Shoreline Change Assessment and Forecasting Using GIS and Digital Shoreline Analysis System Along the Coast of Machilipatnam, Andhra Pradesh

Abstract

Coastlines or shorelines are sites of dynamic activities, and phenomenon such as wave and tidal actions, rate of sediment supply, sea level changes and morphological properties of the area play a critical role in shaping the coastal ecosystems. The present study analyzes the long-term shoreline change detection along the Machilipatnam coast in Andhra Pradesh using Geographic information system (GIS) and Digital shoreline analysis system (DSAS) for the past two decades (2000–2019); and then predicts the position of the shoreline in the upcoming 10 and 20 years. Multi-temporal LANDSAT images were used for shoreline extraction, and the erosion patterns and the shoreline change rates were estimated using four statistically accepted models, End Point Rate (EPR), Net Shoreline Movement (NSM), Linear Regression Rate (LRR) and Weighted Linear Regression (WLR). The results from NSM show 83.13% of negative distance along the study transects. The high percentage of negative distance indicates a very high rate of erosion along the study transects. The average EPR was estimated to be −13.52 with ±0.74 rate of uncertainty. The statistical significance of erosion was estimated as 82.27%. The average LRR was −13.55 ± 3.1. The high negative results of LRR again suggest an increased erosional environment along the shoreline. In our study, the values for LRR and WLR are same, both of which show landward movement of the shoreline (erosional). The analysis of NSR, EPR and LPR rates, thus, reveals a pronounced shoreline retreat in the Machilipatnam coastal zone during the study period. Beta forecasting was carried out to create Shoreline change envelope (SCE), and prediction maps of shoreline were produced for the next 10 and 20 years. The study has, thus, helped us manifest into a quantification of the trends and changes in the shoreline geometry and is a good precursor to efficient coastal classification and management.