• Mithila Madurawala
• Anusha Wijesundara
• Jagath Rajapaksha

This research provides comprehensive analysis of shoreline changes along the west coast of Sri Lanka, with a particular focus on the Colombo port city development. The primary objective of the study was to analyze shoreline changes using high resolution images obtained from Google Earth Pro. The DSAS 5.1 toolbox in ArcGIS was employed to 13 images during the period from 2005 to 2022 and the analysis done. Statistical calculations done with using analysis. The results unveiled a maximum erosion rate of 9.65 meters/year and a maximum accretion rate of 20.85 meters/year within the study area. Percentage of significant erosion in study area is 12.05 and percentage of significant accretion in study area is 29.55 based on linear regression rate calculation (LRR - rate of change of shoreline per year). Weighted Linear Regression (WLR - when fitting trend line, Weighted Linear Regression gives more importance to accurate data points) calculations also show similar results as linear regression rate calculation. In study area, average erosion is about 9.15 meter and the average accretion is about 42.55 meter according to Net Shoreline Movement (NSM - distance between the oldest and the youngest shorelines) calculation. However, the study found minimal shoreline impact within a 10-kilometer radius around the port city, as a result of series of breakwaters constructed and other development projects along the coastline of port city. The shoreline change is a complex interplay by natural processes and human activities emphasizing the economic significance of the Colombo coastal suburbs. The study emphasized erosion at the Kelani River mouth due to the development's impact. The port city expansion extended the shoreline by approximately 6-7 kilometers into the sea. However, overall, the port city project appeared to have a limited impact on the shoreline.

shoreline changes, coastal erosion, accretion, limited impact

"Impact on the shoreline due to the port city development off colombo on the west coast of sri lanka", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.12, Issue 12, page no.a734-a759, December-2025, Available :http://www.jetir.org/papers/JETIR2512097.pdf

"Impact on the shoreline due to the port city development off colombo on the west coast of sri lanka", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.12, Issue 12, page no. ppa734-a759, December-2025, Available at : http://www.jetir.org/papers/JETIR2512097.pdf