Shoreline Change Along Raigarh Coast, Maharashtra- a Bi-decadal Scenario

Abstract

The dynamic nature of the shoreline makes the coastal areas vulnerable to the impacts of climate change and sea level rise. Changes in any shoreline concerning erosion and deposition affect the coastal landforms and population. Delineating the shoreline and mapping the areas of erosion/deposition would undoubtedly augment the knowledge base in the coastal region and help the environmental planners better maintain the coastal tracts. Shoreline delineation is challenging; however, remote sensing data combined with the Geoinformatics technique helps extract and monitor shorelines. The present paper attempts to delineate and analyze the shoreline changes over the bi-decade time frame for the coastal tracts of Raigarh. Satellite data (Landsat) and tide level data were employed in this work. Short-time shoreline change has been analyzed for five-time sections starting from 2000, 2004, 2008, 2012, 2016, and 2019, and long-term shoreline change encompasses the 2000 to 2019 scenario. The methodology adopted for this study involved image processing techniques for delineating the shoreline. The automated Shorelines were extracted using the Digital Shoreline Analysis System (DSAS) for the images prepared by employing a few indices using the ISODATA unsupervised classification technique. The present analysis results portray the Raigarh coast's dynamic nature. A cyclic pattern of erosion and deposition has been observed in the short-time analysis. Over twenty years, the Raigarh shoreline exhibits an overall erosion of -0.12 m/yr. A detailed analysis had done on the small section depicting mangrove patches, and this is to understand the response of mangroves at the zone of erosion and deposition. Mangrove patches with anthropogenic stress represent a zone of erosion, and patches with mature growth, protected from human interference, represent a zone of deposition. The mangrove patches, specifically over the northernmost parts like Kamothe, Khandeshwar, and Vaghivali, which are close to urban agglomeration or other allied anthropogenic activities like industry, exhibit an active erosion process. Mangrove patches with mature trees have well-developed root systems representing the deposition zone. Navedarbeli well represents such cases. Patches like Kalinje reported deposition, which is the result of a successful conservation program by the mangrove cell of Maharashtra. Overall, the headland regions of Alibag, Murud, and Srivardhan talukas are more susceptible to erosion. This type of study will help in monitoring the shoreline as well as will help in restoring and preserving the mangrove habitat.