is seen that, strong warming in the northeastern TIO is closely related with phase change in the decadal oscillation of temperature as well as equatorial Indian Ocean dynamics. Associated circulation over this region supports the findings. The equatorial Kelvin wave after mid 2000s also seems to play a crucial role in the evolution of subsurface temperature patterns.

Anand, P.; Anubhav, C.A., and Albert, P.I., 2020. Observation and modeling of low saline water flow through Gulf of Mannar during December 2016. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 20-25. Coconut Creek (Florida), ISSN 0749-0208.

Indian Ocean is unique as it features the reversal of currents in relation to the monsoonal winds. During the north-east monsoon season (November-February), the East Indian Coastal Current (EICC) is known to flow round Srilanka into the South Eastern Arabian Sea (SEAS) which transports low saline waters from the Bay of Bengal (BoB). Till now, due to lack of observational data along the Gulf of Mannar (GoM), it is not evident, whether part of the water that flows from BoB is passing through the Palk Strait/Bay and GoM to reach SEAS. There are two schools of thought existing, one is that, the flow exists through this passage. Efforts have been made to prove this using simulation studies. The second thought is that the Pamban Pass as well as the Adam's Bridge act as barriers for this passage of water. To study the subject in detail, CTD observations during December 2016 along GoM and west coast of India are utilized. Analysis shows that, the surface waters along transect of GoM is lower in salinity (33 psu) than that of SEAS (34 psu) with the lowest surface salinity along the easternmost transect. Different case studies, carried out using high resolution (10 km) Princeton Ocean Model (POM), suggested that the flow exists through the GoM. The signature of low saline water (33.2 psu) in this region is also well matched with that of the observations. The study concludes that, the flow through the Palk Bay/Strait and GoM have a distinct role in bringing the water from the Bay to SEAS.

Ananya, K.; Anant, P.; Chowdary, J.S., and Gnanaseelan, C., 2020. Sensitivity of subsurface processes of equatorial Pacific Ocean to the heat and momentum fluxes: A case study of 1997-98 El Niño. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 26-31. Coconut Creek (Florida), ISSN 0749-0208.

The influence of accurate heat and momentum fluxes on 1997-98 El Niño simulation is investigated using Geophysical Fluid Dynamics Laboratory (GFDL) ocean model Modular Ocean Model version 5 (MOM5). Control experiment (CTRL) is carried out by using surface forcing from the CORE2 inter-annual flux, whereas sensitivity experiment (OAERA) is carried out by using heat fluxes from WHOI Objectively analysed air-sea fluxes (OAFlux) data and momentum fluxes from ERA-interim (ERA-I). Both experiments are carried out for a common period of 1985-2009. These experiments revealed that the strength of inter-annual variability is sensitive to accuracy of the forcing. In particular, the sensitivity experiment displayed better simulation of 1997-98 El Niño features such as developing and peak phases. The strength of Niño indices (mainly Niño 3 and Niño 3.4) in OAERA is comparable to EN 4/ORAS 3 more than CTRL. Further analysis reveals that throughout the equatorial Pacific Ocean upper ocean temperature anomaly evolution during the developing to peak phase is improved in OAERA, which is further confirmed by the mixed layer temperature anomaly tendency (TAT) evolution. Detailed analysis of dynamical feedback contribution to TAT indicates that in CTRL, thermocline and zonal advection feedbacks are overestimated and their temporal evolution is inconsistent compared to ORAS 3, whereas these feedbacks are consistent in OAERA, leading to better simulation of Niño indices. Our study concludes that accurate heat flux and momentum flux forcing can improve the simulation of Niño indices and equatorial Pacific upper ocean temperature anomaly associated with the strong El Niño 1997-98.

Gayathri, R.; Ranga Rao, V.; Damodara Rao, V., and Kumaresan, D., 2020. A 3D numerical modelling study on temperature and salinity structure along coastal waters of Kochi during northeast monsoon In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 32-38. Coconut Creek (Florida), ISSN 0749-0208.

The coastal waters of Kochi are one of the marine ecosystems with high anthropogenic influence. The land based influx through the inlets influence the abundance and the dynamics of the nutrients. As the advection and the mixing of the nutrients are governed by the hydrodynamics of the region, a 3D model was setup to investigate the dynamics of various hydrographical parameters such as flow field, temperature, salinity, and density, during the Northeast monsoon. MIKE-3D model successfully captured the near shore dynamics and advection-dispersion of the temperature and salinity. The model results and the field observation were within comparable limits, indicating an acceptable model configuration. The results pointed out that the wind stress and the tides were the dominating mechanisms in determining the circulation characteristics. The influence of tidal currents in dispersing the land based inputs was evident from the simulations. Moreover, the model setup was able to capture the variability and the vertical distribution of temperature and salinity.

Mohapatra, S. and Gnanaseelan, C., 2020. Warming trends in the central equatorial Indian Ocean and the associated coupled feedback processes. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 39-45. Coconut Creek (Florida), ISSN 0749-0208.

The recent increasing trends in the tropical Indian Ocean (TIO) temperature have strong impact on the regional as well as global climate variability. In this work we studied the changes in the boreal summer monsoon winds and the associated monsoon currents on modulating the surface and subsurface temperature of the equatorial Indian Ocean. The reduction in the meridional sea surface temperature (SST) gradient and strengthening of zonal SST gradient over the Indian Ocean reduced the northward propagation of south-westerly wind, thereby enhancing the surface westerlies over the equator. The strengthened surface westerlies increased the equatorial downwelling Kelvin waves and deepened the thermocline. The present study unravels the causes for the observed confinement of strong SST trend over the central equatorial Indian Ocean (CEIO) even though surface westerlies and the associated downwelling extend upto the eastern equatorial Indian Ocean (EEIO). In contrast to the CEIO surface warming, EEIO experienced strong subsurface warming at thermocline. Our analysis suggests that the upper ocean stratification plays an important role in the observed warming trend of both CEIO surface and EEIO subsurface. The eastward equatorial currents bring warm salty water from Arabian Sea and WEIO towards east and warms CEIO, however the high saline surface water is found to sink in the EEIO, thereby warming the subsurface instead of surface. The composite of temperature anomaly for the period 1978-2002, the period of warm Pacific Decadal Oscillation, shows patterns similar to temperature trends, which clearly suggests the dominance of decadal variability on the TIO temperature trends.

Imranali, M.M.; Mitra, A.K.; Waters, J.; Martin, M.J., and Rajagopal, E., 2020. Impact of Altika Sea Level Anomaly data on variational assimilation system. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 46-51. Coconut Creek (Florida), ISSN 0749-0208.

Altimeter data provide measurements of dynamic topography over the global ocean and is useful for the constraining numerical ocean modeling systems through data assimilation. In this study, sensitivity experiments are carried out to understand the relative impact of Sea Level Anomaly (SLA) extracted from satellite data on a variational assimilation system for the month of August 2013. A first experiment, without assimilation of SLA observations is called CNTR while a second experiment assimilating Ka band Altika SLA into the variational assimilation system is called ALTK. Both experiments assimilated all other observations such as surface and in situ observations of temperature and salinity as well as sea ice concentration. To understand the impact of altimeter observations, we computed the root mean square difference (RMSD) of analyzed temperature from both experiments and showed that the maximum impact is over the Indian Ocean, North Atlantic Ocean and tropical Pacific Ocean regions due to the large displacement change applied to the thermocline depth in the ALTK experiment. We also note that the impact of altimeter on analyzed temperature is over different depths. Finally, the analyzed SSH has less root mean square error (RMSE) with respect to the altimeter observations for ALTK experiment than CNTR experiment over the global ocean and shallow water over the Indian Region (60-105°E, 5-40°N).

Mahanty, M.M.; Latha, G.; Sridhar, P.S.S.R., and Raguraman, G., 2020. Estimation of direction of arrival of biological sound using acoustic vector sensor array in shallow water off Chennai. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 52-57. Coconut Creek (Florida), ISSN 0749-0208.

The primary objective of this study is to estimate the direction of arrival (DOA) of biological sound by using an acoustic vector sensor array, deployed in the shallow waters off Chennai during the period 30^th August-14^th September, 2016. A vector sensor measures the scalar acoustic pressure along with acoustic particle velocity in three orthogonal directions. Based on the spectrogram analysis, Terapontidae fish chorus is identified in distinctive patterns associated with daily timing and frequency content throughout the recording. The chorus is species-specific with the spectral peak frequency extended over 0.6-1.5 kHz in each day after dusk, and indicates these sound signals are associated with spawning. The single call duration is about 0.35-0.45 s, and comprised of a series of pulses ranging from 35-40. By considering the single call as a sound source from the recorded Terapontidae fish chorus, the DOA is determined based on conventional beamforming technique with respect to dominant frequency of that particular sound source, and estimated both azimuth and elevation using vector sensor array components. The study clearly shows the application of the vector sensor array, and can be useful to estimate source localization of the biological sound and their movement in the marine environment in future work.

Malarkodi, A.; Latha, G., and Srinivasan S., 2020. An experimental study of passive time reversal process of underwater acoustic communication in shallow waters of the Bay of Bengal. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 58-62. Coconut Creek (Florida), ISSN 0749-0208.

Underwater acoustic communication in shallow water is a challenging task due to channel fading, Inter Symbol Interference (ISI) and noise caused by time varying multipath channel. Passive time reversal is a computationally inexpensive technique to mitigate ISI introduced by the channel. This paper describes the effect of passive time reversal technique and its spatial and temporal focal properties to reduce channel fading and inter symbol interference in the received communication signals in a highly reverberant channel. Performance of passive time reversal communications is evaluated for a passive time reversal experiment conducted off Bay of Bengal during September 2017. A single acoustic projector generated linear frequency modulated probe signal and BPSK data packets at a baud rate of 1000 bps with the frequency band of 4 kHz at the center frequency of 11 kHz. These signals were received at a range of approximately 3 km from the source by the vertical hydrophone array of three hydrophones. Since the side lobe leakages are the causes of ISI and bit error for communications, the effectiveness of the temporal focusing is measured by the peak to side lobe ratio of the phase conjugated pulse. The performance of the communication was measured by calculating the BER. The experimental results provide further evidence that the passive time reversal technique can be considered as a good option for reliable underwater communication in a complex acoustic channel.

Suseentharan, V.; Arunraj, K.S.; Jena, B.K.; Ramana Murthy, M.V., and Tushar K., 2020. Interference patterns observed in the Indian coastal ocean radar network. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 63-66. Coconut Creek (Florida), ISSN 0749-0208.

Indian Coastal Ocean Radar Network (ICORN) runs 10 shore- based High-Frequency Radar (HFR) systems for measuring 2D surface currents and waves, which cover four coastal states and the Andaman Islands. These coastal remote sensing systems are subjected to various interferences. This paper discusses the periodic interference patterns observed in the network and the possible causes for these patterns. The radial data file size from the HFR sites is used as a proxy to identify these patterns. Similarly, vertical Total Electron Content (TEC) is used to identify the influence of Ionosphere on HFR data. The Fast Fourier Transform (FFT) on these data sets showed a strong correlation between HFR and TEC data at diurnal and semi-diurnal frequencies as well as at 8, 6 and 4.8 hours periods. However; low pass filter HFR data does not show any seasonal or intra-seasonal pattern, except at the Andaman Islands, where it showed fortnightly and monthly patterns.

Ayyadurai, T.; Raguraman, G.; Ashokan, M., and Latha, G., 2020. Ambient noise measurement system for the Arctic region. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 67-70. Coconut Creek (Florida), ISSN 0749-0208.

Ambient noise measurements in the polar region are challenging due to the ice-covered environment and very low temperature prevailing in the region. The primary aim of this research work is to design and develop a system capable of associated components to withstand harsh environments, such as the Arctic region. This system consists of a hydrophone, a data acquisition system and a battery pack placed in an indigenously developed underwater pressure casing. While the water depth is 190 m, the noise measurement system is placed at a depth of 30 m. The objective of this work is to record the time series of ocean ambient noise in the Kongsfjorden fjord, Arctic region, covering the seasonal cycle and study the sea ice dynamics and biological noise.

Sanitha, S.K. and Madeswaran, P., 2020. Taxonomy matters in monitoring and EIA studies: An urgent need to revive systematic and taxonomy research in India. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 71-76. Coconut Creek (Florida), ISSN 0749-0208.

Human-induced loss of biodiversity is affecting the functions and services of the earth's ecosystems. Large regions of the biosphere are expected to be affected by the projected climate change, further aggravating the health of the ecosystems. It has been widely recognized that the successful management of any ecosystem cannot occur without an effective assessment of its regional biodiversity. However, monitoring or ecology studies exploring the relationship between biota and the environment have often overlooked the role of biodiversity. Since biodiversity is increasingly becoming an important component of ecosystem management, taxonomic accuracy is fundamental to prevent erroneous assessments and decisions in management and conservation policy. This paper therefore discusses how lack of taxonomy research is hindering marine monitoring and EIA studies in India. Here, we use the macrofaunal data from the Seawater Quality Monitoring (SWQM) program, the coastal monitoring program of India. We observed that the uncertainty in the biological data hampered a sound interpretation of the observed pattern, and is a major challenge to monitoring and EIA studies. Therefore, taxonomic uncertainty may lead to wrong conclusions and ultimately to inappropriate management plans.

Four major difficulties in effective biodiversity studies in India were identified. These are (1) lack of experts; (2) lack of appropriate support and funding for biodiversity studies; (3) the need to update regional literature for identification of most marine invertebrates and (4) lack of interaction among Indian researchers. Given the slow progress in taxonomy research, particularly marine invertebrates, there is an urgent need for networking among the Indian and international scientists, effective training, and an integrated approach. Reliable taxonomy offers an opportunity to provide relevant information to policy makers and environmental managers for skillfully manage the marine systems.

Anoop, T.R.; Sheela Nair, L.; Prasad, R.; Reji, S.; Ramachandran, K.K.; Prakash, T.N., and Balakrishnan Nair, T.M., 2020. Locally and remotely generated wind waves in the southwestern shelf sea of India. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 77-83. Coconut Creek (Florida), ISSN 0749-0208.

The Southwestern Shelf Sea (SWSS) of India has a distinct wave pattern, which makes it different as compared to the adjoining regions. Wave directional spectra during the monsoon season are comparatively broader and double peaked in contrast to that of the western shelf sea. The well-defined directional bi-modality is observed during the south west monsoon which is attributed to the coexistence of the south Indian Ocean swells and the southwest monsoon swells. The shamal swells generated by the shamal wind blowing from the Arabian Peninsula are found to have a significant influence on the wave pattern of the SWSS. In addition, the local sea breeze/land breeze also contributes significantly to the observed changes, particularly to the diurnal variation. A distinct phase lag in occurrence of the maximum significant wave height for the wind sea component is also observed in the northern region of the SWSS during the fair seasons.

Dhanya, S.; Mohan, R.; Mullai Vendhan, K.; Ramana Murthy, M.V., and Sajeev, R., 2020. Assessment of performance of a groin constructed on Puducherry coast - A case study. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 84-91. Coconut Creek (Florida), ISSN 0749-0208.

India, having coastline of about 7500 kms, is facing severe problems of erosion, threatening millions of lives. Construction of planned ports, harbours, and industries accelerate the erosion and degrade the environment along India's coastline. The reduced rainfall, due to changes in the monsoon pattern over the years, has in turn lessened the sediment inflow into the oceans. This reduction in the sediment flow leads to considerable erosion along the coastlines. Groins are typically built to stabilize a number of natural or manmade beaches against erosion, mainly due to a net loss of beach material. The influence of a groin is accretion of the beach material on the updrift side and erosion on the downdrift side. Puducherry, a Union Territory, is facing severe coastal erosion problems along some of the stretches, especially to the north of Puducherry harbour. In this study, the status and impact of a 60 m long groin constructed at Vaithikuppam, on Puducherry coastline is studied. A coupled and fully integrated 2D model for waves, currents and sediment transport is used for the assessment. The hydrodynamic processes and morphological stability near the groin are studied using field observations and bathymetric data. The numerical model results were validated and found to be in good agreement with the field data. The hydrodynamic conditions and sediment transport patterns are predicted using the model results and the impact of the groin on the morphological characteristics are established and presented.

Glejin, J.; Sanil Kumar, V., and Sheela Nair, L., 2020. Occurrence of gravity and infra gravity waves in the nearshore region at Ratnagiri, west coast of India. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 92-96. Coconut Creek (Florida), ISSN 0749-0208.

This study analyses the sea level data measured simultaneously using S4DW and directional Wave Rider Buoy (WRB) off Ratnagiri, eastern Arabian Sea, located along the west coast of the Indian sub-continent. The objective of the study is to investigate the presence of infra-gravity waves as well as the source of infra-gravity waves that reach the near-shore regions of eastern Arabian Sea. Based on FFT analysis of the wave data, the estimated mean infragravity wave height is 0.04 m with a peak value of 0.08 m whereas the mean wave period of the infra-gravity waves is 60 s with a standard deviation of 8.9 s. Detailed analysis of the WRB data (wave period in the range of 0-30 s) provide reliable evidence indicating the presence of infra-gravity waves in the eastern Arabian Sea. The source of infra-gravity waves that propagate into the nearshore region could be either remotely or locally generated waves. However, it is observed that the presence of long-period gravity waves in the region has a direct influence on the infra-gravity waves. The amplitude of the infra-gravity is found to increase with the arrival of long period swell waves and vice-versa.

Kerkar, J.P.; Seelam, J.K., and Jena, B.K., 2020. Wave height trends off central west coast of India. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 97-104. Coconut Creek (Florida), ISSN 0749-0208.

Wave height trends off three sites along 100 m and 20 m depth contours off the central west coast of India have been estimated using 46 years hindcast-wind-wave data simulated for the Indian Ocean region. The wind waves were simulated with NCEP/NCAR winds as input to a third generation spectral wind wave model. This study showed an increasing trend for the annual mean significant wave heights from south to north ranging between 0.25 and 0.36 cm/year. The wave heights during the southwest monsoon and fair weather periods were observed to have similar trends. The study also showed increasing trends in water depths of 20 m compared to that of 100 m water depth, wherein a maximum increase of 0.22 cm/year is observed.

Noujas, V. and Kankara, R.S., 2020. Shoreline evolution along Vengurla, south Maharashtra coast using a numerical model. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 105-110. Coconut Creek (Florida), ISSN 0749-0208.

Shoreline are very dynamic and undergo changes due to natural and various human interventions. Shoreline evolution models are very useful tools to understand the shoreline change behaviour over a period of time. In this study, a shoreline evolution model is implemented along Vengurla, west coast of India. Major inputs required for estimation of shoreline evolution are nearshore wave climate, bathymetry, sediment characteristics and initial coastline. Nearshore wave climate at a depth of 15 m were collected using wave rider buoy during the year 2015. Bathymetry, nearshore sediments and shoreline information were also collected during the same year. Initially shoreline evolution model was set up for one year and the results were verified with field data. Model results showed a good comparison with the measured data, except the extreme northern boundary of the study region. Further model run continued for 10 years with calibrated model. The result indicates approximately 20-30 m beach advancement in the southern boundary of the study region. Erosion of about 65 m was observed in the extreme northern boundary in the first year which reduced during the subsequent years and finally stopped after 5 years as the shoreline attained equilibrium. The result of this study can be used by coastal managers for suggesting suitable management plans along the sector.

Panda, U.S.; Pradhan, U.K.; Sujith Kumar, S.; Naik, S.; Begum, M.; Mishra, P., and Ramana Murthy, M.V., 2020. Bathing water quality forecast for Chennai coastal waters. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 111-117. Coconut Creek (Florida), ISSN 0749-0208.

Risks associated with the non-compliance of bathing water quality have been increasing and becoming a challenge to maintain and manage the coastal waters. Especially, along the coastal cities, the complex nature of sources and their variation due to diverse urban runoff, industrial discharges, port activities and fluxes from different sources are deteriorating the coastal water quality which directly affects the health of beach goers, tourist, coastal communities. The Environment (Protection) Rules, 1986 has classified the seawater, class-II criteria for bathing, contact water sports and commercial fishing for Indian coastal waters. Chennai, one of the largest coastal metropolitan cities with a population of 4.65 million, is a major industrial hub having unsafe coastal waters. It's water quality faces toxic and dangerous deterioration due to domestic and industrial wastes. This paper presents an integrated modelling and forecast system developed for Chennai coastal waters through data assimilation using in situ water quality data, deterministic hydrological, hydrodynamic and water quality models. The coupled hydrodynamic-water quality model with input from catchment hydrology solves transport and dispersion of pollutants along the flow pattern. Forcing parameters were downscaled from global models to input to the local domain. 5-day forecast of sea surface temperature (SST), salinity, dissolved oxygen (DO), biological oxygen demand (BOD) and coliform are generated with confidence from validation. This predictive model and forecasting is helpful to beach managers and policy makers for better management.

Ramesh, M.; Sheela Nair, L.; Ramachandran, K.K., and Prakash, T.N., 2020. Development of video monitoring system for coastal applications. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 118-125. Coconut Creek (Florida), ISSN 0749-0208.

A pilot study for continuous monitoring to understand the complex coastal processes has been launched by the Coastal Processes Group of NCESS by the installation of a video monitoring system at Valiathura beach of Thiruvananthapuram, SW coast of India. The integrated system which is being indigenously developed by NCESS is cost-effective and robust. It consists of three major components viz. hardware (cameras with continuous recording facility), software for processing of the recorded videos and the data communication part. The various components of pilot system have been successfully tested at the Valiathura site and parameters like the beach width, surf zone width and wave run-up are derived from the recorded video images. The video derived parameters are validated with field measurements, which have shown reasonably good correlation. Based on the test results, efforts are being made to further fine tune the system so that it can be used for societal applications like giving timely information and warning to the coastal community, particularly during a crisis or in dangerous situations. Further fine tuning of the hardware and software components of the integrated system for facilitating real-time coastal monitoring is underway. Once established, this facility will be extremely useful to the disaster management authorities for adopting appropriate disaster mitigation and management measures as continuous erosion is considered as a potential hazard.

Rupam, K.; Ferrer, V.A., and Ramachandran, K.K., 2020. Bathymetry estimation using multispectral imagery over an inland water body – Vembanad Lake, Kerala, India. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 126-131. Coconut Creek (Florida), ISSN 0749-0208.

The biological and biophysical characteristics of the nearshore and inland (estuarine) water bodies are mainly dependent on their bathymetry which also drives the coastal/estuarine hydrodynamics and other nearshore processes. The study of bathymetry in inland navigational backwaters of the coastal regions gain further importance due to the periodical dredging activities undertaken to maintain the required draft for navigation. The carrying capacity of the lakes gets affected due to sedimentation from the river inflow gradually altering the bathymetry. Conventional bathymetric soundings are highly time consuming and man power intensive which can be successfully augmented and made faster through remote sensing (RS) methods. The RS method can provide better spatial data compared to point-based measurements and also have the advantage of capturing temporal information. The present study explores the feasibility of retrieving bathymetry using satellite based remote sensing techniques for an inland coastal water body, aiming to provide synoptic inexpensive method for estimating and updating bathymetry data making it handy for coastal research and management. The study has been attempted in Vembanad Lake in Kerala, southwest coast of India. The ratio of the blue (450 - 515 nm) to the green (525 - 605 nm) wavelength of the Landsat satellite images as proposed by Stumpf was applied to generate the linear relationship between the reflectance and field measured depth information. The Kochi to Alappuzha National Waterway No. 3 bathymetry chart of the year 2005 is used as the in situ information for generating a site specific linear regression model which yielded a significant correlation coefficient of 0.753 (N = 707). The regression equation has been applied to generate the Satellite optical reflectance derived bathymetry map for the southern part of Vembanad Lake. The bathymetry obtained through this model has been validated with a set of independent depth sounding values (r² = 0.92; N = 66). By and large the Stumpf model has been found helpful in recreating water depth using multispectral images in clear waters that permit proper light penetration. However, the present study has shown the potential of its application even in the inland water bodies where the light penetration is affected by a high concentration of suspended sediments and floating vegetation (water hyacinth).

Mandal, S.; Pramanik, S.; Sil, S.; Arunraj, K.S., and Jena, B.K., 2020. Sub-mesoscale circulation features along the Andhra Pradesh coast, Bay of Bengal: Observations from HF radars. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 132-138. Coconut Creek (Florida), ISSN 0749-0208.

This work presents the coastal circulation variability along the Andhra coast in western Bay of Bengal (BoB) using hourly high frequency radar (HFR, 4.4 MHz) derived ocean surface currents during 2015. The comparison of daily averaged HFR surface currents with satellite derived currents shows high correlations (0.86, 0.70) and low errors (0.28 m s^-1, 0.25 m s^-1) for the zonal and meridional components. The HFRs captured and quantified the dominant circulation features associated with the reversal of boundary currents. The northward (southward) currents are observed from mid-March till May end (October to November with highest current speed of ∼1.58 (1.24) m s^-1 along the Andhra coast (between 15-17°N). In addition, the sub-mesoscale features associated with dominant circulation features are observed, like, the propagation of an anticyclonic eddy (81.80°E, 15.25°N) during March and cyclonic eddy (82.25°E, 15.40°N) during November. The mean vorticity pattern from the HFR currents shows the dipole nature during April - May to indicate the near coast upwelling signatures which are also supported by chlorophyll observations from satellite. The tidal driven currents, extracted from the HFRs, show that the semi-diurnal tidal constituent, M2 dominates during both the seasons with less intensity in March than in November. The distributions of the M2 tidal ellipses match well with the broad-scale current pattern in the offshore region. They follow the bathymetry in the nearshore region to indicate that it is driven by tides resulting in the generation of the shallow water tidal constituents (M3, M4, MS4 and M8) with significant amount of amplitudes.

Sujith Kumar, S.; Panda, U.S.; Pradhan, U.K; Mishra, P., and Ramana Murthy, M.V., 2020. Web-based decision support system for coastal water quality. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 139-144. Coconut Creek (Florida), ISSN 0749-0208.

Operational systems on real-time monitoring of coastal water quality can play a key role to counter and reduce the pollution causing hazardous events in the coastal region. An automated alert system is required to provide relevant information to the coastal authorities, water quality managers and other coastal stakeholders on a real-time basis to avoid any lead time or potential human errors. This paper presents an architecture for coastal water quality prediction and alert system by integrating different platforms and services to achieve scalability, provisioning of resources in real time, simplified deployment and management of resources and applications. The forecast system was developed through data assimilation from coupled hydrodynamic water quality models and field observations and archived in an integrated Database Management System (DBMS). A web-service is programmed to fetch the data from server on demand in order to disseminate the information to the public. Web applications use an architecture that breaks applications into discrete parts, using multiple programming languages and deploying the applications on several layers of technology. The other features of the website include Query builder as per user's specification, Fetch and display latest time series data on water quality parameters based on locations and graphical representation.

Dhanalakshmi, S. and Kankara, R.S., 2020. Assessment on shoreline retreat in response to sea level rise – Chennai coast. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 145-149. Coconut Creek (Florida), ISSN 0749-0208.

In the present condition, the rise in sea level due to climate change is a serious threat for the environment. Global average sea levels are predicted as 1.8 mm/y during 1870-2009 and nearly 2.8 mm/y along the Indian Coast by Intergovernmental Panel on Climate change (IPCC). Impacts of rise in sea-level will be the loss of land in coastal areas through erosion, submergence of the coastal landscape and the threat of inundation. Shore erosion causes the shoreline to retreat and this leads to affecting the erosion zone by moving the shoreline inland. In this study, the attempt is made to demarcate the impact of sea level rise along the Chennai coast (Tamil Nadu) located along the southeast coast of India. This area experiences threat from many disasters such as storm, cyclone, flood, tsunami and long-term sea level rise. The shoreline has been extracted and using DSAS tool in ArcGIS, long-term (1990-2012, 1990-2013, 1990-2014, 1990-2015 and 1990-2016) were analyzed using Linear regression Rate and Weighted Linear Regression. 36.7% of the coast was seen with eroding condition. Overall long-term analysis trend suggest that more than 60% of the region falls in stable to low accretion. Projection of climate change-induced SLR at different RCPs (2.6, 4.5, 6, 8.5) of IPCC AR5 on different time scale (2025, 2050, 2075, 2100) for the coasts of Chennai. The values range from 7.1 cm to 36.87 cm for RCP 2.6; 7.37 cm to 49.84 cm for RCP 4.5; 7.16 cm to 51.75 cm for RCP 6; 7.38 cm to 77.88 cm for RCP 8.5. Shoreline retreat to an increase in local sea level was mapped using the Bruun Rule. Since the Bruun Rule (BR) has some limitations, the modified Bruun rule was used to analyze the inundation factor. The area of horizontal inundation is estimated as ∼1.6 km (Bruun rule) and ∼1.1 km (Modified Bruun Rule). The required data was processed using GIS environment. Since we adhere to the fact that the coastal change is not a periodical accumulation per year, but that it entraps a value of future crisis assessment and gives a literal warning about the shore to be persevered.

Prasad, R.; Sheela Nair, L.; Kurian, N.P., and Prakash, T.N., 2020. Shoreline evolution along a placer mining beach of south-west coast of India. In: Sheela Nair, L.; Prakash, T.N.; Padmalal, D., and Kumar Seelam, J. (eds.), Oceanic and Coastal Processes of the Indian Seas. Journal of Coastal Research, Special Issue No. 89, pp. 150-157. Coconut Creek (Florida), ISSN 0749-0208.

The Chavara coast of 22 km length located along the south-west coast of India is well known for its rich heavy mineral deposits, also called as black sand deposits. Since 1930, the Indian Rare Earths Ltd. (IREL) and its predecessor companies have been engaged in beach sand mining along this coast for the extraction of heavy minerals. The mining of beach sand by the IREL and Kerala Minerals and Metals Ltd. (KMML) has been much beyond the sustainable limits for the past one and a half decades as indicated by different studies, and has caused drastic beach and innershelf morphological changes. In this study numerical modelling is carried out using the LITLINE module of LITPACK to simulate the shoreline evolution along this coast. The model outputs are calibrated and validated using the shorelines derived from satellite imageries and field measurements for the years 2000, 2006, 2010 and 2015. The calibrated and validated model has been used for further simulations for the period of 2000–2022 by inserting groins in tally with the field scenarios for different years. The influence of the short and long groins is predominant at the northern end, near to the Kayamkulam breakwater. If the present scenario persists, the deposition at the southern breakwater at Kayamkulam will be stabilized by the year of 2022. Orientation of the shoreline in the groin field area is found to be in accordance with the predominant northerly longshore transport. Due to the impact of intense mining, the recession in the shoreline and caving-in at the mining site will be even up to 300 m during the period of 2000–2022. The simulations show that the observed caving-in at the mining sites will aggravate further in the years to come if unsustainable mining is continued.