The fate of tidal flats across the world

Abstract

Forty percent of the human population lives within 100 km of the coast, and relies on it for their livelihood. One of the most prevalent coastal ecosystems in the world are tidal flats, which provide essential ecosystem services such as storm protection. However, tidal flat extent is on the decline, with 16% of all tidal flats already lost between 1984 and 2016. The underlying mechanisms leading to this decline are poorly understood. Studies have suggested suspended particulate matter (SPM) to be of influence in the changing morphology of tidal flats. To be able to remote sense SPM globally, turbidity is often used as a proxy. In this study, the relationship between turbidity change and a change in tidal flat morphology on a global scale between 1984 and 2013 is researched via remote sensing. The change in morphology of a tidal flat is define as a combination of both saltmarsh area change and elevation change. In 84.4% of the researched tidal flats, a negative correlation was found between turbidity and saltmarsh extent. However, no strong correlation between turbidity change and elevation change was found. Overall, this study found that a change in turbidity can explain part of the morphology change in tidal flats over time. Improvements to the method could result in more precise data on the correlation between turbidity change and elevation change and therefore help better understand the relationship between turbidity change and morphology change in tidal flats all over the world.