Pallikaranai, India
Pallikaranai, India

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Mishra P.,ICMAM Project Directorate | Patra S.K.,National Institute of Ocean Technology | Murthy M.V.R.,National Institute of Ocean Technology | Mohanty P.K.,Berhampur University | Panda U.S.,ICMAM Project Directorate
Natural Hazards | Year: 2011

A 97-day-long record on waves and currents was obtained using wave rider buoy and current meter moored at 2.5 km off Gopalpur from 19 May to 23 August 2008 representing southwest monsoon months. A Valeport tide gauge was used to record water level at Gopalpur port. Simultaneously, beach profiles at 4 transects were monitored using real-time kinematic (RTK) global positioning system (GPS). A total of 636,167 waves were analyzed for the period; a range of 3,200-9,700 waves approach the coast in an individual day. During the study, unusual characteristics of wave were observed on July 29, 2008, with a magnitude of significant wave height, Hs = 2.85 m, maximum wave height, Hmax = 5.22 m, and peak wave period, Tp = 10.2 s, and on August 11, 2008, with Hs = 2.28 m, Hmax = 5.37 m, and Tp = 11.1 s. Significant beach loss was noticed during these periods, and severe erosion was recorded on August 1, 2008. Beach profile data indicates that 18-58 cu. m/m sediment was lost during the study period. The paper provides an overview of the statistical analysis of wave heights, periods, direction, and spectral energy density and explains the cause of coastal erosion and loss of sediment. © 2011 Springer Science+Business Media B.V.


Shaik A.R.,National Institute of Oceanography of India | Biswas H.,National Institute of Oceanography of India | Reddy N.P.C.,National Institute of Oceanography of India | Srinivasa Rao V.,National Institute of Oceanography of India | And 2 more authors.
Environmental Impact Assessment Review | Year: 2015

In recent decades, material fluxes to coastal waters from various land based anthropogenic activities have significantly been enhanced around the globe which can considerably impact the coastal water quality and ecosystem health. Hence, there is a critical need to understand the links between anthropogenic activities in watersheds and its health. Kakinada Bay is situated at the SW part of the Bay of Bengal, near to the second largest mangrove cover in India with several fertilizer industries along its bank and could be highly vulnerable to different types of pollutants. However, virtually, no data is available so far reporting its physicochemical status and microalgal diversity at this bay. In order to fill this gap, we conducted three time series observations at a fixed station during January, December and June 2012, at this bay measuring more than 15 physical, chemical and biological parameters in every 3. h over a period of 36. h in both surface (0. m) and subsurface (4.5. m) waters. Our results clearly depict a strong seasonality between three sampling months; however, any abnormal values of nutrients, biological oxygen demand or dissolved oxygen level was not observed. A Skeletonema costatum bloom was observed in December which was probably influenced by low saline, high turbid and high Si input through the river discharge. Otherwise, smaller diatoms like Thalassiosira decipiens, Thalassiothrix frauenfeldii, and Thalassionema nitzschioides dominated the bay. It is likely that the material loading can be high at the point sources due to intense anthropogenic activities, however, gets diluted with biological, chemical and physical processes in the offshore waters. © 2015 Elsevier Inc.


Ganguly D.,ICMAM Project Directorate | Robin R.S.,ICMAM Project Directorate | Vardhan K.V.,ICMAM Project Directorate | Muduli P.R.,ICMAM Project Directorate | And 3 more authors.
Journal of Experimental Marine Biology and Ecology | Year: 2013

The responses of two tropical phytoplankton species (one diatom and one cyanobacterium) at various nutrient concentrations were studied to determine their optimum growth conditions. Optimum salinities for these two species were also determined prior to the nutrient limitation study. As a part of ecosystem monitoring at Asia's largest brackish water lagoon (Chilika), axenic cultures of Chaetoceros simplex and Anabaena sp. were maintained and nutrient concentrations were regulated according to the in situ conditions. At given pre-defined environmental conditions (light, nutrient, temperature, salinity etc.) the maximum growth rate of 0.043h?1 and 0.040h?1 was recorded for C. simplex and Anabaena sp. at N/P ratios of 12 and 8, respectively. Addition of ammonia significantly stimulated the growth of Anabaena sp., whereas C. simplex did not show such significant increase. Anabaena sp. showed larger positive response towards the enrichment of phosphate-phosphorous (PO4-P) in terms of specific growth rate compared to that of C. simplex. For both the species, relative decrease in available dissolved inorganic nitrogen (DIN) was indicated by an apparent decrease in chlorophyll-b/a ratios. In in vitro conditions chlorophyll to carbon ratio increases with increasing N concentration, and was found to be higher for C. simplex relative to Anabaena sp. The results suggested that Anabaena sp. is the better competitor at low nutrient availability and has higher adaptation ability than C. simplex. © 2013 Elsevier B.V.


Praveen S.S.,Center for Earth Science Studies | Reshmi A.K.,Center for Earth Science Studies | Dhanya P.,Center for Earth Science Studies | Kalarani S.A.,Center for Earth Science Studies | And 4 more authors.
Marine Geodesy | Year: 2011

The Tsunami N2 model has been used to simulate the Tsunami amplitudes and horizontal extent of inundation from the Indian Ocean Tsunami of December 26, 2004. The areas considered here pertain to the southwest coast of India, comprising the states of Kerala and Karnataka. In addition, the simulation of tsunami amplitudes and inundation has also been done for some selected islands of the Lakshadweep group of islands of India. © Taylor & Francis Group, LLC.


Nayak S.,Earth System Science Organisation | Usha T.,ICMAM Project Directorate | Kankara R.S.,ICMAM Project Directorate | Reddy N.T.,ICMAM Project Directorate
Marine Geodesy | Year: 2012

Coastal topography is the principal variable that affects the movement of the tsunami wave on land. Therefore, land surface elevation data are critical to a tsunami model for computing extent of inundation. Elevation data from India's remote sensing satellite CARTOSAT-1 are available for the entire Indian coastline, while elevation data collected using Airborne Laser Terrain Mapper (ALTM) are only available for selected sections of the coastline. This study was carried out to evaluate the suitability of CARTOSAT-1 and ALTM elevation data sets in the tsunami inundation modeling. Two areas of the coastal Tamil Nadu that were severely affected during the December 2004 tsunami and surveyed extensively for mapping the extent of inundation were selected as the study areas. Elevation data sets from ALTM, CARTOSAT-1 and field measurement collected using Real-time Kinematic GPS (RTK-GPS) were compared for these areas. The accuracy of ALTM and CARTOSAT-1 data, the significance of interpolation methods and data used on model outputs were studied. The analysis clearly revealed that the elevation accuracy of CARTOSAT-1 data (+/-2m) was much lower than ALTM data (+/-0.6m). However, it was found that despite the differing elevation accuracy, both ALTM and CARTOSAT-1 can be used to produce tsunami inundation maps for open coasts with an accuracy of 185 m (2 grid cells) at 75% and 50% confidence level, respectively. © 2012 Copyright Taylor and Francis Group, LLC.


Murthy M.V.R.,ICMAM Project Directorate | Reddy N.T.,ICMAM Project Directorate | Pari Y.,ICMAM Project Directorate | Usha T.,ICMAM Project Directorate | Mishra P.,ICMAM Project Directorate
Natural Hazards | Year: 2012

Nagapattinam, in the east coast of India, was severely affected during the deadliest Indian Ocean tsunami of December 26, 2004. The tsunami caused heavy damage to life and property, and the death toll was about 3,378 in Nagapattinam taluk. Certain villages along the coast witnessed large inundation while adjacent villages were protected from the fury of the tsunami waves. This study was carried out to examine the underlying causes for the vulnerability along Nagapattinam coast with the help of field observations, remote sensing, and geographical information system as tools. Coastal areas with high sand dunes have been protected from tsunami, and areas adjacent to backwaters were inundated. Realtime Kinematic Global Positioning System and high-resolution satellite data were used to map the topographic information and maximum extent of inundation. Thematic maps on land use, land cover, and coastal geomorphology were generated using remote sensing and field data. Using field data as the primary source of information, tsunami hazard maps have been generated for Nagapattinam. © 2011 Springer Science+Business Media B.V.


Rao A.D.,Indian Institute of Technology Delhi | Murty P.L.N.,Indian Institute of Technology Delhi | Jain I.,Indian Institute of Technology Delhi | Kankara R.S.,ICMAM Project Directorate | And 2 more authors.
Natural Hazards | Year: 2013

The devastation due to storm surge flooding caused by extreme wind waves generated by the cyclones is a severe apprehension along the coastal regions of India. In order to coexist with nature's destructive forces in any vulnerable coastal areas, numerical ocean models are considered today as an essential tool to predict the sea level rise and associated inland extent of flooding that could be generated by a cyclonic storm crossing any coastal stretch. For this purpose, the advanced 2D depth-integrated (ADCIRC-2DDI) circulation model based on finite-element formulation is configured for the simulation of surges and water levels along the east coast of India. The model is integrated using wind stress forcing, representative of 1989, 1996, and 2000 cyclones, which crossed different parts of the east coast of India. Using the long-term inventory of cyclone database, synthesized tracks are deduced for vulnerable coastal districts of Tamil Nadu. Return periods are also computed for the intensity and frequency of cyclones for each coastal district. Considering the importance of Kalpakkam region, extreme water levels are computed based on a 50-year return period data, for the generation of storm surges, induced water levels, and extent of inland inundation. Based on experimental evidence, it is advocated that this region could be inundated/affected by a storm with a threshold pressure drop of 66 hpa. Also it is noticed that the horizontal extent of inland inundation ranges between 1 and 1. 5 km associated with the peak surge. Another severe cyclonic storm in Tamil Nadu (November 2000 cyclone), which made landfall approximately 20 km south of Cuddalore, has been chosen to simulate surges and water levels. Two severe cyclonic storms that hit Andhra coast during 1989 and 1996, which made landfall near Kavali and Kakinada, respectively, are also considered and computed run-up heights and associated water levels. The simulations exhibit a good agreement with available observations from the different sources on storm surges and associated inundation caused by these respective storms. It is believed that this study would help the coastal authorities to develop a short- and long-term disaster management, mitigation plan, and emergency response in the event of storm surge flooding. © 2012 Springer Science+Business Media B.V.


Mishra P.,ICMAM Project Directorate | Usha T.,ICMAM Project Directorate | Ramanamurthy M.V.,ICMAM Project Directorate
Continental Shelf Research | Year: 2014

The Sumatra tsunami of 26 December 2004 with a moment magnitude of 9.3 Mw caused colossal damage to the south-southeastern Indian coast and Andaman-Nicobar group of Islands. However, the northeastern coastline bordering the northwestern Bay of Bengal remained unaffected although a tidal station located in the region recorded the highest water level (~2.5. m) for the entire east coast of India on the eventful day. As a part of hazard mitigation and planning for the northeastern coast, four major settlements, viz., Gopalpur, Puri, Paradip and Digha were evaluated for tsunami vulnerability. Inundation and run-up scenarios were generated for Bay of Bengal earthquake sources such as Arakan-1762, Car Nicobar-1881, North Andaman-1941 and Sumatra 2004 using TUNAMI N2 model. The paper describes computed run-up heights and landward inundation for 20-25. km coastal stretch with different geomorphologies and topographical characteristics. Simulation results indicate that the model is able to generate a comparable run-up of 2-4.5. m for 2004 Sumatra event for Paradip region while at other locations of the coastline, it was largely unnoticed as the inundation remained within the beach limit; however water entered inland mainly through the waterways and inundated low-lying areas. It is concluded that northeast coast of India is relatively safe from the tsunami originating in Bay of Bengal region. © 2014 Elsevier Ltd.


Muduli P.R.,ICMAM Project Directorate | Kanuri V.V.,ICMAM Project Directorate | Robin R.S.,ICMAM Project Directorate | Charan Kumar B.,Andhra University | And 4 more authors.
Estuarine, Coastal and Shelf Science | Year: 2012

Biogeochemical Carbon cycling was studied in Asia's largest brackish lagoon, Chilika on the east coast of India. Systematic time-series observations were made at 35 hydrologically different stations over the entire lagoon. The first of these kinds of measurements reveal, inter and intra annual variability of partial pressure of CO 2 (pCO 2). A comparative analysis of pCO 2, CO 2 flux over four years (2005, 2009, 2010 and 2011) showed that the northern part of the lagoon maintained the highest levels of pCO 2, with maximum CO 2 efflux to the atmosphere associated with peak monsoon period. The high pCO 2 corresponded to a significant decrease in pH (∼0.8) from the low to high flow periods. Higher bacterial abundance (1.55 ± 0.28 × 10 9 cells L -1) and bacterial respiration (185.31 ± 105.37 μg C L -1 d -1), suggested high levels of organic carbon decomposition during the high flow period. In contrast, the southern sector was least affected by river discharge, with low pCO 2 values and CO 2 flux as in the dry period. The central part and outer channel of the lagoon had intermediate characteristics. During high flow, the air-water CO 2 flux from the entire lagoon was estimated to be 31.2 mol C m -2 y -1, which was comparatively very high with respect to the mean CO 2 emission from the entire subtropical and tropical estuaries. Highest CO 2 flux (65.98 mol C m -2 y -1) was observed in the northern sector, followed by the outer channel (17.61 mol C m -2 y -1), central sector (15.69 mol C m -2 y -1) and southern sector (14.44 mol C m -2 y -1). The northern part of Chilika lagoon being an important river-influenced region was responsible for the biological transformation of organic carbon to inorganic carbon and emitting CO 2 to the atmosphere. Such a sectoral approach would reveal zonal influences of CO 2 within a water body along with conditions leading to sink or a source. © 2012 Elsevier Ltd.


Kankara R.S.,ICMAM Project Directorate | Mohan R.,Annamalai University | Venkatachalapathy R.,Annamalai University
Journal of Coastal Research | Year: 2013

A thorough knowledge of hydrodynamic conditions of coastal waters is a primary requirement for understanding and resolving environmental management issues. The present study is aimed at characterizing the hydrodynamic regime of Chennai coastal waters through field investigations and numerical modelling. To this end, time series oceanographic data on tide, current, and wind were collected for 15 days each during SW monsoon and NE monsoon seasons. The data analysis revealed that tides were semidiurnal in nature and that the ratio of diurnal (O1, K1) and semidiurnal (M2, S 2) constituents was 0.19 and 0.24 for the two respective seasons. The average current was 17 cm/s N during SW monsoon and 10 cm/s S during NE monsoon. A two-dimensional hydrodynamic model was also set up and validated with the field data successfully. The model results of water level and current were compared with field observations for both seasons and found to be satisfactory. The correlation was 0.89 and 0.99 for surface elevation and 0.56 and 0.73 for current speed. The relative mean absolute error (RMAE) and index of agreement (IoAd) were also computed for both seasons. The RMAE and IoAd analysis revealed that model validation was found to be "excellent" for water level and "very good" for current. © 2013 the Coastal Education & Research Foundation (CERF).

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