Shoreline Development During a Four-Decade Period, Along Al Qunfudhah Coast, Saudi Arabia

The coastline is a constantly evolving boundary between land and sea, shaped by natural forces and human activities. Given its significant ecological and economic value, this zone faces increasing pressures, highlighting the need for continuous monitoring and improved understanding to support sustainable management. This study analyses the spatial and temporal changes along the Al Qunfudhah coastline from 1984 to 2020. Using a combination of multi-temporal Landsat satellite images and geographic information system tools—specifically the digital shoreline analysis system—the research tracks changes over time. Shoreline positions were accurately extracted using automated methods, particularly the Canny edge detection algorithm. Over the 36-year period, analysis using the linear regression rate (LRR) and end point rate (EPR) methods revealed a general pattern of slight shoreline advancement. The highest rates of accretion were recorded at 12.43 m/year (LRR) and 13.36 m/year (EPR), with average rates of 3.63 m/year and 4.17 m/year, especially in the northern region where a corniche road was developed along the coast. Conversely, the most significant erosion occurred near the boat port, with maximum rates reaching −24.4 m/year (LRR) and −20.9 m/year (EPR) and average rates of −1.23 m/year and −1.08 m/year. These results offer valuable insights into the factors driving coastal changes and provide a scientific foundation for making informed, sustainable decisions about the future of the Al Qunfudhah coastline.