Assessing the influence of transect interval in monitoring and analysis of shoreline change

Abstract

Shoreline analysis helps to understand the coastal dynamism for decision-making in coastal management. As there are still doubts in transect-based analysis, this study attempts to understand the influence of transect intervals in shoreline analysis. Shorelines were delineated on high-resolution satellite images in Google Earth Pro for twelve beaches in Sri Lanka under different spatial and temporal scales. Shoreline change statistics were calculated using Digital Shoreline Analysis System in the ArcGIS 10.5.1 software under 50 transect interval scenarios, and influence of the transect interval for shoreline change statistics were interpreted using standard statistical methods. Transect interval error was calculated with respect to the 1m scenario as this has the best beach representation. Results revealed that there is no any significant difference (p > 0.05) of shoreline change statistics between 1 and 50m scenarios in each beach. Furthermore, it was found that the error was extremely low up to 10m scenario and then after it was subject to fluctuate in an unpredictable manner (R2 < 0.5). Overall, the study concludes that the influence of the transect interval is negligible and 10-m transect interval is ideal in shoreline analysis for the highest efficacy in small sandy beaches.