A walk in wetlands morphology and inundation patterns

Balanced conservation strategies are needed to ensure the protection of wetlands in the twenty-first century. To guarantee the success of wetland restoration projects, it is essential to better understand the characteristics of these fragile sites and the driving mechanisms of change. This study characterised the morphology of wetland platforms at five backbarrier sites distributed around the world and subject to various tidal regimes (micro- to macrotidal). Wetland ecogeomorphologic units were manually mapped and classified into upper-, mid-low marsh, tidal flat and channel, using high-resolution Digital Elevation Models (DEMs). Differences in elevation, slope and hydroperiod metrics between morphological units and study sites were assessed, as well as the influence of tidal range and associated inundation patterns on wetland zonation. Upper and mid-low marshes showed steeper intra-slopes compared to channels and tidal flats, with the latter exhibiting longer hydroperiods. No significant differences in normalised elevation and hydroperiod were detected between study sites. Steeper slopes were observed in microtidal systems compared to meso- and macrotidal systems, likely due to constrained horizontal migration. These findings enhance the understanding of the regional patterns of wetland morphological succession, and highlight that tidal range is not the primary driver of spatial variability in wetland zonation. Moreover, this baseline dataset of morphological thresholds can be used to support future large-scale comparisons and inform sustainable management strategies for coastal wetlands, particularly in the context of climate change. Future studies should analyse additional landscape metrics (e.g., vegetation density, sediment accretion rates) and evaluate the cumulative effects of site-specific drivers on wetland geometry. •Meso- and macrotidal wetlands exhibited greater vertical morphological differentiation and more extensive tidal flats than microtidal systems.•Slope variability might be a useful indicator for distinguishing wetland zonation under different tidal regimes.•The vertical succession of wetland morphologies is not solely controlled by tidal range.