GIS-based analysis of coastal vulnerability in southern province of Sri Lanka: insights from Matara district coastal area

Abstract

Coastal erosion is a substantial natural hazard that is affecting both the environment and human communities globally. Sri Lanka's coastline is about 1600 kilometres, with rich biodiversity and resources, and faces growing coastal erosion, notably in the southern coastal region especially in the Matara District. Therefore, understanding the causes and effects of coastal erosion is essential. This study aims to evaluate shoreline changes from 2000 to 2020 (Weligama to Dikwella) and involves three stages such as mapping shoreline changes using satellite data (Landsat) a digital shoreline analysis system (DSAS), statistical analysis for shoreline changes rates over 20 years, identifying interplay between factors. DSAS measures shoreline changes using baseline approaches and results are presented for both northeast monsoon (NEM) and southwest monsoon (SWM) seasons. NEM shows coastal accretion in Matara due to sediment transportation, while SWM reveals erosion in Devinuwara through strong waves and sediment movement. Sea level rise, rainfall, and river flow correlations influence erosion patterns. Overall, this study emphasizes the use of advanced technology to understand and monitor coastal erosion, help decision-making and develop effective strategies for protecting coastlines.