WAVE RUNUP ON A STEEP ROCKY BEACH WITH A SMALL RIVER PLUME
Orescanin, Mara S.
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To date, there are limited in situ data collected on the coast and at river deltas because the ocean–land convergence boundary is highly energetic and presents significant difficulties for experimentation. The focus of most river discharge research has been on large river deltas, and less attention has been paid toward small river plumes. Similarly, the surf zone on steep rocky beaches is also a less-studied topic because of logistical challenges. In the present study, we use remote sensing techniques to observe and collect wave runup at Carmel River State Beach, a steep beach with varying coastline features. The focus of this research was to investigate vertical-wave runup on a steep rocky beach with a small river plume. Elevation data collected showed Carmel River State Beach is very uniform in slope across the shore. Time-stack image analysis of wave runup at different sections of the beach showed that contrary to Battjes’ relationship between wave height and beach slope, near the Carmel River plume the greatest slope does not yield the highest vertical runup. Runup is affected by the hydrodynamics of river plume and coastal roughness by lowering the vertical height. The highest runup was observed on the sandy portion of beach, trailed by rocky shores, then river discharge. The empirical coefficients developed by Ahrens over smooth and rocky structured slopes produced runup values comparable to only those portions of the beach that had similar beach features.
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