Department Of Geography

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Author: search.filters.author.Kar, Dipika

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    Response of long- to short-term tidal inlet morphodynamics on the ecological ramification of Chilika lake, the tropical Ramsar wetland in India
    (Elsevier B.V., 2021-10-06T00:00:00) Mishra, Manoranjan; Acharyya, Tamoghna; Chand, Pritam; Santos, Celso Augusto Guimar�es; Silva, Richarde Marques da; Santos, Carlos Antonio Costa dos; Pradhan, Subhasis; Kar, Dipika
    The long- to short-term morphodynamic response in low-lying coastal wetlands raises serious concerns worldwide about the loss of their biodiversity and ecological ramifications due to change in tidal amplitude and cyclonic events. One such place worth studying is Chilika lake, India, a prominent Ramsar site, the largest brackish water lagoon in Asia, and the second-largest coastal lagoon in the world. It experiences frequent cyclone landfalls and strong littoral drift that tends to open/close the tidal inlet. The goal of this study was to analyze the response of slow onset events such as long- (1952�2020) to short-term (~annual scale from 1989 to 2020) tidal inlet movement, shoreline change (1990�2020 with almost every five-year interval), spit morphodynamics (~annual scale from 1989 to 2020) on ecological ramification in Chilika lake as well as the implications of sudden onset event such as cyclonic landfall. In this study, we used the Digital Shoreline Change Analysis System (DSAS) to compute the statistics of shoreline change rate by calculating end point rate (EPR) values for short-term shoreline change (1990, 1995, 2000, 2005, 2011, 2016, and 2020) and weighted linear regression (WLR) for long-term shoreline change (1990�2020). The results show that Chilika lake experienced both erosion and accretion processes with a remarkably high erosion rate of 19.87 m year?1 and accretion of 16.91 m year?1 during a long-term scale (1990�2020). The average erosion and accretion rates were 2.25 m year?1 and 4.67 m year?1, respectively, during the past three decades (1990�2020). The short-term analysis suggests that the highest mean erosion of 4.37 m year?1 occurred during 2005�2011, mainly due to cyclonic storms, reduction in sediment discharge, and lunar eclipse, which induced tide with very high amplitude in August 2008. Overall, the annual scale analysis of tidal inlet shows a shifting trend towards the northward side even after the artificial opening of an inlet in 2000. It can be ascribed mainly to the prevalent direction of longshore drift along this coast. This study observed that the landfall of cyclones significantly affects the spit morphodynamics and opening of the tidal inlet, which defines the inflow of the seawater into the lagoon and further substantial impacts on the ecological ramification. The current study's methodology can be extended to comprehend the response of long- to short-term changes of the tidal inlet, shoreline, and spit morphodynamics on the ecological ramification of coastal lagoons worldwide along with impacts of sudden-onset events caused by cyclonic landfall. � 2021 Elsevier B.V.
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    Analyzing shoreline dynamicity and the associated socioecological risk along the Southern Odisha Coast of India using remote sensing-based and statistical approaches
    (Taylor and Francis Ltd., 2021-02-06T00:00:00) Mishra, Manoranjan; Acharyya, Tamoghna; Chand, Pritam; Santos, Celso Augusto Guimar�es; Kar, Dipika; Das, Prabhu Prasad; Pattnaik, Namita; Silva, Richarde Marques da; Nascimento, Thiago Victor Medeiros do
    The coastal zone is an extremely volatile environment and is constantly changing. We assessed short- and long-term shoreline changes in the Ganjam district of Odisha on the eastern coast of India from 1990 to 2019 using Landsat satellite imagery and the Digital Shoreline Analysis System (DSAS) tool in a geographic information system. In addition, we have also projected the likely future coastline position for the 2030�2040 period and the possible impact on the socioecology of the shoreline. In this study, we used the endpoint rate (EPR) analysis, weighted linear regression (WLR) analysis, and trigonometric functions to analyze the shoreline from 1990 to 2019 and also forecasted for year 2030 and 2040. The shoreline of the Ganjam coastal zone is one of the most biologically productive ecosystems in the world, and it is well-known due to the breeding and mass nesting grounds of olive ridley turtles and the economically connected ports, famous beaches, and cyclone-prone areas. During the study period (1990�2019), the average erosion and accretion rates in the Ganjam shoreline were ?2.58 m/year and 11.63 m/year, respectively. The rate of shoreline erosion increased during years of cyclone landfall, which was revealed during the short-term shoreline analysis of the periods from 1995 to 2000 (1999 super cyclone) and 2015 to 2019 (2019 category�IV cyclone Fani). The short- to long-term analyses of the shoreline assisted in identifying erosion (Ramyapatna, Podampetta) and accretion (southern part of Gopalpur port, spits along the Bahuda and Rushikulya Rivers) hotspots within the Ganjam coastal zone. The identified erosion hotspots could submerge a significant number of coastal villages that serve as breeding and mass nesting grounds for olive ridley turtles. The dominant erosion along the Ganjam coastline are likely to enhance socioecological risk and further threaten coastal communities in the future. The output of the undertaken research will benefit coastal planners, policymakers, and conservationists by helping them to formulate the most suitable action plan for coastal zone management with consideration of all stakeholders. � 2021 Informa UK Limited, trading as Taylor & Francis Group.