Fig. 3: Quantitative basin-inlet evolution parameters through time.

a Tidal Prism (volume of water passing through the inlet throat in each semi-diurnal tidal cycle), b Cross-sectional Area of inlet throat below the tidally-filtered water surface elevation, c Volume of sediment sequestered in the ebb-tidal delta, calculated as the positive volume between the delta bathymetry surface and a surface created by projecting an “undisturbed” cross-shore profile some distance away from the inlet (see Dissanayake et al 2011). d Volume of tidal flats and channels through time. Volume of channels is computed as the volume of water between the evolving tidal basin bathymetric surface and the initial Mean Low Water datum at the inlet. Volume of tidal flats is computed as the volume of sediment within the basin lying between the initial Mean Low Water and Mean High Water datums (see Dissanayake et al., 2011), and (e) Mean water depth in basin at high tide and low tide for the control (no SLR), 5 mm/yr SLR, and 8 mm/yr SLR with 3 mm/yr accretion cases. Initially, all simulations have a much greater mean depth at low tide than high tide due to the deep channels and high elevation tidal flats. With continued SLR, without adequate sedimentation on tidal flats, mean depths at high tide increase with greater inundation over the marsh platform while mean depths at low tide decrease as expanding low tide inundation limits submerge lower elevation banks and tidal flats (e). SLR causes an increasing tidal prism (a), which produces an enlargement of the inlet cross-sectional area (b) and a growth in volume of the ebb-tidal delta (c). Likewise, there is a transfer of sediment from incising channels to accreting tidal flats (d). For the control case, tidal prism, channel volume, and tidal flat volume remain constant through time. Slight increases in inlet area and ebb-delta volume in the control case indicate that the initial basin configuration may not be fully in morphodynamic equilibrium with the forcing tidal conditions.