Field Measurement and Modeling of Sediment Transport along a Sandy Pocket Beach, Central West Coast of India.

Sandy beaches generally are influenced by various coastal dynamic processes and undergo constant changes. The present study is an attempt to understand the hydromorphodynamic characteristics of a sandy pocket beach situated along the central west coast of India through field observation and numerical modeling. Multiple oceanographic instruments are deployed to capture the actual nearshore hydrodynamics, and sediment transport is measured using the streamer trap method suggested earlier during the premonsoon season. The observed vertical distribution of sediment fluxes showed a typical upward decrease from the seabed to the water surface. It is also noted that nearly 75% of the trap measurements showed that near-bed transport is higher than the depth-integrated values, confirming that the maximum sand remobilization is in the vicinity of the seabed rather than in suspension. The beach profiles of selected transects were measured during the pre- and postmonsoon seasons to understand the bed evolution. A one-dimensional numerical model, developed using XBeach and validated with field-observed values, demonstratively captured the effect of monsoon hydrodynamics on the beach profiles with fair accuracy. The various significant numerical parameters that govern the morphodynamics in the sandy beach are evaluated through a comprehensive analysis. In the end, the simulated beach profile that captures the effect of monsoon and storm are in good agreement with that obtained from field observations, with Brier Skill Scores (BSSs) of 0.69, 0.76, and 0.74 for Profiles 1, 2, and 3, respectively. [ABSTRACT FROM AUTHOR]