Journal of Geography  & Natural Disasters
Open Access

Abstract

Analysis of Coastal Erosion using Linear Regression Rate and End Point Rate Approaches Case Study:Southern Coastal Line, Sri Lanka Weligama Bay

Pussella Gamaathi Ralalage Naleen Indika Pussella* and RKD Gunarathna

The coastal zone is defined as the area bounded by the band of ocean and the adjacent strip of land. This zone, in Sri Lanka, extends up to 300 m inland along the 1760 km coast. Various developmental projects have been installed in the coastal area of Sri Lanka, placing a considerable pressure on it, leading to various coastal hazards such as coastal erosion, seawater intrusion, coral bleaching, and temporal and long term shoreline changes. With the main objective of assessing the displacement of the coastline on the landward side by the forces of waves and currents which is known as the coastal erosion, this study was conducted for a part of Southern coastal line of Sri Lanka.

In order to calculate the Linear Regression Rate (LRR) and End Point Rate (EPR) of the erosion and to identify the key erosion hotspots of the study area, Digital Shoreline Analysis System (DSAS) tools were used in the GIS application. Temporal shore lines for different time periods were generated from the process of digitizing of Google Earth images which were taken in the years of 2006, 2010, 2014, 2017, 2018, 2019, 2020 and 2021. Further, 1:5,000 map prepared by the Survey Department of Sri Lanka and Landsat images extracted from USGS website were taken as the base map for the study. The erosion or the accretion regimes for 50 m orthogonal transects along the coastline were calculated based on the baseline and shorelines data. Finally, the coast line was classified as high erosion, moderately erosion, low erosion, stable, low accretion, moderately accretion and high accretion, using the resulting rates.

According to the results of the study, it can be identified that Weligama Bay shoreline exhibits a significant variation in the EPR value over the course of the relevant study period. Based on EPR, Weligama bay shows the maximum accretion rate as 2.3 m/year and the maximum erosion rate as -1.93 m/year. The results show that the area of the study is experiencing anthropogenic-caused coastal erosion due to the significant changes in the environment and shoreline. Human activities rather than natural events like climate change, sea level rise, and natural disaster conditions are the main cause of coastal erosion in the area under study.

Published Date: 2022-11-28; Received Date: 2022-10-24