“…Macroscale geomorphological units of tidal flats indicate morphological patterns controlling the entire flat system, such as profile geometry, e.g., convex and concave profile morphology (Gao, 2009;Zhou et al, 2016), and zonation of flat sediments (Roberts et al, 2000;Zhang et al, 2018). Mesoscale geomorphological units refer to those features with the length of 1-10 m, including scarps occurring at the boundaries between flat and vegetation (salt marsh plants and mangroves), ridges (Weill et al, 2010;Weill et al, 2012), sand waves (Allen, 1980;Besio et al, 2006), and waterways (Weimer et al, 1982;Pieterse et al, 2016), as well as tidal creeks (Blanton et al, 2002). Microscale geomorphological units, which generally less than 1 m, include flat surface cracks (Gardel et al, 2009), sand grains (Harms, 1969), linear scour pits (Sumer et al, 2001), biological holes (Takeuchi and Tamaki, 2014), and flat surface uplift caused by fish or large burrowing, which usually located in the low tidal zone (Dott and Bourgeois, 1982).…”