How to determine coastal erosion in matlab?

Cícero Vicente - 2023-07-01T10:40:51+00:00

Question: How to determine coastal erosion in matlab?

    I have a question that I don't know how to solve or what direction I should take. I have a chronological analysis of 73 coastlines (.shp) at Itapoá beach (Santa Catarina, Brazil), and I would like to determine which of these lines are in a state of erosion, but I don't know which variable to use as a basis. I have as data that make up the "coast" matrix: "BoundingBox", "X", "Y", "date", "mean", "stdDev", "system0x3At".   Ps:   "X" and "Y": are double data that represent the points collected in lat and long along the coast that form the coastline. Could you guys help me?    

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Expert Answer

Kshitij Singh answered . 2025-11-20

To determine coastal erosion using MATLAB with your dataset, you can analyze changes in the coastline over time by comparing successive shoreline positions. Here are the steps to guide your analysis:

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Steps to Analyze Coastal Erosion

1. Understand the Dataset:

• "X" and "Y": Represent the geographical coordinates (latitude and longitude) of the coastline.
• "date": Represents the time associated with each coastline.
• Other variables: Could provide additional context but might not be directly related to erosion.

2. Define Erosion:

• Coastal erosion is typically determined by a landward shift in the coastline over time.
• Define reference points or cross-shore transects perpendicular to the baseline to quantify these shifts.

3. Load and Visualize the Data:

Use MATLAB's Mapping Toolbox to load and visualize the shapefile data.

 

% Load the shapefile
coastlines = shaperead('path_to_your_shapefile.shp');

% Plot all coastlines
figure;
hold on;
for i = 1:length(coastlines)
    plot(coastlines(i).X, coastlines(i).Y, 'DisplayName', datestr(coastlines(i).date));
end
legend('show');
xlabel('Longitude');
ylabel('Latitude');
title('Coastline Chronology');
grid on;
hold off;
 

6. Determine Erosion/Accretion:

• Negative distances indicate erosion (landward movement).
• Positive distances indicate accretion (seaward movement).

7. Statistical Analysis:

• Compute mean erosion/accretion per transect or coastline.
• Identify regions of significant erosion

 

meanErosion = mean(erosionDistances, 2); % Mean per transect
significantErosion = find(meanErosion < -threshold); % Define threshold

8. Generate Report or Visualization:

• Highlight eroding transects on the map.
• Create time-series plots of shoreline position for specific transects.

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Key Considerations:

• Coordinate Transformation:

  • If "X" and "Y" are in latitude/longitude, you may need to convert them to a Cartesian coordinate system (e.g., UTM) using projfwd or deg2utm for accurate distance calculations.

• Temporal Resolution:

  • Ensure the "date" variable is properly formatted and use it to analyze changes over consistent time intervals.

• Erosion Thresholds:

  • Define thresholds for significant erosion based on the scale of your analysis.

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Tools and Functions:

• Mapping Toolbox: For handling and visualizing shapefiles.
• shaperead, plot, interp1: To read and interpolate data.
• Custom Scripts: For transect generation and distance calculation.

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This approach provides a framework to quantify and visualize coastal erosion. Let me know if you'd like assistance with specific steps!

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