Reservoir Model for Calculating Natural Sand Bypassing and Change in Volume of Ebb-Tidal Shoals, Part I: Description

provides information on a mathematical model developed to calculate natural sand bypassing and change in volume of ebb-tidal shoals. Subsequent CHETN’s in this series will describe the interface and generalizations of the model to cover flood-tidal shoals, inlet-entrance channel, and other morphologic features at inlets. BACKGROUND: An inlet is an opening through a landmass that hydraulically connects a large body of water such as an ocean or sea to a smaller body of water such as a bay or lagoon. The ebb and flood currents generated by the tide (or by seiching in the case of large lakes and inland seas) redistribute sediment transported toward the inlet channel by the wave-generated longshore current. The dynamic balance of the various sediment-transporting mechanisms creates morphologic features such as shown for in Figure 1 for Shinnecock Inlet, on Long Island, NY. The picture was taken on a calm day, and the various sand bodies around the inlet can be seen through the water. Interpreted sediment-transport pathways among the sand bodies or morphologic features are drawn in Figure 2. On this coast, longshore transport is directed strongly to the west (to the left in Figure 2). Sediment (predominantly sand) moving to the west reaches the updrift attachment bar (labele