Numerical modeling of alongshore sediment transport and shoreline change along the Galveston coast

Abstract

An alongshore sediment transport and shoreline change analysis on Galveston Island in the period of 1990-2001 is conducted in this study using the Generalized Model for Simulating Shoreline Change (GENESIS). The study is divided into three main parts: 1. Assessment of the numerical accuracy of GENESIS, 2. Assessment of the alongshore sediment transport and shoreline change on the Galveston coast in the period of 1990-2001, and 3. Assessment of several erosion control practices on the Galveston coast for the period of 2001-2011. The first assessment shows that GENESIS has a numerical error which tends to be large for low energy wave (small breaking wave height) and large breaking wave angle. This numerical inaccuracy cannot be neglected and needs to be compensated for. This can be done, for instance, by adjusting the transport parameter K1. In the second assessment, good agreement between the calculated and measured transport/shoreline is achieved, particularly on the West Beach. Comparison between the potential alongshore sediment transport and sediment budget-inferred alongshore transport provides a systematic way of selecting the proper wave data set for the alongshore and shoreline change calculation. The third assessment proves that beach nourishment is the best alternative to overcome/reduce the erosion problem on the Galveston coast. Constructing coastal structure (groins, offshore breakwater) on the West Beach does not resolve the problem of erosion, but instead shifts it further west.