METHODS
ALGORITHM
1. Identify Wet and Dry Seasons
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2. Download the oldest cloud-free Landsat Level 2 (or 1) Surface Reflectance
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3. Compare the oldest images to more recent images for both wet and dry seasons
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4. Create 4 NDVIs (summarize NDVI values)
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5. Use change detection to test the hypothesis that there has been a significant decline in NDVI or greenness between the two time periods and seasons
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6. Ground truth results and conclude if our data supports/confirms our references and outside research
LANDSAT IMAGERY
Finding images was made difficult by extensive cloud cover that obstructed much of the Big Island. In addition to this, we were unable to use any Landsat 7 imagery that might fit our ROI because of damage to the sensor which causes line tracking to be present in the imagery
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Both of the early images, from 1977 and 1978, are Landsat 2 imagery in which we used Bands 5 (red) and 6 (NIR). For the recent images, both from 2020, we used Landsat 8 imagery, specifically Bands 4 (red) and 5 (NIR).
IMAGERY DATES
DRY SEASON
WET SEASON
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January 7, 1978
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January 3, 2020​
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October 27, 1977
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October 17, 2020
ENVI TOOLS
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Created a shapefile for our ROI
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NDVI
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Change Detection
RESULTS
Created six maps by transferring final images into ArcMap and symbolizing using a divergent color ramp to best show the change in greenness or health of vegetation.
LANDSAT 2 AND LANDSAT 8 IMAGERY
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October 27, 1977
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October 17, 2020
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January 7, 1978​
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​January 3, 2020​
