Spatial and Temporal Evolution Characteristics of the Salween River Delta from 1973 to 2021

Abstract

We obtained sixteen clear-sky remote sensing images of Landsat series data from 1973 to 2021 and extracted continental and island coastlines of the Salween River Delta based on the Modified Normalized Difference Water Index (MNDWI) and visual interpretation correction. We determined the overall evolution of coastlines with statistical and superposition analysis and applied the Digital Shoreline Analysis System (DSAS) to summarize the spatial and temporal evolution process and characteristics in the past 50 years. Experimental results show that (1) the overall change of the coastline was more rapid on the island than on the continent, and on the Indian Ocean side than on the continental side, (2) the total area of the island increased by 91.16 km2 from 1973 to 2021, the area of Bilu Island increased by 50.38 km2, the length of the continental coastline decreased by 0.39 km, and the length of the coastline of the Bilu Island increased by 6.43 km, (3) the Linear Regression Rate (LRR) were: 4.69 m/yr for the total coastline, 1.06 and −2.07 m/yr, respectively, for the western and southern branches of the continental coastline, and 0.83 and 21.52 m/yr, respectively, for the continental and Indian Ocean sides of Bilu Island, and (4) the dominant process in the Salween River Delta was accretion, with an overall accretion area of about 10 km2, and an unstable accretion rate.