The trend of shoreline variability in the southwest coast of Vietnam using remote sensing data and the digital shoreline analysis system (DSAS)

Tran Anh Tuan1,*, Vu Le Phuong1 , Tran Thi Tam2 , Pham Viet Hong1 , Le Dinh Nam1 , Nguyen Thi Anh Nguyet1

Received: 3 September 2020; Accepted: 26 November 2020

Abstract

This paper presents the results of shoreline trend detection in Vietnam’s southwest coast in the period 2000– 2018. Landsat satellite image data used includes TM sensor for the years of 1999, 2000, 2005, 2006, 2009, 2010, and the OLI sensor for the years of 2015, 2016 and 2018. Firstly, the Automated Water Extraction Index (AWEI) method was applied to produce water index images from spectral bands of Landsat data. Secondly, shoreline generations were extracted based on the analysis and determination of the threshold value of the land and water boundary on AWEI images. Then, the Digital Shoreline Analysis System (DSAS) was implemented to estimate the variability rate (m/year) using the Linear Regression Rate (LRR) method at all of the measurement points where the DSAS transects (100 m apart) crossed shoreline generations. Positive (+) or negative (-) LRR values indicate the shoreline trends were advanced or retreated, respectively. Lastly, a five-level hierarchical system which includes very weak (< 2.5 m/year), weak (2.5– 5 m/year), medium (5–10 m/year), strong (10–30 m/year) and very strong (> 30 m/year) was used to divide the study area into eight zones with various shoreline trends.

Keywords: Trend, shoreline change, remote sensing, DSAS, southwest coast of Vietnam