Coral Degradation Analysis of the Great Barrier Reef
Results
The 2004 Hyperion data was used as the initial state and 2015 data was used as the final state. The comparison matrix to the right, records changes of each class in pixel counts, percentages, and area (square meters).
The change detection figure is the result of our area of study from 2004 to 2015. Red color indicates there is no more coral there while gray color indicates there is new live coral while the white color is unclassified.
Calculated by the percentages of unchanged pixels, about 54% of the data remained in the same classification between 2004 and 2015 while 46% have switched. For Live Coral, about 58% of it has changed into No Coral class between 2004 and 2015, indicating that a large amount of coral reef has died off during this period. Change detection statistics show that only about 15% of the Live Coral from 2004 is still remaining in 2015, thus correlating this with evidence of the current sea level temperatures rising trend, we can conclude that the effect of warm ocean currents, the El Nino phenomenon, has caused the corals to bleach and die, resulting in the gradual disappearance of coral reefs over time.
Change Detection of the Great Barrier Reef (2004-2015)
Discussion
The purpose of this experiment was to verify that El Niño's effect have a measurable impact on the size and health of coral reefs. After carefully analyzing our results, we found that there is a significant difference in the amount of bleached coral in our area from 2004 and 2015. By simply inspecting our classified images, we were able to tell that there was more bleaching in 2015, even before change detection was performed. The change detection went on to verify our hypothesis. Because there was little change in the amount of bleached coral from 2004-2006, we conclude that most of the damage to the coral reef happened this year.