Abstract:

This data package is a comparison of observed marsh loss and modeled marsh loss from wind wave erosion in Barataria Bay, Louisiana from 1877 to 2015. The observed marsh datasets were generated by comparing an 1877 map with a Landsat image from 2015. The modeled marsh loss dataset was generated using a marsh evolution model that simulates marsh edge erosion by wind waves. The marsh erosion model is included within the data package along with the input and final map images (jpg) and data (mat, xlsx).

Suggested Citation:

Mariotti, Giulio. 2019. Measured and modeled marsh loss in Barataria Bay, Louisiana from 1877 to 2015. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-f3kb-ty90

Purpose:

To understand the rates and mechanisms of marsh edge loss by wind waves.

Data Parameters and Units:

Files (1) Measured_Erosion_Map.jpg and (2) Modeled_Erosion_Map.jpg: final map of (1) measured marsh loss and (2) modeled marsh loss in Barataria Bay from 1877 to 2015. Color code index for the map is 0=land both in 1877 and 2015, 1=open water both in 1877 and 2015, 2= land in 1877 and water in 2015. Files BS1877.jpg, BS1877.mat, and BS1877.xlsx: historical map data used in the generation of the Measured_Erosion_Map.jpg. Files BS2015.jpg, BS2015.mat, and BS2015.xlsx: Landsat image data used in the generation of the Measured_Erosion_Map.jpg. Files BS2015_modeled.jpg, BS2015_modeled.mat, and BS2015_modeled.xlsx: files generated by the model initialized with the measured 1877 map data (BS1877.mat) and then evolved up to 2015. The map created with these model results was then compared to the BS1877 map to create the Modeled_Erosion_Map.jpg. Cells have only 0 (marsh/land) and 1 (open water) values. The symbol NaN indicates a cell that is not part of the domain (the northern corners of the domain are blocked out, as well as the areas south of the barrier islands). Each cell is 30 x 30 m. The .mat file format should be opened using Matlab and can be used to directly run the model. Folder MarshEdgeErosionModel: contains the marsh erosion model. Model name=Marsh edge erosion model with wave symmetry. The model takes as input the file BS1877.mat and produces the BS2015_modeled output files used in the creation of the final modeled erosion map (Modeled_Erosion_Map.jpg). Time series input wind data: matrix of wind data from site (BURL1 NDBC data from 1991 to 2015), column 1: date (Matlab time), column 2: wind speed (tW in code, m/s), column 3: wind direction (tD in code, degrees). Model parameters amplitude: amount of asymmetry in erosion coefficient based on wind direction [adimensional], D: depth of the mudflat [m], aw: erodibility coefficient [m/day/(W/m)]. BS1877_30m: map of land and water in 1877, each cell is 30 m x 30 m. BS2015_30m: map of land and water in 2015, each cell is 30 m x 30 m. Functions calculatefetch.m: calculates fetch in domain geometrically mainwaveerosionstepe.m: calculates erosion at each cell. wavekfast.m: calculates wave number wavePOWER.m: calculates wave power. WindRose.m: makes wind rose figure. YeV.m: wind waves. The model is written in Matlab and can be run using either the Matlab or the Octave software. The model can be initialized with the .mat files to reproduce the simulations (Measured_Erosion_Map).

Methods:

The 1877 historical map was downloaded from https://nosimagery.noaa.gov/images/shoreline_surveys/survey_scans/T-1468-B.jpg (Title: Upper Part of Barataria Bay and Vicinity, Louisiana Survey: T-01468B State: Louisiana Survey End Date: 1877). The 2015 Landsat image was downloaded from https://www.usgs.gov/land-resources/nli/landsat/data-tools (Landsat 8, sensor: OLI_TIRS, Landsat scene ID = "LC80220402015006LGN00", file date = 2015-01-06T23:57:57Z, station id = "LGN", processing software version = "LPGS_2.4.0", wrs path, wrs row = 40, data type= L1T).

Individual Files: