Geospatial techniques applied to the Texas regional sediment budget modeling study

Lewis, R. (2023) Geospatial techniques applied to the Texas regional sediment budget modeling study. In: ASBPA National Coastal Conference 2023, 10-13 October 2023, Rhode Island, US.

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HR Wallingford and Freese & Nichols have been working for the Texas General Land Office (TGLO) to develop sand transport models for the entire Texas coast in support of the Texas Coastal Resiliency Masterplan. The overarching aim of the project is to refine our understanding of sand transport pathways and develop sediment budgets for the gulf facing beaches of the Texas Coast. Sediment budgets for Regions 1 and 4 have been completed and the associated technical reports can be downloaded from the TGLO website. This presentation will provide an overview of the Regions 1 and 4 project, the datasets developed and how these are being made available to the wider coastal community to assist with the early planning stages of future coastal projects along the Texas Coast. One of the first tasks of the sediment budget project was to generate a long term timeseries of nearshore wave data along the coast. This resulted in nearshore wave climates at 67 locations along the coast spanning the period 1979 to 2019. These were used to calculate seasonal and interannual variability in longshore transport potential and to identify a representative year for the regional modeling. Nearshore bathymetry used in the regional model was based upon the recently updated ADCIRC model used by the USACE for the Coastal Texas Study and has been supplemented offshore with GEBCO data to the model boundary. After calibration of the wave and flow models, sediment grain size data from past projects and online databases were used to develop sediment characteristic maps for the sediment transport model which was run, fully coupled with the wave and flow model for the representative year. Bathymetric surveys and longer term dredge records were used as verification targets to confirm that the sediment transport model was predicting reliable shoaling quantities in the navigation channels. Net and gross sand transport fluxes were then calculated from model results in order to compute the resulting sediment budget as well as annual and monthly curves which show the cross-shore distribution of longshore transport at 67 transect locations along the coast. These transport curves will be very useful for planning any coastal work in these areas as the study found that the transport has a northwards or southwards direction depending on the time of the year, the position alongshore, and the position across-shore. The following datasets from the study will be made available on the GLO’s updated Texas Coastal Sediments Geodatabase (TxSed) geospatial viewer to support other coastal projects in the Region. Sediment budget shapefiles and corresponding annual sand transport fluxes; Littoral depth of closure points; Nearshore wave timeseries from 1979 to 2019; Bathymetry data • Sediment characteristic maps; Annual sand transport curves accompanied by the net, gross and cumulative transport at 10- yard intervals; Monthly sand transport curves accompanied by the net, gross and cumulative transport at 10- yard intervals.

Item Type: Conference or Workshop Item (Paper)
Subjects: Coasts > General
Divisions: Coastal
Depositing User: Helen Stevenson
Date Deposited: 13 Dec 2023 16:01
Last Modified: 13 Dec 2023 16:01

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