Transect based analysis versus area based analysis to quantify shoreline displacement: spatial resolution issues.

Area of Science:

• Coastal geomorphology
• Geographic Information Systems (GIS)
• Remote Sensing

Background:

• Shoreline position analysis is crucial for coastal management.
• Area Based Analysis (ABA) and Transect Based Analysis (TBA) are common methods.
• Understanding method performance across different coastlines is vital.

Purpose of the Study:

• To compare the Area Based Analysis (ABA) and Transect Based Analysis (TBA) methods for shoreline change detection.
• To evaluate the influence of varying analysis scales (sector length) on method correlation.
• To assess method performance on both linear and irregular coastlines.

Main Methods:

• Utilized GIS tools to compare ABA and TBA on two Italian coastlines (Punta Ala and Follonica).
• Employed differential global positioning system (DGPS) for high-accuracy shoreline data acquisition.
• Analyzed shoreline displacements across multiple sector lengths (50m to 800m).

Main Results:

• ABA and TBA show high correlation for sector lengths up to 100m on both linear and irregular coasts.
• On smooth shorelines, correlation remains high even with longer transects.
• Correlation significantly decreases for longer transects on irregular shorelines.

Conclusions:

• The choice of analysis method and scale is critical, especially for complex coastlines.
• ABA and TBA are comparable for short-scale analyses but diverge with increasing scale on irregular shores.
• GIS-based shoreline change analysis requires careful consideration of method and scale for accurate results.