Department Of Geography

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Author: search.filters.author.Meraj, GowharSubject: search.filters.subject.DSAS

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    Assessing the Impact of the 2004 Indian Ocean Tsunami on South Andaman�s Coastal Shoreline: A Geospatial Analysis of Erosion and Accretion Patterns
    (MDPI, 2023-05-28T00:00:00) Singh, Saurabh; Singh, Suraj Kumar; Prajapat, Deepak Kumar; Pandey, Vikas; Kanga, Shruti; Kumar, Pankaj; Meraj, Gowhar
    The 2004 Indian Ocean earthquake and tsunami significantly impacted the coastal shoreline of the Andaman and Nicobar Islands, causing widespread destruction of infrastructure and ecological damage. This study aims to analyze the short- and long-term shoreline changes in South Andaman, focusing on 2004�2005 (pre- and post-tsunami) and 1990�2023 (to assess periodic changes). Using remote sensing techniques and geospatial tools such as the Digital Shoreline Analysis System (DSAS), shoreline change rates were calculated in four zones, revealing the extent of the tsunami�s impact. During the pre- and post-tsunami periods, the maximum coastal erosion rate was ?410.55 m/year, while the maximum accretion was 359.07 m/year in zone A, the island�s east side. For the 1990�2023 period, the most significant coastal shoreline erosion rate was also recorded in zone A, which was recorded at ?2.3 m/year. After analyzing the result, it can be seen that the tsunami severely affected the island�s east side. To validate the coastal shoreline measurements, the root mean square error (RMSE) of Landsat-7 and Google Earth was 18.53 m, enabling comparisons of the accuracy of different models on the same dataset. The results demonstrate the extensive impact of the 2004 Indian Ocean Tsunami on South Andaman�s coastal shoreline and the value of analyzing shoreline changes to understand the short- and long-term consequences of such events on coastal ecosystems. This information can inform conservation efforts, management strategies, and disaster response plans to mitigate future damage and allocate resources more efficiently. By better understanding the impact of tsunamis on coastal shorelines, emergency responders, government agencies, and conservationists can develop more effective strategies to protect these fragile ecosystems and the communities that rely on them. � 2023 by the authors.
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    Decoding Chambal River Shoreline Transformations: A Comprehensive Analysis Using Remote Sensing, GIS, and DSAS
    (MDPI, 2023-05-08T00:00:00) Singh, Saurabh; Meraj, Gowhar; Kumar, Pankaj; Singh, Suraj Kumar; Kanga, Shruti; Johnson, Brian Alan; Prajapat, Deepak Kumar; Debnath, Jatan; Sahariah, Dhrubajyoti
    Illegal sand mining has been identified as a significant cause of harm to riverbanks, as it leads to excessive removal of sand from rivers and negatively impacts river shorelines. This investigation aimed to identify instances of shoreline erosion and accretion at illegal sand mining sites along the Chambal River. These sites were selected based on a report submitted by the Director of the National Chambal Sanctuary (NCS) to the National Green Tribunal (NGT) of India. The digital shoreline analysis system (DSAS v5.1) was used during the elapsed period from 1990 to 2020. Three statistical parameters used in DSAS�the shoreline change envelope (SCE), endpoint rate (EPR), and net shoreline movement (NSM)�quantify the rates of shoreline changes in the form of erosion and accretion patterns. To carry out this study, Landsat imagery data (T.M., ETM+, and OLI) and Sentinel-2A/MSI from 1990 to 2020 were used to analyze river shoreline erosion and accretion. The normalized difference water index (NDWI) and modified normalized difference water index (MNDWI) were used to detect riverbanks in satellite images. The investigation results indicated that erosion was observed at all illegal mining sites, with the highest erosion rate of 1.26 m/year at the Sewarpali site. On the other hand, the highest accretion was identified at the Chandilpura site, with a rate of 0.63 m/year. We observed significant changes in river shorelines at illegal mining and unmined sites. Erosion and accretion at unmined sites are recorded at ?0.18 m/year and 0.19 m/year, respectively, which are minor compared to mining sites. This study�s findings on the effects of illegal sand mining on river shorelines will be helpful in the sustainable management and conservation of river ecosystems. These results can also help to develop and implement river sand mining policies that protect river ecosystems from the long-term effects of illegal sand mining. � 2023 by the authors.
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    Assessing the impacts of current and future changes of the planforms of river Brahmaputra on its land use-land cover
    (Elsevier B.V., 2023-02-02T00:00:00) Debnath, Jatan; Sahariah, Dhrubajyoti; Lahon, Durlov; Nath, Nityaranjan; Chand, Kesar; Meraj, Gowhar; Kumar, Pankaj; Kumar Singh, Suraj; Kanga, Shruti; Farooq, Majid
    River bankline migration is a frequent phenomenon in the river of the floodplain region. Nowadays, channel dynamics-related changes in land use and land cover (LULC) are becoming a risk to the life and property of people living in the vicinity of rivers. A comprehensive evaluation of the causes and consequences of such changes is essential for better policy and decision-making for disaster risk reduction and management. The present study assesses the changes in the Brahmaputra River planform using the GIS-based Digital Shoreline Analysis System (DSAS) and relates it with the changing LULC of the floodplain evaluated using the CA-Markov model. In this study, the future channel of the Brahmaputra River and its flood plain's future LULC were forecasted to pinpoint the erosion-vulnerable zone. Forty-eight years (1973�2021) of remotely sensed data were applied to estimate the rate of bankline migration. It was observed that the river's erosion-accretion rate was higher in early times than in more recent ones. The left and right banks� average shifting rates between 1973 and 1988 were ?55.44 m/y and ?56.79 m/y, respectively, while they were ?17.25 m/y and ?48.49 m/y from 2011 to 2021. The left bank of the river Brahmaputra had more erosion than the right, which indicates that the river is shifting in the leftward direction (Southward). In this river course, zone A (Lower course) and zone B (Middle course) were more adversely affected than zone C (Upper course). According to the predicted result, the left bank is more susceptible to bank erosion than the right bank (where the average rate of erosion and deposition was ?72.23 m/y and 79.50 m/y, respectively). The left bank's average rate of erosion was ?111.22 m/y. The research assesses the LULC study in conjunction with river channel dynamics in vulnerable areas where nearby infrastructure and settlements were at risk due to channel migration. The degree of accuracy was verified using the actual bankline and predicted bankline, as well as the actual LULC map and anticipated LULC map. In more than 90% of cases, the bankline's position and shape generally remain the same as the actual bankline. The overall, and kappa accuracy of all the LULC maps was more than 85%, which was suitable for the forecast. Moreover, chi-square (x2) result values for classified classes denoted the accuracy and acceptability of the CA-Markov model for predicting the LULC map. The results of this work aim to understand better the efficient hazard management strategy for the Brahmaputra River for hazard managers of the region using an automated prediction approach. � 2023 China University of Geosciences (Beijing) and Peking University