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CoastSat.islands

Satellite-derived shorelines and 2D planform measurements for islands, extension of the CoastSat toolbox.

This toolkit enables users to measure shoreline position and two-dimensional planform characteristics (area and orientation) for small sandy islands.

Detailed methodology and application are described in: Cuttler MVW, Vos K, Branson P, Hansen JE, O'Leary M, Browne NK, Lowe RJ (2020) Interannual response of reef islands to climate-driven variations in water level and wave climate. Remote Sensing, 12(24), 4089

It has the following functionalities:

• Download and preprocess Landsat and Sentinel-2 satellites images from Google Earth Engine (as in CoastSat)
• Map the island contours as polygons (more accurate than the shoreline detection in CoastSat for small islands)
• Automatically generate a set of cross-shore transects around the islands

• Compute planform island metrics such as area, orientation and eccentricity

• Tidally-correct time-series of shoreline change along the transects as well as the entire island polygons

Installation

To run this toolkit you will need to have the coastsat environment installed (instructions in the main CoastSat toolbox).

Usage

The Jupyter Notebook in the repository shows an example of satellite-derived shorelines and island area estimation at Eva Island, Western Australia. There is also a Python script for users who prefer to use Spyder/PyCharm.

For the tidal correction, you will need time-series of water/tide levels at your site and an estimate of the beach-face slope. You can provide the tide levels in a .txt file as shown in the /example folder. Otherwise, you can use a global tide model to get the modeled tide levels. To use FES2014 global tide model to get the tide levels at the time of image acquisition, refer to the CoastSat.slope repository and follow the instructions provided to setup the tide model. If you don't have an estimate of the beach-face slope you can also obtain one using CoastSat.slope.

Issues

Having a problem? Post an issue in the Issues page (please do not email).

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