changescoastlines

Changescoastlines is the study of how coastlines change over time, focusing on the processes that move the land-sea boundary and the resulting effects on ecosystems, communities, and infrastructure. It encompasses natural drivers such as waves, tides, sediment transport, coastal subsidence or uplift, and long-term sea-level rise, as well as human influences including coastal engineering, sediment supply alteration by dams, and land reclamation. Coastal change occurs across scales from meters of retreat during a single storm to kilometer-scale shifts unfolding over decades.

Causes include erosion and deposition driven by waves and longshore drift, which reshuffle sediments; sea-level rise that increases coastal inundation and shoreline migration; and tectonic activity that can uplift or subside coastlines. Human actions modify these processes through the construction of seawalls, groins, and breakwaters, the removal or redistribution of sediment, and reductions in sediment supply due to damming or mining.

Measurement and data rely on historical maps, aerial photographs, LiDAR, and satellite imagery to track shoreline position over time. Rates of change are commonly expressed in meters per year of shoreline retreat or advance, with distances measured relative to fixed benchmarks. National agencies, universities, and research centers maintain coastal change datasets and develop models to project future shoreline behavior under different scenarios.

Impacts and management considerations include assessing erosion risks for communities, informing habitat conservation for beaches and wetlands, and guiding infrastructure planning. Adaptation options commonly referenced in policy discussions include beach nourishment, dune restoration, managed retreat, and the selective modification of coastal structures, all within integrated coastal zone management frameworks.