Coastal wetlands provide a livelihood for local communities and
simultaneously provide services that include coastal protection,
enhanced carbon storage and habitats provision for both terrestrial- and
marine life. Yet, the development of climate resilient management
strategies that need to account for changes that might occur in the
coming decades is challenging due to the variable response of coastal
ecosystems. This is because coastal ecosystems, including mangroves,
wetlands and tidal flats, are directly linked to coastline dynamics, as
coastlines can move seaward, when waves are low and sediment
availability is high, or retreat when the opposite is true. Particularly
the long-term fate of the mud dominated coastline of Suriname, part of
the Guianas coastal system stretching from the Amazon to the Orinoco
delta, is determined by migrating subtidal mudbanks that cause a cyclic
instability of alternating erosion and progradation phases. We present a
semi-automatic remote sensing approach to quantify the influence of
mudbank migration on coastline dynamics along the entire coast of
Suriname. We validated our approach with high resolution drone imagery
collected at contrasting locations, indicating average accuracy of
changes in coastline position to be within 50 meters. This suggest we
can apply our methodology on all available Landsat images between 1985
and 2020, acquired over the heterogonous and complex coastal landscapes.
The results show that regional forcing mechanisms, related to migration
of six to eight subtidal mudbanks in front of the Suriname coast, have a
strong imprint on local coastline dynamics with an average 25
m/yr-1 expansion during mudbank presence, and 8
m/yr-1 retreat of the coastline during mudbank absence
between 1986 and 2020. More importantly, we found that not all spatial
and temporal variations in the magnitude and timing of local changes can
be explained by migrating mudbanks. This demonstrates the importance of
incorporating changes that cannot be explained by regional forcing
mechanisms in management frameworks that aim at explaining current
variability and predicting future coastline changes.