Tidal channel morphologic changes in recent decades. Conduit tidal channels outside of polder embankments (highlighted by yellow arrows) exhibit significant infilling across the region between 1972 and 2015. Many of these channels have simply become “dead-end” channels due to polder construction, while others have tidal restriction due to large sluice gates emplaced between polder islands. Many of these channels are reclaimed for rice agriculture or shrimp aquaculture, as shown in figures at right, and locally called ‘khas land’. A reorganization of tidal water transport can also be seen in the images on the bottom right with channel straightening and widening of remaining unrestricted channels. DOI: https://doi.org/10.1525/elementa.263.f2