Coastal Processes and Causes of Shoreline Erosion and Accretion of the Baththalangunduwa Island in Sri Lanka

Abstract

Attached

Baththalangunduwa is an elongated sandy island. It is located in the Portugal Bay extending about 16 km long from north to south, and maximum width is about 680m east to west. Coastal processes mainly erosion, transportation and deposition of the Baththalangunduwa island has been calculated from the period from 1985 to 2017. After analyzing data spatially, erosion can be seen especially in the western flank of the island. The area is faced with waves, swells, storm winds and tides of the Palk Strait during the southwest monsoon period and vice versa accretion can be seen especially in the northern and eastern flanks and along the southern corner during the northeast monsoon period. The waves, wind pattern and tide of the Portugal Bay are responsible for the transportation and deposition in the area. Due to these processes, along the eastern and southern flanks of the island, there form micro landforms such as sandy lobes and hooks, mud flats, sea grass beds, mangrove patches, incomplete small bays and lagoon features. Most of these features are temporal, and limited to a week or a month or a season. According to the results, about 1 km erosion measured from the farthest point to the present coastal line, and total land extent change from 501 ha to 226 ha.