Abstract:
Coastal Zone of a country is a very important interface, through which land connects the
ocean. Monitoring the coastal zone of Sri Lanka is an important task in terms of
sustainable development and environmental protection. As a result of natural phenomena
and anthropogenic activities coastal zone is subjected to major changes. Therefore, it is
necessary to identify the temporal dynamics of shoreline around the country for effective
coastal zone management. Remote sensing and GIS methods can be efficiently used to
determine the temporal and spatial variations of the coastal zones quantitatively and
qualitatively. In this study, Google Earth satellite images have been used to analyse
shoreline changes in the Western and North-Western provincial coast during the last 15
years. To estimate the accuracy of results, the ground-truthing field survey was
conducted. The shorelines were delineated in Google Earth Pro 7.3 software. Tidal
variation and geometric errors were considered to calculate the uncertainty to eliminate
the errors in the analysis. Digital Shoreline Analysis System in ArcGIS was then used to
detect the shoreline change over the period by calculating End Point Rate, Net Shoreline
Movement and Shoreline Change Envelope means as the key statistics. The results show
that the average erosion rates as; -1.21±0.04 m yr-1
in Kaluthara, -0.54±0.63 m yr
-1
in
Colombo, and -0.7±0.58 m yr-1
in Gampaha districts. However, Puttalam district shows a
0.26±0.07 m yr-1
average accretion rate while the highest accretion rate 0.95±0.58 m yr-1
shows in the Wilpattu region. 75.6% of coasts in Kaluthara and around 65% of coasts in
Colombo & Gampaha have been subjected to erosion. Coasts of Puttalam have been
eroded by 28.1% and accreted by 71.9%. This study revealed that the Western province
coastal belt had subjected to coastal erosion than the North-Western province of Sri
Lanka. Thus, identification of the dynamic nature of shoreline helps to enhance coastal
zone management.
Keywords: Shoreline, Remote sensing, Dynamic, Erosion, Coastal changes
