The Tidal Headland Test Case: ROMS & Delft3D

Richard P. Signell, John C. Warner, Christopher R. Sherwood
U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole

The development of sand banks driven by tidal flows around a headland is an excellent test case for coastal sediment transport models http://woodshole.er.usgs.gov/project-pages/sediment-transport/Test_Case_4.htm. It is simple to configure, but tests many complex related processes. Flow asymmetries induced by the headland in the oscillatory tide lead to net erosion and deposition over the tidal cycle. As sand banks formed on either side of the headland grow, they start to affect the flow dynamics. The equilibrium state is determined by the strength of the tidal flow, the depth of the water, the length scale of the headland, the sediment grain diameter, and the wave field. Running this test case to equilibrium requires morphological feedback, wetting and drying, wave-driven transport and thus is a good test for the new shallow and nearshore processes in ROMS. The ROMS results are compared and contrasted to Delft3D results, which has incorporated these processes for several years.