The eastern coast of India is one of the regions where most of the population resides in urban areas in the low-elevation coastal zone, making it vulnerable to frequent extreme weather events. The objectives of this study are to assess the short- to long-term shoreline changes of the Odisha coast, to understand how anthropogenic influences, and particularly extreme natural events, affect these changes, and to predict shoreline changes for 2050. This study utilized multi-temporal/spectral/spatial resolution satellite images and a digital shoreline analysis (DSAS) tool to appraise the short- (at five/six-year intervals) and long-term (1990-2019) shoreline dynamics along the coastal part of Odisha over the past three decades (1990-2019). The long-term shoreline analysis shows that the mean shoreline change is about 0.67 m/year and highlights that 52.47 % (227.4 km), 34.70 % (150.4 km), and 12.83 % (55.6 km) of the total Odisha coastline exhibit erosion, accretion, and stability, respectively. During the short-term analysis, the 2000-2005 period had the highest percentage of erosion (64.27 %), followed by the 2005-2010 period with an erosional trend of 59.06 %. The 1995-2000 period showed an accretion trend, whereas, during the last period, i.e., 2015-2019, the percentage of transects depicting erosion and accretion was almost similar. In 2050, 55.85 % of the transects are expected to show accretion, while 44.15 % would show erosion or a constant trend. The study identified the hotspots of coastal erosion along delineated study zones by synthesizing data from previous studies as well. The regional analysis of shoreline change along the Odisha coast would not only provide coastal managers with critical information on shoreline dynamics but also draw attention to vulnerable areas linked to shoreline dynamicity along the coast.
In this study, we have analyzed how geo-ecological cues for endangered Olive Ridley turtles' mass nesting behavior got modified by impact of four severe cyclones during 2010-2019 that made landfall in the vicinity of Rushikulya estuary, which is one of the largest mass nesting congregation (arribada) sites in the world. Analyzing last 10 years of shoreline dynamics, we show that even the slightest modification in beach morphology influenced their nesting behavior in Rushikulya rookery. Shoreline change analysis showed periodic phases of high/low erosion and the northward longshore sediment movement, which becomes impeded by the southern spit, the length of which increased by about 1800 m. During the analyzed period, the nesting behavior of Olive Ridley turtle was greatly influenced by changes in land use and land cover pattern around the Rushikulya rookery. Such reductions in tree cover and marshy land areas were majorly driven by anthropogenic activities and extreme weather events, such as cyclones. We also report increased mortality of turtles, no or false mass nesting events due to significant loss and/or erosion of the nesting sites due to cyclones. The results indicate that conservation of Olive Ridley turtles should be more holistic, or ecosystem centric, rather than species centric. It is important to maintain the ecological integrity of their habitat for highly synchronized mass nesting event and eventually their survival.